2018 ~ The Year of SSB Transceivers

Clean Off the Work Bench ~ New 2018 Transceiver Projects!

1/18/2018 ~ Now you found it -- How to Fix It?

I was so excited yesterday that I found the source of the problem --it was not the rig per se or a test of my schematic reading or soldering skills --it was RF in my back yard!

One comment on the you tube video --how do you fix it as this will also have implications on the IC Transceiver build. My XYL suggested moving to an upscale neighborhood that has antenna restrictions. Should note for over 50 years she has absolutely hated the hobby so her response is quite clear -- make me QRT.

 

In the Page 104, SSDRA design had as a front end a simple coil and a cap for  20 Meters. Whereas the 80 Meter filter uses a Cohn type tuned network. So one possible fix for me since I don't operate CW or Digital modes is to come up with a Band Pass Filter in place of the simple tuned circuit that would be centered on the phone band and with care could offer a 15 to 20 dB reduction to signals below 14.150 MHz. That is possible.

 

Another would be to design a trap "notch filter" centered on 14.075 MHz which of course if I did operate digital would kind of makes things hard for any digital operations; but not incompatible with my operating mode desires.

 

This is a first for me but it does appear to be limited to 20 Meters.

 

73's

Pete N6QW

1/17/2018 ~ Trouble Shooting Mystery Solved

So Ok, yesterday I determined that some evil external force was de-sensing the front end of my new (rebuilt) transceiver. But the wild goose chase was invaluable as I had a real chance to dig into what I had done some 35 years ago where the documentation of what had been done got lost in one of the 10 moves I made in that 35 years. I even rebuilt the active mixer --so all is not lost. My detailed recent journey did affirm I knew what end of the soldering iron was hot --even 35 years ago. BTW I did have to go before the FCC Examiner to get my Extra --no box tops here!

 

This morning I had an inspiration and that was to connect my Rigol scope to the rig's antenna with the rig turned off and just see what I could see. Initially there was a bit of background noise and then the screen filled with signal. I had the counter function engaged and quickly noted that the frequency of the strong signal was 14.07475 MHz and it was really strong. I observed several cycles to affirm and verify what I first initially thought this morning. Boom someone close by is operating in the digital mode --and I mean close by like maybe 800 feet. It was a ham on the next block and just recently I noted he sprouted a new antenna on his roof.

 

Next I turned on the rig and tuned down to 14.07475 and still with the scope connected across the antenna spotted the screen filling up and at the same time the rig's S Meter showed about a 30 DB /S9 signal. I watched that for several cycles and indeed that was the culprit. Keep in mind that was 30 DB/S9 in a de-sense mode. My ham friend must have gotten a new radio toy for Christmas as I have never had this problem before.

 

For your amusement and amazement I made a video of this morning's solving of the mystery. See below. There was a method to my sharing this adventure. In troubleshooting a rig, often you have the data right in front of you -- the problem is one of how to connect the dots. It took me two days but was an invaluable learning experience for me -- there was nothing wrong with the rig! The problem was the rig was being subjected to very strong signals in close proximity -- connected to a beam only made the signal stronger!

 

 There we have it -- another ham is the problem. Feel a lot better now.

73's
Pete N6QW

1/16/2018  Tribal Knowledge Trouble Shooting (1/17 Update)

As we prepare to build the IC Transceiver I wanted to spend some time on a real world rig
problem that directly applies to the IC Transceiver project. What to do when something is not right? In the most recent transceiver project (in 2018) I rebuilt something that I had originally built in about 1985.

 

The 2018 Reborn 1980's rig. The LED next to the Meter Glows Green on Transmit. How Cool?

There is a story behind this rig and it all started with the Solid State Design for the Radio Amateur (SSDRA). You have often heard me say that I prefer this publication over EMRFD. Rebuilding this project affirmed that position. If you go to Chapter 5 page 104, you will see a two band Superhet (20/80 Meters) which uses a 9 MHz IF. When I looked at that schematic, back some 35 years ago my first thoughts were why can't this be made into a transceiver --which it was.

(For those who do own a SSDRA there is a close parallel to the page 104 design and the K1BQT 75M Transceiver in that both use an active mixer, both use the MC1350 and both use the same AGC circuit. Don't overlook the diode steering in K1BQT's rig to steer the signals into/out of the filter. Undoubtedly there has to be parallel influences at work here! So spending some time with SSDRA is most useful before building the IC Transceiver. Like I said my copy of EMRFD is a great bookend!)

The Front End active Mixer is a 40673. Having some 3N211's I used that for the active mixer. The plan was to use diode steering so that the Rx signal would be diode steered into the IF stage. The other half of the steering would be the output of a diode ring balanced modulator with a 741 Op Amp microphone amplifier.

Thus signals passing through the IF would either be the Received signals or the low level Transmit signals. Based on a concern I had at that time with using the KVG 5 Pole filter I added a simple 2N3904 buffer stage ahead and following the filter. The idea was both in SSDRA and the seminal ON5FE 1970's IF Module. From there just as on page 104 the signals were routed to the MC1350 IF amp and thence on to the singly balanced diode ring. Noteworthy I kept the AGC circuit with thoughts of using it with ALC like in the IC Transceiver. [That may not actually be a good idea --will explain in a later post --but the ALC control level is affected by the level set for the AGC.]

So now looking at the singly balanced mixer (the OBTE are left to figure that out) I added more diode steering to the what is normally the LO Port. Thus I had diode steering of the BFO on receive and more diode steering of the output of the single balanced mixer to the audio amp.

But on transmit the LO port was now fed the LO signal from the VFO and the output now steered to a band pass filter and then on to a 2N5179 RF stage. [Hayward loved 2N5179's]. From the 2N5179 the RF signal was passed to a driver stage and then on to an IRF510.

So the changes I made in the upgrade are I ditched the diode balanced modulator and removed the carrier oscillator circuitry. In its place I installed an ADE-1 and the BFO signal is now supplied by a CLK2 from the Si5351. The LO signal (above the incoming at 23 MHz) is supplied by CLK0 of the Si5351. I was unhappy with having a single balanced mixer on today's bands so I removed all of that circuitry and installed a TUF-1. [As an experiment with some surplus DBM's there is now a TFM-2P installed there which is a TUF-1 on Steroids.] The RF Driver is a 2N2222 driving a BD139 and the final a IRF510. Needless to say NO Analog VFO's or Crystal BFO as these technologies are out of step with the rigs of today!

Active Mixer now a 3N209

TFM-2P DBM, MC1350 to the right of the DBM

BPF and 2N5179

2N2222 and BD139 Driver Stage

IRF510 Final Amp bolted to the back wall of the case. Having a CNC sure is nice!

 

 

So all was going nicely with the new rig when suddenly I would encounter an intermittent condition on receive where the signal level (more like volume) would be reduced. The Transmit signal appeared to be not affected. So it was a receive problem.

My first "noodling effort" was to focus on the active mixer stage. Why? --well everything after the mixer is more or less common to transmit and receive. The only item not so other than the receive mixer would be the audio amplifier chain.  But I concluded, that the only  possibility since it worked well on transmit, was the active mixer.

 

The trimmer caps originally installed were orange in color and had a range of 15 to 60PF which I found in other installations had a finite life of so many rotations. I thought perhaps they were failing and would change value thus "untuning" the tuned circuits. So I decided to replace all of the components in this stage. I replaced the 3N211's with a 3N209 which was actually sent to me by the man himself, W7ZOI. With everything replaced I fired up the rig and all worked. The only thing this proved is that 1) I did not make any wiring errors and that 2) I do know how to read a schematic.

 

My euphoria was short lived for the problem returned. Again transmit was not affected only receive. I guess I should have read the tea leaves more closely as when the condition occurs the signal drops but does not go away.  It just loses signal strength. I prodded and poked components all along the receive path yet the condition did not abate.

 

A little more about what I am seeing (hearing). It is a cyclic thing where the signal weakens for a short duration and then gain comes back full on. Hmmm could there be a bad component in the AGC circuit that was cycling the MC1350 so that gain was being reduced intermittently. I was mystified. Again transmit was not affected. Disconnecting the AGC had no affect on resolving the cyclic de-sense.

 

So some other things I tried -- looking at the whole system. What about an antenna issue where maybe there was an issue with coax/beam (20 Meters)? So then I switched antennas to the dipole which is actually 3/2 wavelengths on 20 Meters. Boom same problem so that led me (falsely) back to the rig. Should have thought a bit more about that conclusion --if it loaded OK on transmit with no issues then it was not the antenna. I was bummed out as I just could not see what was the problem.

 

Well I decided the best course was to lay aside the rig for a bit and give this more thought. I heard a few stations on and so I put a different 20 Meter rig on the air -- Boom and double Boom --Same problem! Wait a minute. Tried a third 20 Meter radio -- same problem and so it was with a 4th 20 Meter Rig. Additionally one rig is a 20/40 Meter version -- there did not seem to be a problem on 40M. Thus the de-sense signal is not totally broad band. Thoughts floated back to when as a kid I built a TV killer which blanked out one of the TV channels so I didn't have to watch the Ed Sullivan show but avoided impacting the other channel which was the Colgate Comedy hour. Hmm was some one in the neighborhood trying to stop me from operating on 20 Meters????

 

So now the pieces were beginning to fall into place. There is something new in the neighborhood that is cycling on off and is a very strong signal that is causing my rigs to "de-sense".

 

So while replacing the active mixer may have not been necessary it does make me think it was not all bad. Tomorrow I will do more snooping around the neighborhood, On my morning walk I will bring along the rig with a battery pack and a short antenna to see if I can pinpoint the culprit.

 

All of our utilities are underground and it was not my neighbor welding in his garage as I know when he is doing that. Several years ago we had the "pot lady" growing weed in her garage and it was the cycling of the grow lights that made RF noise. We didn't get any new appliances so it is not in my QTH. It has to be a pretty strong field to cause a de-sense of the front end. I am having a hard time internalizing that the signal would be so strong as to essentially overload the rigs. Hearing RF interference (pot grow lights) is an order of magnitude different from overload.

 

I want to also re-verify that all the rigs are affected and that I have not missed anything. Oh I have three power supplies -- the same problem with any of the supplies. So I eliminated the power supplies as the root cause. Time now to rest and reflect.

 

This is a classic "Easter Egg Hunt" looking where all the eggs are hidden. I have never seen anything like this before.

 

Will keep you posted. But this could be a problem that might have been encountered with the IC Transceiver and I would have been chasing a bad circuit/component/wiring error when it was something entirely different. Sometimes the obvious is not so obvious --why did I immediately think there was a problem with the rig? Good question to always ask first!!

 

73's

Pete N6QW

1/13/2018 ~ More Considerations: To QRP or Not QRP That is the Question?

For those who may not know this I am a member of the QRPARCI Hall of Fame. I believe my selection was quite accidental and most likely those who are board members and regular members probably are wondering why as well. I am not a closet QRO guy hiding out as a dye in the wool QRPO guy; but freely admit my penchant for something more than 5 Watts!

 

There are many choices in our hobby so don't get snooty about having a DXCC certificate having done so running no more than 5 watts. All I can say is congratulations; but also be a ham and recognize others may not share your interest.

 

My interest in QRP is not driven by a desire to put a rig in a back pack, don foul weather gear and climb to a local mountain so I can operate in a driving snow storm and claim that I worked a station 200 miles away on 200 milli-watts SSB all the while braving off the elements.

 

Let me tell you why so many of my rigs end up being QRP. Early on I tried to build rigs that put out 50 watts from just the rig itself. For the most part I was terribly unsuccessful! Some how everything worked FB, until I got to the final amp stages where regularly there seemed to be problems with RF Feedback, bias issues and the heat problem creeping over to other parts of the rig. Was I being punished for running more than 5 watts?

 

What I did find is that almost 100% of the time everything worked great up to the 2 to 5 watt level coming out of the driver stages. Thus a solution -- build rigs that reliably put out 2 to 5 watts with no hiccups or burps and then add an outboard amp. So QRP level rigs for me was not to be a QRP enthusiast; but rather as a solution to some technical problems. I frequently run 600 watts with my homebrew rigs with no problems. On rare occasions I run my rigs straight through to an antenna running just 5 watts just to say I can run QRP but that is not my usual approach.

 

Now to the IC-Transceiver. While I intend to follow my usual practice of having an output in the 2 to 5 Watt range just to say it works flawlessly, there are some amps that look like they can be built in the rig itself without problems. One of those is a 20 Watt amplifier from K5BCQ which can be found at this link (scroll down as there are a lot of other projects on the page). Keyes and John know their potatoes so it is an amp that is "bullet proof".

 

http://www.qsl.net/k5bcq/Kits/Kits.html

 

So this is another piece to IC Transceiver. At the 20 Watt level you will get an order of magnitude (that is 10X for the OBTE) of greater contacts versus 5 Watts and thus a worth while approach. The 20 watts will also drive many of the MOSFET Solid State Amps to the Kilowatt level. But that is a project for another time.

Stay Tuned.

73's
Pete N6QW

1/12/2018 ~ Design Considerations & Decisions

For the most part we will be building the basic K1BQT transceiver or I should say a major part of the design --very likely 51% but not all of it. Today's post will cover the original design and what we will be changing and how we will change it. Firstly the original article was for a single band (75M) and employed a rather exotic way of getting 30 watts (a 28 VDC RF MOSFET) to the antenna. Some 33 years later we have at out disposal many tools and techniques that weren't even on the drawing boards in 1985. We hope to do this in an ordered fashion:

 

1. The original design used an analog VFO and crystal BFO. The obvious 2018 change would be a Si5351 which will handle both functions and costs $8 as a complete board. The control of the Si5351 will be an Arduino Nano and the display a color TFT. With a bit of shopping this can be had for a $20 bill. The Arduino using built in capability enables ready band changing and control of other functions --so a bonus. More on this to come.
2. The transmit mixer stage which is a MC1496 has a broad band output which is fed into a gain controlled 40673 Dual Gate MOSFET (DGM) . If you look at the schematic you will see a trim pot connected to Gate #2 which is labeled "Drive". That is a nice feature --we will keep it, But we will first start by ditching the 40673 (unless you have one in a bin) and replace it with two J310's connected as a DGM which are much more readily available and can be had for 20 cents a piece. The output side of the 40673 in K1BQT's design is connected to a band pass filter (yes OBTE that is a BPF) and in turn that drives the IRFD1Z3 which has a low pass filter on its output -- the classic 3 pole. Today you would probably want something a lot stiffer than 3 poles! The IRFD1Z3 is literally "unobtanium" but it looks like the BS170 would work and I will runs some tests to affirm that choice.
3. So N6QW's Plan would be to follow the DGM stage with a switchable Band Pass Filter and using the W3NQN's stock filter design follow the BS170 stage with these filters, again switchable.  Rick, K1BQT, was careful to note that if you placed his design on other bands --you needed more filtering. To recap we will be changing the driver stage to include J310's with a BS170 amp stage and more/better and switchable filters. There is some solid sense to have a LPF follow the BZ170. In the original design the IRFD1Z3 could produce 300 MW of output thus you could make this a Qrppp rig and bypass the final stage or pick off the output and run that into a transverter for use on VHF or UHF SSB. Lots of possibilities but definitely more filtering needed.
4. While we are on filters, when I built the LM373 transceiver which can be seen at http://www.n6qw.com  I was faced with a situation, because of this being a single IC transceiver of how to add Band Pass Filtering without using a lot of exotic switching. The answer was two Band Pass Filters with one in the receive side and the other on the transmit side. So while it adds a bit to the project in terms of cost and hardware, I am proposing two sets of band pass filters. The original design did this! You will note the BPF ahead of the MC1496 receive mixer and we just discussed the one following the 40673. The only difference we will be having switchable filters depending on the band.
5. The original design used a 28 VDC RF device the MRF138. That is one expensive device and was a bit of a problem in that portable operation would be difficult but not impossible. One approach would be like the Sideband Engineers SBE-33 vintage 1963 --it was an AC only unit and to use it mobile they had a DC to AC inverter. Small 150 Watt DC to AC Inverters can actually be had for a $20 bill -- but that is not so easily done if you want to take it trail camping. Technology offers us netter solutions today. One solution is to use an IRF510 and limit yourself to 5 Watts. Lots of QSO's can be had with 5 watts. Other RF MOSFET's from Mitsubishi (RD series) can put out a lot more juice at 13 volts DC -- like 20 watts. There are kits being sold that offer all that you need [Check the K5BCQ website for available kits.] Communications Concepts Inc. sells a Bipolar kit that will produce 20 Watts with 100 MW of drive --another option for you.
6. Now comes the "how to switch the filters" part. We have previously identified three locations where switching is needed actually there are 5 places. 1) the LO, 2) Rx BPF's, 3) Tx BPF, 4) Driver Tx LPF and 5) Final Amp LPF. So how do you do this? We have many options and I will take a few minutes to look at a subset of the switching. Boiled down we have basically two options for the switching and those include diode steering and relays. Diode steering relies on the principle that under certain conditions a diode when biased properly can act as a switch for AC signals. Typically these are low level signals although a company located right here where my laboratory is located (Newbury Park, CA) makes high power RF capable diode switches -- these are like watts not microwatts. But for higher power levels (and most ham budgets) a relay does the job. I purchased a stock of surplus micro-sized relays and so that will be my option.
7. We are now circling back to our Arduino and its control capability. In several transceivers I have used switches for input and for controlling the switching of the BPF's and LPF's. In the FPM-5 I used a two pole 6 position band switch. One pole provide input to the Arduino to change bands and the second pole powered on the appropriate relays commensurate with the band chosen. In the Big Kahuna rig a simple DPDT switch did the same job. In my KWM-4 I took advantage of the K5BCQ controller that produced a 3 digit BCD code as you changed memory channels. Not knowing any better , I took the 3 digit decode and decoded it using a 74 series chip that took in BCD and the output was a digital pin that went high with an open collector. The output from the IC fed a PFET that powered on the relays in the KWM-4. Later I found it could have been done with a single IC --a CD4028 -- same principle as what I designed. So we could generate a 2 or 3 digit code -- 2  = 2^2 = 4 possibilities and 3 = 2^3 = 8 possibilities and decode those for the band switching. Now we could just take an output from an Arduino pin  and "hot up" a 2N3904 and switch the relays. The uBitx from VU2ESE takes this one step further --it reads the frequency internally generated and automatically switches in the proper relays. In the final analysis I will use either the DPDT or a real band switch. Your choice. Lots of possibilities. [For those who lurk the EMRFD and uBitx forums --the decode switching was done 5 years ago by Pete the Genius.]

 

Today's journey was to explore some of changes we will be making to the original design and what we have dubbed the IC Transceiver. Essentially the IC mainboard will remain intact.

1. The receiver front end will have switchable Band Pass Filters.
2. The Driver stage will use the J310's configured as a DGM and the driver will be a BS170. This stage  will have switchable Band Pass and Low Pass filters.
3. Micro-sized relays will provide the signal switching/steering except for the diode steering on the mainboard.
4. The Final will be an IRF510 and have switchable Low Pass Filters.
5. The Arduino Nano & Si5351 will provide the LO and BFO Signals.
6. Band  switching will be either a DPDT Toggle Switch or Rotary Switch.

Stay Tuned there are exciting things happening.

73's
Pete N6QW

1/11/2018 ~ More on Copper Coated Vector Board .

Firstly here is where you can purchase the Copper board. Yes it is expensive --about $28 for a piece. But if you follow the process -- you could likely get three mainboards out of a single piece. [DigiKey is the supplier.]

 

Buy Single Sided Copper Vector Board Here

 

Now I have also done work with this type of board using Surface Mount Devices and the following two photos should expand your mind to see the possibilities. Once again Pete, The Genius is ahead of the curve. The process starts with a Fine Point Sharpie Pen and connecting the dots of the areas where you want to create an island. Next using a pencil draw a couple of guidelines around the area identified, which is then followed using a steel square and exacto knife remove the area between the guidelines. Leave at least one open hole in the island so you can connect wiring. [Yes Virginia this was done seven years ago and not invented last week by an OBTE on the EMRFD or uBitx Reflectors.]

In case you haven't guessed the hole spacing is 0.100 inch which makes it ideal for SMD application using the larger size 1208 parts.

This approach affords you the opportunity to rapidly prototype a circuit using short direct connections and a solid ground plane provide excellent RF properties. The other distinct advantage is that should you need to shield circuits a piece of scrap PC Board can be soldered directly to the mainboard. I have found it necessary at times to provide additional shielding and it was a simple matter to simply solder the shields in place. 

 

Stay tuned as we quickly move along with these projects -- you need to start drinking energy drinks and lots of coffee to keep up.

 

73's

Pete N6QW

 

1/10/2018 ~ More Examples of Single Sided Copper Vector Board used in my Rigs.

Keep in mind short direct connections and a common ground plane are always the "best" approach when building RF circuits. Tell me when it is not? There are probably one or two OBTE who will tell you they heard something third hand on the EMRFD reflector that it was not --my response consider the source.

 

In 2007 (that was 11 years ago) I started building transceivers using a common IF frequency ~ 4.9152 MHz and at the same time was actively pursuing an elusive goal of a shirt pocket sized SSB transceiver. I have come close to getting to the shirt pocket SSB goal; but not the final goal --one built entirely in an Altoids tin --maybe in 2018?

 

One of the 1st attempts was a 17 Meter SSB transceiver and like many of my projects I built two versions --the first typically looks like crap and is a true prototype. The second builds usually incorporate the "ahh" moments where you realize the better way. The K1BQT 2nd build will take advantage of what I learned from the 1st build.

 

The 17M  transceiver used a couple of innovative approaches. First using the 4.9152 MHz IF places the LO above the incoming at around 23 MHz. For the OBTE -- 23.04 - 4.9152 = 18.1248 MHz which is of course right in the middle of the phone band on 17 Meters. So how does one get to 23.04 MHz. The main frequency control is a VXO (variable Crystal Oscillator). Using several crystals in parallel configured as a Super VXO it is possible to move the frequency 10 to 30 KHz and thus you have a VFO like action using crystals.

 

The icing on the cake is the number of cheap computer crystal available to us. In this case, one of the stock frequencies is 11.520 MHz. The OBTE will quickly say --hey that is not 23 MHz. But if you use a diode frequency doubler (Thanks to W7ZOI) you can turn that 11.520 into 23.04 MHz. Now the real beauty is that what is ever changed in frequency at 11.52 MHz is doubled. So a 10 KHz swing at 11.52 MHz is now a 20 KHz swing at the output of the doubler circuit.

 

But I soon found that I did not have full coverage of 17 Meters. Thus a second set of crystals was custom ordered (ouch $50) and using a small relay I could switch the bank of crystals used in the VXO. Now with four crystals I can cover almost all of 17 Meters. I am missing a 6 KHz of coverage from about 18.141 to 18.147 MHz. Keep in mind this pre-dates the Si5351 and now $20 would give you full coverage with a Color Display -- but again this was 11 years ago. I may yet retrofit this rig --maybe with a 1/2 size OLED.

 

 

The above photos show how the single sided board was used for the 17 Meter  transceiver. Two things came from this 17 Meter project which were used about 4 years later in the shirt pocket transceiver on 20 Meters. The two items are the single sided copper vector board and the crystal switched VXO. Actually I should also include --the same IF frequency 4.9152 MHz was used in both rigs! The 20 Meter Shirt Pocket Rig photos (V1 and V2) are shown below.

 

Again the real advantages with the single sided board are short direct connections and the common ground plane. Today we have seen two examples of transceivers that were built using the single sided copper vector board. Also don't discount the crystal switched VXO as a LO source and the choice of 4.9152 MHz for a homebrew Crystal Filter. [If this choice of IF was good enough for Elecraft in the K2 why not in your rig.]

 

I sense the excitement building --hang in there as what I am covering now will be very useful if you decide to build the IC Transceiver. Some other parts you need to start finding --aluminum spacers with 4-40 threads. Look for 1/4 inch and 1/2 inch high spacers. The initial size goal for the mainboard is 4.5 X 6 inches. I will know more once I go through the iterative process of parts layout.

BTW in case you would like to see the documentation for the 17 Meter Transceiver see the link below:

 http://www.jessystems.com/morexcvrs.html

 

 

Yes Virginia, in addition to there being a Santa Claus there are hams scratch building real homebrew transceivers and the 17 Meter/ 20 Meter projects are original designs. So what are you waiting for --get off that couch and start building!

 

73's

Pete N6QW

 

1/09/2018 ~ Alternate Part Sources for the IC Transceiver. Also Tribal Knowledge on the Construction Practices to Build the Rig.

I love it when someone can find better parts bargains for projects and so it is with my friend Bob, N7SUR. He advised me that the MC1350 @ $2.50 and the MC1496 @ $1.35 can be purchased from Dan's Small Parts in Missoula, Montana. Dan can be found via Google and indeed has a lot of hard to find parts and some amazing prices.

 

Several years ago I purchased some vertical Style S Meters from Dan and these can be seen on my Belthorn III and Big Kahuna SSB Transceivers. The cost was very reasonable. May need to look to see if he still has those meters.

About 10 years ago I did build the K1BQT transceiver for 20 Meters and was delighted with its performance. That rig was given to another ham and now my desire to build a second unit. But this one will be a departure from my extensive use of the CNC Mill as it will use a technique that is quite excellent and not Manhattan nor Isolated Pads. The construction by the way is probably as fast or faster than having a specially fabricated circuit board.

 

Vector (as in Vector Board) makes a single sided copper Vector board and comes in sheets like 4.5 inches by 17 inches long. It is not cheap but one piece is enough for several projects. The beauty of this board is that the top side is a common ground plane. So any connections to ground are simply soldered to the top of the board. Below is the W7ZOI HYCAS IF amplifier strip/Product Detector  as built for my JABOM Transceiver project. Once it was built and tested I soldered a copper strips around the sides to form a copper box enclosure. There was a trick here. The finished board was mounted on aluminum spacers during the soldering of the copper sides. Now when you are done the whole assembly can be screwed down to the chassis base plate. The second photo shows how the point to point wiring was done on the under side (insulated) of the single side board. Those who like to pick things apart (as they do on the EMRFD and uBitx Reflectors) there is only one connection that crosses over the wiring. [Further note -- this project was built 7 years ago and described in a QRP Quarterly Article. Pete the Genius was once again breaking new ground!]

 

 

 

Now I am going to share some Tribal Knowledge about how to make the part layout and minimize cross overs and have the parts laid out to minimize connections. In the case of the HYCAS it was an iterative (meaning doing several times) process that first starts with a piece of PLAIN (no copper) vector board and the schematic that you will use. Liberal use of small wood blocks and masking tape facilitates the process. Another tool is a metal cookie baking pan that is about 12 X 18 inches. Typically these pans only have about a 1/2 inch high side.

 

Start first by taping the wood blocks to the cookie pan base spaced slightly shorter than your plain vector board. Next tape the board to the wood blocks  and assuming the builder knows where is pin 1 start by inserting one of the IC sockets (yes 14 pin DIP Machined Pin Sockets, MPS) into the board. Using the schematic insert parts into the board so that you get a compact layout and visually see how to minimize connections and cross overs. Take small sections at a time to do this. When you are satisfied that you have all of the parts on the board for that section and that the connections are minimized and the shortest possible connections are used. Take a photo with you phone camera. You will use this photo to do the final layout on the copper board.

 

1. Now as to the why use the plain board for the initial layout --it is the oil and acid on your hands. The trick is to minimize the physical handling of the final board to minimize any discoloration and difficulty soldering based on corrosion build up. You might consider wearing rubber surgical gloves during the final soldering process. I do.
2. The plain board with the cookie pan enables you to stop work without having to clear off everything and just moving the pan out of the way keeps everything neat and tidy. It also helps prevent the loss of parts as the pan acts as a captive mechanism.
3. The process really helps you understand the circuit elements as it goes beyond just stuffing a board with parts like the OBTE frequently experience without the knowing the why.
4. The wood block are about 1 inch high which lets you push through the leaded components so that they are flush with the plain vector board. The blocks are a must!!!!

An important tool must be built prior to working on the final single sided copper board and this is shown below and is comprised of two parts. A 1/8 inch knob and a 1/8 inch drill bit. Resist simply taking a 1/4 inch knob and a 1/4 inch drill bit like the OBTE would do. This tool is used to remove a small amount of the copper material around a part that will be placed on the board and not grounded, meaning it will be connected to other components on the underside of the board. Before you insert any non-grounded component, twist the drill bit a couple of times to remove the copper around the penetration hole and then inspect the whole to assure no burrs remain.

 

The reason the 1/4 inch should not be used is that too much copper would be removed. You want to remove just enough so the parts are not shorted to ground but not too much to reduce the ground plane effect. In the case of the IC sockets I remove copper for every pin (14 or 8) and you will also find since I use machined pin sockets (a must) that each hole for the DIP sockets must be slightly enlarged to accept the machined pin sockets. If you don't know what a machined pin socket is --turn off your soldering iron and take up another hobby. The why of the MPS is to assure the socket doesn't float around and that you have a solid pin to affix components to and finally a solid soldering base.

 

 

 

 

 

This is a good place to stop --today we gave you an alternate source for the IC's, introduced you to the single side copper PC Board method of construction and shown a special tool you will need to build the project.

 

73's

Pete, N6QW

 

1/08/2018 ~ Getting a "Head Start" on the K1BQT Rig

So OK you got some Amazon Gift Cards for Christmas and are wondering where to spend the loot. The very 1st thing you do is go to Bill's, N2CQR, SolderSmoke blog and click on the Amazon Link and begin your shopping for some of the parts to build this rig.

 

I just know there are many homebrewer's who simply can't wait to build this amazing rig --even before me. So if you have that kind of itch to scratch, then visit my website http://www.n6qw.com 

 

On that site you will find an amazing array of projects from the N6QW Laboratories and only one or two even hint of being Bitx related.

 

The project you want to view in detail is "The Big Kahuna" which is extensively documented. There are three pieces from that project that will be used with the IC Transceiver (That is now what I am calling K1BQT;'s transceiver.)

 

The three pieces are:

1. The Arduino Sketch for the Big Kahuna uses the 9.0 MHz IF and thus already puts you in the ball park. This sketch has you use a DPDT toggle Switch for band change with 1/2 the switch providing the input to the Arduino to change bands and the other half provides voltage to the relay banks to select the proper set of matching Band Pass and Low Pass Filters in sync with band showing up on the display. The display is the very large 320 X 240 and offers some possibilities for displaying other data.
2. Now Genius Guy that I am --the sketch includes the code for 5 Bands which are linked to five pins on the Arduino -- thus by selecting the proper pins you can steer your build to what ever two bands you chose. Like 80/20 or 80/40 or 20/15. Guys with a 9 MHz IF I have chosen to stay away with anything saying 17 Meters. Now if you change the Filter Frequency say to 8 MHz then you can use 17M; BUT you will have to change the numerical data in the code to account for the IF offset and the new BFO frequencies. You can do that --don't ask me to do it. The wiring of the display and the level shifter (CD4050) is embedded in the sketch.
3. The Band Pass Filter Data for the 20/40 selection is in the Big Kahuna complete with LT Spice Simulation, plots of the curves and the component values. If you chose other bands you will need to develop the schematics -- the LT Spice schematics should be a clue for you. Don't ask me to do it
4. The Low Pass Filter Data is a lift from W3NQN so you have the numerical data for the various ham bands. The calculation of the turns for other bands is your exercise not mine. This is a good time to venture out on your own.

So having these three pieces already available eliminates about 35% of the project that will need development. We will endeavor to use other N6QW building blocks such as the driver stage [EMRFD lift] and the IRF510. Thus even more hardware can be built ahead of the main IC board.

 

73's

Pete N6QW

1/07/2018 ~ A Link to the 1985 HR Issue

Thanks to another Pete in very cold Illinois he found a link to the issue where the original article appeared.

http://cahabatechnology.com/aa4pg/hrmag/hamradiomag/Ham%20Radio%20Magazine%201985%20%20Issues%201-12/11%20November%201985.pdf

Thanks Pete!

73's
Pete N6QW

1/06/2018 ~ Coming Up in the Queue - Start Planning Your Moves and Locating Parts! (See Block Diagram Add)

 

K1BQT's XCVR from November 1985 ~ With 2018 Updates!

 

 

 

Visit Jameco Electronics http://www.jameco.com and you can find the following critical parts

 

• MC1350 IF Chip P/N 24942 Price $3.95
• MC1496 (four required) Double Balanced Mixer P/N 23211 Price $1.95
• IRFD1Z3 (not available anywhere) But I believe a BS170 will work

For the IF Filter (9.0 MHz) I will be using the Crystal Filter from the GQRP club. I believe they still have a very small quantity left in the bins. You will also need to find some 40673 Dual Gate MOSFETs or you can use two J310's configured like a DGM. The Final Amp can be a IRF510 (also at Jameco). This will be a two band radio --a simple toggle switch for your two bands of choice like 80/20 Meters or 40/20 Meters. Guys forget 17 Meters with a 9 MHz IF. My design will have separate band pass filters for the two bands.

 

K1BQT's design has a key feature (maybe that is where I got the idea for my last 2018 project) and that is the MC1350 IF amp chip is used on both transmit and receive. Also his rig not only had AGC but ALC -- just a few more parts. Like in my last rig --it will have a cool analog S Meter OR the S meter included on the Color TFT.

 

The updating will include the Arduino Nano, Si5351 and the 160X128 Color TFT display.

 

This is not the very next rig on the bench; but the info is being provided early so you can start to get organized. The first trick is finding the article. The Ham Radio Magazines were free on line. But someone evidently filed a law suit and they were removed.

Found: http://cahabatechnology.com/aa4pg/hrmag/hamradiomag/Ham%20Radio%20Magazine%201985%20%20Issues%201-12/11%20November%201985.pdf

I will create schematics of what I build since it is different than the original article. This should not violate any copyright issues. BTW the original article used the TO-5 Version of the MC1496 and the ones being sold are the 14 Pin DIP --not to worry I will provide the magic decoder ring.

Below is a block diagram of how this new transceiver (new for 2018) might be fashioned. The building blocks are pretty standard.

A Post Script --the Ham Radio Magazine cost but $2.50 and unlike the ham radio magazines of today did not focus on contests and operating news -- this was a publication for homebrewer's. (For the box top extra's this means something other than appliance operating your latest ICOM or Yaesu)

Post Post Script: On eBay currently is a IF board out of a commercial radio (being sold from Israel) that has three 9 MHz Filters on the board. I had an earlier posting about a rig now in work that uses two of the filters (USB/LSB). That rig is still in the queue for 2018. The board from one of the sellers costs $34 including the shipping . But also on the board are the critical MC1350 and several MC1496's. So this board already contains many of the parts. NOW a huge caution if you are unskilled with a soldering iron and the removal of parts from a manufactured board --this is not a good option for you for the parts other than the filters.

 

73's

Pete N6QW

1/05/2018 ~ Listening to the new Rig!

 

The 1st SSB Transceiver of 2018 from N6QW ~ 35 years in the Making!

 

 

 

 

It only took 35 years but we now have achieved our goal. High marks for an Old/New Technology Rig. Get off that couch and start building --we soon will moving forward on another new rig --or I should say and old rig that has been reformed! You got to keep up.

 

73's

Pete N6QW

1/03/2018 ~ It is alive!

I am happy to report the 1st QSO with the reformed rig and it was with a station in Hawaii, Thanks Norm for the 1/2 hour QSO. (An oddity in our 5X9 running a FLEX 6700 rapid fire QSO Mode.)

The D-104 microphone gives you an idea of the size. I was also constrained by what holes in the front and back panels existed as a result of the original build and several reincarnations. The upgraded changes include USB/LSB select, 128X128 Color TFT, a new driver stage (2N3904/BD139) and the IRF510 as a final amp. the IF is at 9.0 MHz.

 

Some changes to the main board include removing the homebrew diode ring single balanced mixer that was used as the Product Detector on receive and as the transmit mixer stage on transmit. A TUF-1 replaced all of that hardware. I also removed the homebrew diode ring balanced modulator and replaced that with an ADE-1. Man the new devices sure replaces a lot of old hardware.

 

I mentioned in an earlier post one of the problems I found with the original build -- a bad diode in the single balanced mixer used as the PD / Transmit mixer --this is what prompted the shift to the TUF-1 and while I was at it I changed out the original balanced modulator to the ADE-1. The TUF-1 is just below the GQRP Crystal Filter and the ADE-1 is mounted on a vertical board just behind the panel meter. You will see some open space behind the vertical board --all of the was formerly jam packed with Balanced Modulator components. The microphone amp was a 741 ( a staple for 1980's transceivers). Just behind the vertical balanced modulator is a brass shielded enclosure that originally housed the BFO. In that now resides a relay that switches power to the receive and transmit circuits that do not run continuously. BTW I bought these relays which have 12 VDC coils and are SPDT capable of handing 8 amps --from Jameco Eeletronics on closeout -- 10 for $6

 

 

Mind you again this was originally built in the 1980's and the architecture relied heavily on diode switching. On the receive side the 1st stage is a Dual Gate MOSFET mixer which was diode steered through the IF chain. The other half of the diode steering was the Balanced Modulator.

 

The IF chain used a pair of 2N3904's on either side of the 9.0 MHz Filter similar to what ON5FE used in his 1970's Transceiver IF Module. That stage is followed by a Motorola MC1350. This device was chosen so I could add AGC on receive and an S Meter. On transmit this stage has fixed gain applied. Following the MC1350 is the TUF-1 where on receive the BFO is diode steered and we have product detection where from there it goes on to the audio amp stage (2N3904 / LM386-3). On Transmit the LO is diode steered to the TUF-1 and this now is the transmit mixer.

 

Following the TUF-1 (on transmit) is a 20M Band Pass Filter and then on to a 2N5179 RF amp. The 2N5179 was the Hayward device of choice in many of his SSDRA circuits. From the mainboard we have the driver stage and the final amplifier.

 

One challenge I had was space -- the box was already pre-determined! Where was I to mount the TR relay and the Low Pass Filter. My mechanical engineer son (the one with the super knack) has decoded what I want for Birthdays and Christmas presents. Yes, Hardware! Thanks to son Nick I am well stocked on nuts, bolts, spacers and connectors! Here is how I resolved the TR relay and external amplifier switching. I used four 1 inch standoffs to mount the small circuit board to the same mounting holes as the copax connector. Right near that is the small circuit board built on the CNC that is the LPF. The connections are short and the assemblies fit in the cramped quarters

 

 

Below are a couple of shots of the Final Amp board (IRF510). I have designed a standard RF amp Circuit board that can accommodate most any RF device that comes in the TO-220 package style. Thus some of the island squares are not used for the IRF510. When I need a new board --chuck up a piece of stock in the CNC and press "Start".

 

 

I will continue to fine tune this rig as there are some functions the need to be completed. I have a small push button on the front panel that will initiate the Tune Tone. That wiring needs to be installed as well as build the three stage RC filter to take the square wave 988 Hz tone generated by the Arduino and convert that to something close to a sine wave which is then routed to the balanced modulator for Tune Up.

 

73's

Pete N6QW

Well these are only new if you consider that they will be/are newly reformed old projects.

I often mention that I have two boxes of projects ~ one very large box with ones that sorta worked, worked once and died, never worked and finally never would work as configured. The other much smaller box are ones that work --and nicely I might add. So I have dug really deep into the very large box and pulled out three that in their present state are not air worthy; but the goal is to make them so. Along the way we will add goodies like digital VFO's, Color TFT display and only commercial filters. Frankly I have better things to do than screw around with Dishal software.

 

The first which I have already started is about 75% there and shown below. This was a solid state rig built in the early 80's and while it did work --was never quite what I thought is should be. Recently I found out why. I will cover that in a future posting.

 

By the way most of the stuff that is in the large box was built using the SSDRA [Solid State Design for the Radio Amateur]. Do what you can but get yourself a copy even if that means selling your EMRFD. I just think for someone who would like to start building radio projects EMRFD is not the 1st choice and SSDRA will get you farther and faster along the learning curve. Just my opinion but there is a sound basis for that opinion. I have found a good use for my EMRFD --it is a great bookend!

 

 

The above rig started life as a 20 Meter QRP rig with an analog VFO, Crystal BFO, 9 MHz KVG Filter and an IRF510 Final. This was not someone else's design but something I conjured up using building blocks taken from various publications and reference books. This rig was built Pre-Internet. Many of the circuit blocks are from Hayward and DeMaw and some pulled out of thin air.

 

I will document what I did and how the radio was constructed --for now just drool over the photo.

 

BTW I am now in therapy after participating briefly in the Bitx20.io forum. I have since sworn off reading any more posts from that group. The uBitx is a superb rig and I will stop there!

 

Happy New Year!

 

73's

Pete N6QW

 

The uBitx is inhaling RF at N6QW

Catch the Wave ~~~ The uBitx is Alive!

12/23/2017 ~ On the Air QSO with the uBitx!

The uBitx is a real winner --so get off your butt and order one! Listen to the on the air comments and also make the N6QW linear amplifier hack as you will need that during poor band conditions. The fact that you can run a linear amp without hiccups and burps is a testament to the design! Thank you Farhan.

The "Cool Juliano Blue" LCD has to be a factor in how good it sounds! I am also told that the blue display is a major factor in the fight against global warming. OOps forgot there is no global warming or so our leader tells us.

 

Merry Christmas and Happy New Year to All.

 

 

 

PS. When you watch the video note that the guy with the FLEX6500 said you sound good and even compared what he spent and what the uBitx costs. The uBitx stands tall with the Big Dogs! Keep in mind my "hack' to add a linear amplifier control. Anymore out here on the left coast when operating on 40 Meters --QRP is something that starts around 200 Watts!

 

For this QSO I was running two amps -- one to get me to 100 watts and then the SB-200 that puts out in excess of 600 watts. N6QW (me) has a you tube video on the rebuild of the SB-200. The reason I can get more juice out of my SB-200 is the power supply! The supply has a Peter Dahl transformer and an upgraded filter bank. The voltage sag on key down is far better than with the stock heathkit supply. More volts and current = more watts. Keep you tune up short --using a pulsed method saves your tubes!

 

 



 

 12/22/2017 ~ A New Look for the uBitx!

So ok you have built your uBitx and there it is in all its glory with a display that makes me think of "seasick green". About five minutes worth of work and the moth turns into a butterfly. So OK C'mon admit it Cool Juliano Blue is Better!

 

73's

Pete N6QW

 

 

12/20/2017 ~ More Feedback on the uBitx!

The main feedback -- Get One! The price is amazing and the performance is excellent. I have made close to two dozen contacts and the signal reports have been excellent. Are there some things I would like to see "hacked" --yes and I specifically know that these are being worked. These "like to see" changes in no way take away from the amazing functionality; but represent personal preferences based on how I like things. Needless to say the open source nature of the software AND the intent of the designer for this to be an experimental platform that is to be modified speaks volumes about rig.

 

Pete's Christmas "Wish List" for the uBitx:

 

1. Color TFT Display. Not only would this be cosmetically appealing but more importantly it offers more real estate (viewing area) for displaying parameters and providing status. Some adds -- A/B VFO frequencies, RIT On. SWR, Battery Voltage, S Meter. It is amazing how 32 positions were used for displaying data on the LCD -- the Color TFT would give an order of magnitude increase in the data displayed. I know of several projects already in work to do this.
2. I suffer from FFS [Fat Finger Syndrome] and the variable rate tuning functionality while some would like, is totally incompatible with my FFS affliction. No matter how hard I try not to crank the dial -- I usually end up 100 KHz past where I want to QSY. It is difficult for me to relearn just lightly touching the dial to change frequency. Since you already have a menu selection to make large frequency excursions my personal desires would be to have a fixed tuning rate of 100 Hz and two additional selections of say 1 KHz and 10 Hz. The CW aficionado's would undoubtedly love the 10 Hz. You also need the 10 Hertz out here on the left coast when the guy with the 72 Inch LCD screen is mated to his FLEX6700 and he tells you are off frequency by 20 Hz --you will never be able to satisfy him with a 50 Hz move!  

Please note these items are personal desires and that my comments have nothing to do with how it receives or how it sounds one the other end. High Marks in these two areas.

 

Oh I posted some hack info on the Bitx Hack Page -- one was the control of an external linear amp so you can add some fire to the wire is primarily intended for SSB operation as you are connected to the PTT switch. In the CW mode the uBitx is placed into transmit by means other than tripping the PTT circuit. So don't be surprised if you make that mod --it will not turn on your big 1.5 KW amp in CW. 

 

Some 29 years ago in the December 89 / January 90 QST Wes Hayward W7ZOI had an amazing project -- a 20 Meter QRP SSB/CW transceiver. I actually have built two of these transceivers. One "shortcoming" if you could ever call a W7ZOI project as having a short coming -- to operate CW you had to manually do it by holding down the PTT switch and then key away. I fixed that problem by building in a keying circuit that when you hit the 1st dot, a reed relay closed the PTT. I did have to add some capacitance to hold in the PTT during key up -- but that was far better than having to hold in the PTT.

 

Since I don't operate CW (hardly ever) this was not seen as a problem for me with the uBitx. A possible fix so you could have 1.5 KW on CW --rig a foot switch to your big amp and do it like in the old days.

 

73's

Pete N6QW

 

 

12/19/2017~ NEW Hacks to the uBitx de N6QW

Add Safety Protection to your Finals -- There is no foldback current limiting with High SWR and thus an inline fuse is cheaper than a set of IRF510's

 

The 2nd hack is to switch on a linear amp using the uBitx PTT control. My uBitx now runs 600 Watts and that my friend is not QRP!

 

For details on implementing these hacks see http://www.hfsignals.com and click on the Bitx Hacks link.

 

You saw it first here from N6QW.

 

73's

Pete N6QW

 

 

 

***********************************************************************************

 

 

N6QW is on Hiatus which means he can build Rigs without interruption! The uBitx is on the air as of 12/17 and contacts were made on 20 and 40 Meters. It works!!!!

 

73's

Pete N6QW

 

 

 

 

 

A New SSB Transceiver for 2018

A New Transceiver for 2018

Build this transceiver for $120!

 

This transceiver will leap tall buildings in a single bound, will go faster than a speeding bullet and is stronger than cobalt steel. Save your Christmas money for this project.

The basic circuit uses the Plessey PNP NPN bilateral amplifier as found in EMRFD ahead and following the Crystal filters which are diode steered. I have found you can use 8 VDC versus the recommended 6 VDC and you see a significant gain improvement. Ahead and following the IF amp block are ADE-1's where on the front end it is used as the Rx Tx mixer stage. On the back end the ADE-1 is used as the Product Detector on receive and as the Balanced Modulator on transmit.

While this test setup used a signal 2N3904 as the Rx RF Amplifier the final configuration will have two J310's configured as a Dual Gate MOSFET. There will be two small communications relays that will switch signals so that on Rx it is the receiver RF amp and on Tx it will be the transmit Pre-Driver. I have used this approach on the Simpleceiver Plus SSB transceiver and the Teensy 3.5 SDR transceiver. It works well!!!!

The audio amplifier stage use an NE5534 driving an LM380. For the microphone amp the 2N3904 is pressed into service. The Driver is the 2N2222 followed by a BD139. The Final is an IRF510. The current plan is to have this as a two band transceiver ~ very likely 40 and 20 Meters.

 

 

 

 



 

 

 

 

73's

 

Pete N6QW



21st Century Homebrew SDR SSB Transceiver Project

Roll Your Own SDR SSB Transceiver

 

N6QW Moves Totally to the Dark Side of the Hobby!

11/27/2017 ~ Observations and 1st DX Contact

Today I wanted to spend a bit of time comparing the new SDR homebrew transceiver to "filter" type rigs I have built. First though I do want to share that I worked my very 1st DX station with the SDR rig and that was XF1IM who is in lower Baja California. The distance was 1600 miles running 100 watts. So I am beaming from ear to ear.

 

Firstly I do want to acknowledge once again the pioneering work of Charlie, ZL2CTM and his several you tube videos that got me kick started into rolling my own SDR rig. Notwithstanding I do have several SDR kit radios including several Softrocks and the Omnia based on the Peaberry --and even one that uses a Softrock with a Raspberry Pi. So I am not brand new to SDR, but I am new to rolling my own.

 

Above all there seems to be a clarity to the signals and perhaps that is because the bandwidth may be a bit wider. It was even suggested to me (by an appliance operator no less) that I should open up the bandwidth to 3.5 kHz. Well friend that may be problematic. But the sound is fuller. It does have presence and brightness with no "yellowy sounds" in the mid-range.

 

I also note that signals seem to pop out of nowhere. Boom no signal and very quiet then suddenly a rock crushing signal. There was an occasional you are 20 hertz low and I disregarded that since I rechecked --and that station was 20 Hertz high.

 

All in all there is very little hardware as such and in going over the cost --about $100 with half of that in the Teensy 3.5 and Codec board. So it does cost almost 2X the Bitx and you do have to build it yourself; but there are opportunities beyond the basic radio from India. Those are mainly in adding software functionality like variable filtering (you can decide how many filters and bandwidths you would like). Charlie has developed some software so you can watch the FFT display of Frequency Spectrum -- that would be hard to do with the Bitx. So think about it -- a far greater capability for about $41 more. There is a wave coming and we are the beneficiaries of the low cost technological wonders.

 

73's

Pete N6QW

11/26/2017 ~ More Refinements & More Contacts.

 

That is the pure beauty of our hobby -- you make contacts and you get feedback on your signal. I did get some feedback about signal quality that appeared to be related to signal distortion on large voice peaks. It was not RF feedback; but more in line of things running "too hot". [Not hot in the sense of heat but rather too much gain".] It also appears there was somewhat of a restricted voice in that the signal sounded a bit narrow.

 

To address these issues I went back to Charlie's original low pass filter (as I would have to design a new Band Pass filter that was a bit wider) and a clue from one of the QSO's was what happened when I reduced the gain on the J310's in the combo Rx Tx amp stage. The report back was that the distortion on peaks had almost disappeared. Big Clue. But that also reduced the Rx RF gain significantly. So I had to strike some sort of balance on the gain settings between receive and transmit.

 

In the EMRFD stage the input had a 5.5 dB T Type attenuator pad as I found over several earlier builds this tremendously helped the stability of the stage. Thus a plan was formulated to increase the size of the pad from the 5.5 dB to 10db and this enabled me to increase the gain on the Rx RF Amp side by about 5 dB overall. Thus we had  best of all worlds. So the balance was struck. Next I went into the software and reduced the microphone gain which was set at 40 down to 30. The full gain setting is 60 --so we are at half gain versus 2/3. As a final adjustment I tweaked the bias level of the IRF 510 to about 4 volts --it was running about 3.6 VDC.

 

In listening to the signal on an outboard receiver and then looking at the scope pattern I could tell that the signal quality had greatly improved -- and I still was getting 100 watts out with the outboard amp. Three contacts, one in Colorado and two local contacts including one with my friend Ben AI6YR verified that all was good in the hood. I also took the time to "clean up" some of the wiring including running some leads under the base PC Board. That clean can be seen in the photo below.

 

 

The next goal is to finalize the switching circuits and get everything into an enclosure. I then want to turn my attention to learning more about the software and some upgrades in functionality like adding the 160X128 Color TFT display,  switchable USB/LSB and a TONE for Tune Up whish is pretty much standard in all N6QW Homebrew Rigs. Yet another upgrade in the software is switchable filters for SSB and CW.

 

73's

Pete N6QW

The next goal is to get this in a box and finalize the switching and control ciruits

11/22/2017 ~ Adding the RF Power Amplifier Stage

 

DRUM ROLL ~ 1st Contact with K8NG

As luck would have it I heard K8NG calling CQ on 7.213 MHz at 1510 PST and gave him a shout. Boom he came back to me with a report of 5X3, 5X4. Mac, K8NG is located in Duck Creek Utah and interestingly enough one of the video made with the Simpleceiver Plus SSB was made with Chris, KF6FZY -- also in Duck Creek. There must be a pipeline. Mac reported the signal sounded fine albeit with a bit of restricted audio. That reflects the narrow band pass filter software that I installed. I was running 5 watts with the IRF510 and no amps. the antenna was my usual droopy dipole. A great day. It doesn't get any better.

 

73's

Pete N6QW

_________________________________________________________________________________ 

I went over to the Simpleceiver Plus Prototype and temporarily liberated the Driver, Final and Low Pass Filter stages and connected them to the Teensy SDR. I got about 6 watts out and was pleased to see this work.

 

I am lacking a relay to make this a fully functional Transceiver so for these test all was hardwired. I am overcome by getting ready for the gang that is coming in for Turkey Day--so I will have to curtail any activity for a few days. You can also visit my cooking website as some of the recipes on the site will be the fare for Thursday. www.pastapete.com

 

 

73's

Pete N6QW

 

 

11/21/2017 ~ Relays added to the Front End Board

If you look closely at the J310's RF Amplifier you will see a couple of 12 VDC SPDT Communications relays that I purchased from All Electronics.

 

Look closely as these are listed as micro-miniature relays.  These are made by Fujitsu and are the BRD series. These bought in quantities can be had for 35 cents each. The contacts are good for 2 amps. A little super glue and they are solidly mounted to the PC Board. I tested this configuration and it works FB. The relays can be seen along the upper right hand corner of the board.

 

 

 

Charlie, ZL2CTM shared with me how to change the Microphone Gain and I have been able to do that successfully. Stay tuned --we may be not too far off from some on the air tests.

 

73's

Pete N6QW

 

 

11/20/2017 ~ First Transmit Test and More Listening Tests

 

 

 

The transmit concept works with my front end board. The Modem Transformers are also now a proven concept on transmit. I need to find a way to adjust the Microphone gain and to look in more detail the output SSB Envelope. But this is getting exciting.

 

 

73's

PeteN6QW

 

11/19/2017 ~ Block Diagram of the SDR Front End

 

 

11/18/2017 ~ We are 98% there ... Listen to the Video

 

 

 

 

 

This video is a great leap up from where we started. I think we have some positive trends going here. My next task is to get it t work on Transmit and then we can see if we can make a Transceiver from these two boards.

 

73's

Pete N6QW

 

 

11/17/2017 ~ The Problem Appears to be Fixed

Aside from installing a new Codec board and taking a tip from Hans Summers g0upl, today the 600 Ohm to 600 Ohm Isolation transformers arrived and were installed. That cured the hum problem and I will make another video to demonstrate the improvement. The Trick is to separate the grounds. Thanks Hans!

 

 

 

Shown above are the two Isolation transformers (sold as Modem Transformers from Jameco Electronics -- Triad Transformer is the Manufacturer-- about $6 each). Phasing is important and that is why you see the dots (as supplied) on the transformers. Hard to believe that what you see above is the front end, the quadrature LO, phase splitter  and the I & Q Detectors. The audio amp (2N3904/LM-386-3) is also on this board.

 

In passing I do know that the I & Q is working very well. After modifying this board and the Teeny 3.5 board to add the isolation transformers I powered up the unit --and all I was receiving was USB -- Inadvertently I had the I & Q reversed.

 

The two black wires going to the ADE-1's is actually a chunk of shielded cable from a pair of defunct Sony Walkman earbuds. I made it extra long just in case I did that. I will now trim the wires and tidy things up. On either side of the J310's RF amp stage I will be adding a couple of relays on the RF Amp to use this circuit as the Rx RF Amp and as the Tx RF Pre-Amp just like in the Simpleceiver Plus V2.0. I purposely left space on this board to do that. You still need to have the isolator installed on the audio output out of the Teensy 3.5.

 

Can't wait to get this working as a transceiver.

 

73's

Pete N6QW

11/16/2017 ~ Some Progress on Fixing the Whine Burble Noise

 

Part of the problem was the Teensy Codec Board. I had a second board and the above video shows the improvement. We are not out of the woods yet. There is still a bit of background hum which may be resolved with the addition of the 600 Ohm to 600 Ohm Isolating transformers on the front end output similar to what Hans Summers has done with his QRP Labs receiver board. I already have a small fortune in hardware so a few more bucks almost seems like pocket change. The flies in the face of my 1st station which cost me $20 in 1959. I had to mow a lot of lawns to amass $20.

 

73's

Pete N6QW

 

With a large Tip Of The Cap to Charlie Morris ZL2CTM who has done some pioneering work in building SDR SSB Transceivers as evidenced by his superb videos on You Tube --I decided to try my hand at replicating Charlie's work. ZL2CTM has most kindly provided me a great deal of assistance and supplied the all important sketch code and many photos and schematics that he used.

 

Charlie has been successful with his rig. But I have not been so lucky. I simply cannot put my finger on the root cause but in hopes of those more skilled at this SDR stuff will immediately know the answer. View the video and "Tell Me What You Think".

 

The main issue is the terrible background noise that is present on the audio output. If the "whine and burbling background noise" could be resolved --this would be one heck of a rig.

 

By way of background the rig consists of a front end comprised of a pair of J310's configured as a DGM RF amplifier, a 40M Band Pass Filter, a homebrew ferrite core balun signal splitter, two ADE-1's as the I & Q Detectors and a SN74AC74 that is used as the divide by 4 quadrature LO. Also on the main board is an audio amplifier using the 2N3904 and LM386-3.

 

The SDR board has the Teensy 3.5, the Audio Codec Board, the Si5351 and some relay switching so the Line In and Line Out I & Q can be routed to/from the board. For a Display I am using the 1 inch square OLED.

 

After connecting everything up and listening -- it was awful and a terrible whine and burbling noise was evident which called for a disciplined trouble shooting process. The first thing I did was hook up the front end as a Direct Conversion Receiver and routed the output of the I & Q Detectors to the Audio amp (1 channel at a time). The sound was crisp, clear and no evidence of any problems. While the SDR board was bypassed, I was using the LO signal from the Si5351 and the OLED for reading the frequency. Thus the clean signal was not impacted by any OLED noise and what also was evident -- nothing was coming through the Si5351. The outlier was the Teensy 3.5 and the Codec Board.

 

Steve Hartley g0fuw sent me an email about an event in the UK called YOTA which also had a link to a video about the event. (YOTA = Youngsters On The Air). After seeing what these youngsters were doing -- they probably have the answer. The problem is this "oldster" doesn't! Help????

 

I did pose the problem on the PJRC Forum (Teensy gang) and even contacted the head guru at Teensy -- aside from one response from the forum which was not helpful nothing else has been heard other than to sell me another piece of hardware while helpful did not totally resolve the issue. Help????

 



 

 

 

This project has been a frustration to me personally as I just don't know enough about the Teensy 3.5 to lay a finger on the problem. Perhaps it is not a bad device --but I upgraded to a Teensy 3.6 and the results were worse --an important clue that the problem is a Teensy hardware issue.

 

Has anyone reading this blog been successful with the Teensy 3.5 -- ZL2CTM has had good luck but he too is scratching his head.

 

 

73's

From the Dark Side

Pete. N6QW

Simpleceiver Plus Version 2 SSB Transceiver

V 2.0 of the Simpleceiver Plus SSB Transceiver

11/13/2017 ~ Last Posting on the Simpleceiver Plus SSB XCVR

 

 

Thanks for riding along but now it is time to move on --Perhaps Part 15 Low Power Neighborhood FM radio stations using a Arduino and Si5351 in an FM Mode much like VU2ESE. It is a whole new world out there. I can only hope the readers have enjoyed this project as much as I have.

 

n6qwradiogenius@gmail.com

 

73's

Pete N6QW

11/12/2017 ~ A Few More Photos Before Painting JuliYellow

Note new email address as of 11/12/2017:  n6qwradiogenius@gmail.com

 

 

 

 

An approach for indicating USB/LSB --The Red Square. Works for Me. So far have had a bout 10 contacts and the Rig is doing exceptionally well.

 

Pete

 

N6QW

11/11/2017 ~ On the Air QSO with KC6FZY.

The Simpleceiver Plus SSB Transceiver is nearly complete and the documentation will ultimately shift to my website http://www.n6qw.com. Most likely there will be no more posts about the project as I have been politely told -- enough Pete! Despite that input this rig is one of the better ones I have built.

 

 

 

73's

Pete N6QW

11/09/2017 ~ First QSO with the Simpleceiver Plus SSB V2.0

The wiring of the V2.0 was completed today and the very first QSO was coast to coast with WA3RSL, Frank in Appomattox, VA. The QSO was at 1445 PDT on 7188 kHz. Frank was running  a Yaesu FTdx3000 with an ACOM 1000 and a 5 element wire beam. On this end I was running the V2.0, the intermediate amp and the SB200. The Pout was close to 800 Watts and my usual antenna was the droopy dipole. WA3RSL was of course 5X9+ and I also got a 5X9 report --including a comment on the nice sounding audio.

 

 

Top View of the Simpleceiver Plus SSB V2.0

 

This is the Simpleceiver Plus V2.0 SSB Transceiver prior to painting and finishing off the case.

 

 

This project has turned out to be one of the best transceivers I have ever constructed -- and the circuitry is so simple. Stay tuned for more reports of on the air QSO's

 

73's

Pete N6QW

11/08/2017 ~ Simpleceiver Plus V2.0 Construction Photos

 First look at the front panel layout of the Simpleceiver Plus V2.10 SSB Transceiver being boxed up. Work remaining includes building the Low Pass Filter and the power relay switching wiring plus build the back panel. If we can get the LPF built we can do some on the air testing. I am impressed at the sensitivity and how good it sounds.

 This posting will now show some details of the V2.0 Build as we progress through the process. By way of review the V2.0 build consists of two PC boards which are stacked one above the other. Here is the breakdown of the two boards

 

 

Bottom Board. This is the main board consisting essentially of the following elements: The 40 Meter Band Pass Filter, The RxTx Mixer (ADE-1), The 9.0 MHz IF Amplifier block (two sets of J310'c configured as a Dual Gate MOSFET), The Product Detector/Balanced Modulator (ADE-1), The Audio Amplifier and The Microphone Amplifier. The IF Amplifier Block is relay switched so that the signal is passed through the block in the same direction on both transmit and receive. This one board forms the basis of the transceiver and all this circuitry is packed onto a board 4 X 6 inches.

 



The last photo show the board with all of the circuit blocks starting on the lower right side with the band pass filters moving to the lower left hand corner with the Surface Mount 2N3904 Microphone amplifier. The first photo shows the PC board on the bed of the CNC Mill. Noteworthy is that much of the wiring is routed underneath the PC Board which is mounted on the base plate using 1/4 inch aluminum pillars This really cleans up the wiring and helps with unintended coupling and feedback paths.

 

The top board is mounted on spacers that are about 1.25 inches above the main board. This board has the mounting space for the Si5351, The RxTx RF Amp Stage which again is relay switched to change the signal path so that is passes through the stage in the same direction on both transmit and receive. Following that stage is the EMRFD transmit driver block and finally the IRF510 final amplifier. Not seen is the aluminum plate that is 3 X 4 inches by 1/16 inch thick and forms the basis of the heat sink. This plate is mounted to PC board which has the cutout so that IRF510 is directly mounted to the plate. The overall box size now is about 4.375 inches wide by 8 inches long and 3 inches high.

 

The following photos show the top board and the component parts.

 

The above photo show the top board starting at the upper left corner with the space where the SI5351 will ne housed and below that is the relay switched RxTx amplifier stage consisting of two J310's configured as a Dual Gate MOSFET. In the lower right hand corner is the EMRFD Driver Stage with the IRF510 directly above that circuit block. If you look closely you will see the cutout in the board where the there is access to the heatsink.

 

 

 

The above board is the blank board hot off the CNC Mill. Additional work involved the removal of material where the IRF510 will penetrate the board. That was done on my manual mill --yes I have two of them. The heat sink is mounted to the PC Board and electrically connected so that it is actually a shield. 

 

The above photo show how the Si5351 is affixed to the board and was taken prior to the installation of the Driver and Final stages.

 

I will take some additional photos as the construction progress. I am still noodling the front panel as I need to pay attention to the "ergonomics" of how the controls are arranged. Keep in mind that panel size will be 4.375 inches wide and 3 inches high. That is about 13 square inches and that must accommodate two large real estate items -- the large tuning knob and the display.

 

A question was asked about V1.0 and V2.0 and a comparison of their performance. I was delighted to see that both perform well and are essentially equal. The V2.0 in reality makes the rig be a compact package.

.

Stay tuned!

 

73's

Pete N6QW

 

11/04/2017 ~ Simpleceiver Plus V2.0 First Transmitter Test . Take note a 2nd video was added to document the improved receiver performance with the one capacitor change  (10NF) to the Drain on the 2nd IF Amp stage

We started of the day by building a surface mount version of our Microphone amp circuit that was originally developed for the LBS II transceiver.

The squares I milled out were 0.15 X 0.15 inches and the assembly is as shown above. Noteworthy this was designed over two years ago. This really works well!

Thus after building the microphone amp I hooked everything up and the output was low and the sound was garbled. Well if you look at the photo above -- there is a wire going from the 10 K surface mount resistor to ground as the SMD resistor straddles two squares. If you forget to include that wire then you get low output and garbled speech. I also found that by taking the output off of the drain of the of the second J310 Combo versus the junction of the 68 and 470 PF caps --more output and the instability issue I noted in the earlier video was in part from too low of a battery voltage. No instability with a higher voltage and the 10 nF connected to the drain.

You can see the transmitter testing here.

 

 

 

 

About another week and we should have board #2 completed ready for air testing.

 

73's

Pete N6QW

11/03/2017 ~ Simpleceiver Plus V2.0 Inhaling RF.

Today was a great day as we got the receiver portion inhaling RF. I will do a bit more of peaking and tweaking and then build the microphone amplifier to test out the transmit function. We are about a week away from having a complete 2nd transceiver.

73's
Pete N6QW

11/02/2017 ~ More Progress Photos and Notes

As of 1600 Today!

This afternoon I finished off the Audio Amp stage. The Finger Test (no not that one) produced a loud hiss on the output --thus this stage is working. Tomorrow's work plan is to add the two cables for the LO and BFO and with an outboard 2N3904 RF amp I will see if the receiver circuitry is working.

 

I also must modify the Arduino sketch for the 9.0 MHz IF but that is but a 5 minute effort.

 

Following that series of tests will be the building of the single transistor (2N3904) microphone amp stage that will reside in the island square area of the lower left hand corner. Virtually all of the power wiring and the controls for the audio amp and audio output plus the microphone input will be run underneath the PC Board. This sure makes things a lot neater.

 

The steps after that is to cut the top board for the RF circuits, TR & Control Relays and the LPF.

 

Still noodling the Front and Rear Panel layouts  but the color scheme will be Juliano Blue.

 

BTW I have seen some CNC Mills advertised for sale that can be had for about $300. Since I have most of the circuit board patterns stuffed in the computer cutting new boards is a short piece of work. Christmas is coming --Time to either give yourself a present or to share with your family your Christmas Wish List.

 

On a sad note, once again I know that as usual this year my XYL will get me another SUV present (Socks, Underwear and Vitamins).

73's
Pete N6QW
**********************************************************************************
Today I added to the wiring and a couple of notes about impedance matching. The GQRP Filter has a Z in/out of 500 Ohms and so we will need to match that impedance of the two stages. On the output side of the 1st stage we have a 2 dB pad with an output of 50 Ohms --so a match from 50 to 500 Ohms is a 10:1 match. This easily done with a 6 Turn and 19 Turn transformer wound on a FT-37-43 Core. 6^2 = 36 and 19^2 = 361 ----361/36 = 10:1. Thank You Mr.Boyer.

On the input side of the 2nd stage we have 2.2K and so we must match 500 to 2.2K or a 4.4:1 match. This again is easily done with a 9 Turn Primary (500 Ohm side) and a 19 Turn Secondary (2.2K side) Thus 9^2 = 81 and 19^2 = 361 . 361/81 = 4.45 : 1. Thank You again Mr. Boyer.

 

 

 

 

Noteworthy is that I used some 1/4 inch aluminum pillars to elevate the board above the base plate and made penetrations through the PC Board so the wiring would pass underneath the board. Look closely and you will see the two SPDT relays that are used for routing the signal through the IF Amplifier block for Transmit and Receive which was successfully demonstrated in the V.1 Prototype.

 

I also used my standard color code for wiring.

 

• Red wires for circuits powered at all times --IF Amplifier block
• Orange wires for those circuits powered only on receive -- Audio Amplifier
• Yellow wires for circuit powered only on transmit --Mic Amp, Relays and Transmit chain
• Black wires for grounds

That is it for now -- if I get a chance to add the parts for the audio amplifier we may get to test this on receive later today.

73's
Pete N6QW

So OK many of our builders are still in the process of collecting parts for the Direct Conversion Receiver version (that was three configurations ago). But just in case you are ready for the next (and final) iteration of this project here we go.

 

Version 2 -- What is it? V2.0 is the Simpleceiver Plus SSB Transceiver Architecture with the following changes:

 

• A GRQP Club 9.0 MHz Crystal Filter is used in place of the homebrew 12.096 Four Pole Filter. This gives the advantage of acquiring the matching crystals for the BFO and with a 5 MHz Analog VFO you can have a two band rig (20 meters or 80 Meters). The only change required is the appropriate matching Band Pass and Low Pass Filters. A couple of relays and a toggle switch will put you on either band. So a big plus here. Or you can leave it on 40 Meters.
• Compacting the rig in physical size. I have used two 4 X 6 inch PC Board and fit all of the circuitry on these two boards which will then be stacked upon each other. The main board has the Band Pass Filter, the RxTx mixer (ADE-1), the IF block module comprised of two amps and the filter with the relay switching network, the ADE-1 Product Detector/Balanced Modulator, the Microphone Amplifier and the Audio Amplifier. 
• The upper (second) board will have the RxTx RF Amplifier, the driver stage and the IRF 510 Final, Low Pass filter and the TR relay switching scheme.
• The Si5351/Arduino/Display will be mounted to the front panel.
• The finished size should be about 4.5 Inches wide, about 9 inches deep and about 3 inches high. This is not a miniature rig but certainly small and will be painted Oasis Blue

Here are some photos of the work in progress: The grid in the lower left hand corner is for the Microphone Amp and the grid in the lower middle is for the Audio Amplifier. There are some blank spaces on the board where the switching relay will be installed

 

 

 

73's

Pete N6QW