February 27, 2024. Just Say NO!

No is such a powerful answer! Like when your 12-year-old daughter wants a butterfly tattoo on her back -- 10X full size!

Vintage 1967 FTdx100

So, it is with our hobby that we should say NO. We ought to narrow that NO a bit as we are not talking about an ARRL membership or whether to outlaw LC VFO's or take up contesting or even buying an ICOM IC-7300. 

The NO is for me personally and that involves buying any Boat Anchors or even gear that is older than 25 years. 

Hallicrafters SR-150

[For those looking for schematics for a simple project or code for the Seeed Xiao RP2040 we will not be covering that today so you can close out this posting.]

Just look at the front panel of the SR-150 as it literally says take me home to your ham shack. It has large knobs for those of us with Fat Finger Syndrome that we can actually twiddle! The panel layout forces you to look at the dial scale and S Meter. 

The SR-150 production run was during the early 1960's and just the radio alone was $650. It had 19 tubes and known for its quiet receiver. As a newly commissioned Ensign in 1963 my pay was $222.50 per month. If I could amass three months of gross pay, I could buy one. So, while the SR-150 was at the top of my list the Collins KWM-2 was completely off the table.

Fast forward to the late 1990's when I was retired and the kids were out of college so there was a bit more money in the radio budget, it was time to fulfill some dreams of past times.

Yes, it was not an either or, but I bought both the SR-150 and the KWM-2. That is when I realized the technology time warp continuum. What was leading edge in 1963 was now very far behind what was being sold in the late 1990's. One of those two got moved on but I still have the KWM-2. 

Now with no time to build I still look at eBay and see those rigs of old. I keep saying NO! So, if you have an itch to buy a radio older than 25 years, don't as there are some hidden land mines awaiting your stepping off the plunger.

The SR-150 as nice as it looks had a non-linear VFO dial. C'mon guys for $650 it should be linear. 

A neat feature today for the SR-150 as it used 12DQ6 tubes in the final is that you could buy a set of matched 6DQ6 tubes for about $25. A simple filament string rewiring enables the use of the 6DQ6. 

But this is a 1st part of the critical NO. Many of the offshore rigs had final tubes that are near impossible to find, and no matched sets. The Yaesu FT-101 series comes to mind. There were also driver tubes used where American brands won't work (12BY7).

Most of the electronic parts are easily found except for things like encoders. The ICOM IC-701 was the 1st solid state rig I ever saw. It was so small and wow frequency stable and a linear VFO. It had a lot of relays to switch in BPF's and LPF's. (This was late 1970's a mere 15 years past the SR-150). 

I was gifted an ICOM IC-735 that needed some repair and the tech shared with me that they no longer serviced the older ICOM radios like the IC-701 as they could not get the encoders which was kind of unique in the mid-70's and that those little relays were unobtanium. That draws us to the radios built before 2000 and the custom parts that are only found in donor radios. That forces the buy a pair as one is a spare.

Mechanical parts are particularly hard to find. I have three working Collins KWM-1's. It might surprise you to know that while the KWM-1 has a PTO it has a friction drive mechanism that uses an idler wheel that drives the outside of the circular dial. The idler is two circular plates that have a flanged outer circumference and the dial fits between those two plates thus creating a captive friction drive mechanism. 

There is no way to adjust the resistance of that arrangement. I have a SWAN SW120 with the same arrangement but the SW-120 has a curved washer in the mix that enables you to set the feel to very loose or tight as you tune. 

One of the KWM-1's has the idler that was physically pinched by a prior owner and so the tuning is not smooth. I have an idler from a 4th donor KWM-1 and it is corroded and not usable. I have not been successful in locating that part.

Custom IC's are another huge negative for older solid-state radios. With a shift to microprocessor's as embedded elements some were custom and not COTS (commercial off the shelf) so when you read on eBay: Powers on, but LEDs show 9999999 think the microprocessor is toast. Say NO!

Other red flags are like when you look at the schematic for the LC VFO's in the older boat anchors you see a capacitor with no value but a note "factory select". How lucky do you have to be to have such a factory select capacitor in your junk box?

Crystal and Mechanical Filters are another significant problem area. The manual for the KWM-1 tells you that the 455 kHz filter and the BFO crystal are factory select. You are told if you change the filter, you must change the BFO crystal. There is no netting capability in the BFO circuit. The SR-150 uses a 1650 kHz Crystal Filter and I am not aware of any other radio that uses that IF frequency.

Relays are also an issue. The KWM-1 uses three odd ball relays -- ruin one of those and you might as well junk the unit. 

Many radios were built in such a way that servicing is a huge issue. I had an NCX-5 Transceiver that while it was mostly tubes had a solid-state VFO with plug in transistors. The VFO board was under the main tuning capacitor and there was no way to remove the 2N706 from its socket without a major disassembly. 

The same for an early Yaesu FTdx100. The power supply electrolytic cap terminals were inaccessible underneath the factory wiring. Replacing those caps was a major effort. No thought was given that the radios might need to be serviced. 

Another issue with the vintage 1967 FTdx100 is that some circuits are installed in soldered shut metal boxes. Check my website https://www.jessystems.com for a look at a refurb I did on a FTdx100. I only paid $35 for it so it was a bargain.  

When I moved back to California in 2013 this particular unit was passed on to another ham. Exactly 2 years ago I found another FTdx100 in much better condition for not a lot of money. That unit is shown in the front-end video.

In 1967 the FTdx100 was a sort of a test market transceiver and not really actively marketed in the USA. It has Germanium transistors and three tubes. Luckily the 6JM6 finals are easily found in matched sets and the cost is low.    

The follow-on radio from this test radio was the FT-101 and I thought I heard that somewhere north if 250,000 radios were sold world-wide. Even today an unmolested FT-101 commands a hefty price north of $300. The finals are 6JS6C's and they are costly, hard to find NIB and as matched sets. Some daring souls have converted their rigs to 6146's.

I could go on and on but a final word about the low-end radios sold during 1960 to 1990. They were low end because of value engineering. The manufacturers reasoned hams being hams had a product life cycle of about 1 year to 18 months before they had the itch to buy a new radio. As long as they could find the cheapest part that would last 18 months, it was selected for the build. Mechanical switches and relays are the issue as well as electrolytic capacitors. These are failure points in the old boat anchors. 

Cost is another issue. The old radios are commanding prices off the scale and do not represent a true value. How about a Central Electronics 100V that has issues for $999. It likely will get bought.

I leave you with a final caution to me --- NO!

Think build it or buy new!

73's

Pete N6QW

February 26, 2024. A Simple Arduino SSB Transceiver Sketch.

 

Seeed Xiao RP2040 Digital LO/BFO 2/26/2024

In my email this morning was that very question concerning my providing to the sender a simple Arduino SSB Sketch. This is a landmine underfoot just waiting for me to step off the plunger.

The very way the question is stated suggests the sender is looking for a quick fix and likely lacks a rudimentary knowledge of the Arduino. Fact one there are no simple SSB sketches! 

His question is better characterized as a no-frills version to one you would find on Rodeo Drive in Beverly Hills. No Frills = one band, 16X2 LCD, no VFO memory, no S Meter, no Tune Tone or Splash Screen. The Beverly Hills version would have all of those features less the LCD but sports a 3.5 Inch Color TFT Touch screen to boot. 

That said about 80 to 90% of both sketches would have common elements. These common statements include identifying libraries, and which display type. Other statements would identify pins that would be used and various statements identifying the startup frequencies, BFO frequencies, and lest I forget which pins are the Encoder Pins. 

The Setup Section of the sketch would do just that by setting up the Si5351 (PLL and the clocks for LO and BFO) and setting the Pin Mode (which pin and whether an OUTPUT or INPUT). 

Then comes the Loop section where everything in the loop is where the actionable items are included such as has the frequency changed, have you called for a USB/LSB change or have you put the rig in a Tune Mode and things like using the 2nd VFO or changing bands?

A real learning experience similar to setting up directories on your computer to collect stuff versus loading everything as individual files on the C Drive is to keep the Loop to a minimum. Simple statements in the Loop such as Checksideband(); with a separate call program void Checksideband() {} has the change of sideband being checked without cluttering the main loop with that action. Another would be CheckTune(); to see if you placed the rig in the Tune Mode. Still another would be CheckCoffeePot(); is it still hot. 

I have not responded as yet to the email as I foresee a huge time sink (my time is limited) when he gets the sketch and then the problems start. Several years ago, I supplied a sketch for a similar request. That individual had little knowledge of Arduino and made significant changes to the supplied code. When that didn't work, he sent his code to me and literally said fix this. He got irate when I wouldn't fix it. 

My advice is to spend about $15 and get Banzi's book Getting started with Arduino and perform every little program in the book and then look to simple SSB sketches. ARRL has some publications as does W8TEE, Jack Purdum. One of my most complex, entirely built by me program was the LDMOS amp controller. All of that extensive programming started with examples in Banzi's book.

In giving about a second's worth of thought to the email perhaps the answer is in the 1st photo which took the Seeed Xiao RP2040 from the prototype board to a wired assembly. The code is minimalist and about the only thing it will do is tune the frequencies and change the sideband. The display is a 16x2 and there is a step tuning adjustment on the encoder. It is a single band 20M. 

In the same path, yesterday I received an email about limiting the tuning range to just the ham bands. In many of my sketches there is code to do that where a minimum and maximum value for the LO can be set. I typically say 2 to 30 MHz. Thus, most of my code will boot up to a specific band but can tune way above and below that band. The request came from offshore as evidently it was a legal issue in that country that you could only have ham radios that tune the ham bands. 

In my response back I showed the lines of code in the sketch and to use these two values versus what was in the code: 14002000L and 14348000L. This simply says no lower than 14.002 MHz or no higher than 14.348 Mhz. You can crank the encoder all day long, but the LO will be frequency limited. The email back to me -- I don't understand. Big clue -- he has no clue!

So there are no get Arduino quick schemes and if you abhor reading and learning, friend you are SOL!

73's

Pete N6QW

February 25, 2024. Homebrew rigs can sound excellent.

Gotta ask? Does your homebrew rig sound this good? The 2.7KHz wide filter brings a bit of extra presence to the sound. Indeed, you would expect no less from two 90 Derees Out of Phase Direct Conversion Receivers.

I am having a bit of fun with this rig, as I purposely have set the Si5351, so it is about 20 Hertz low. This is so I can drive the FLEX and Apache SDR Police bonkers as they tell me I am 20 Hz low. I then will say that is to give you something to do besides tout your expensive radios! This is the original prototype based on ZL2CTM's work that has undergone some repairs and a tune up.

Interesting how I calibrate the Si5351. I have a Hermes Lite2 SDR which is superb and rivals some of those boxes costing $3 to 4K. [At about 10% 0f the cost.] Step one is to sync the HL2 to WWV and have those two signals' dead nuts on. Then I bring a lead from the HL2 antenna port near the divide by four 74AC74's so it is detecting the LO frequency. I adjust the Teensy 3.5 software until the detection of the signal, the HL2 and the 40MSDR are all on the same frequency. 

Changes I made to the original work of ZL2CTM is to add modem transformers to the Line In / Line Out on the two ADE-1s to abate noise. I also built and installed a new 100 tap point 2.7kHz wide filter using the Iowa Hills software. The Hilbert transform coefficients are not 0 and 90 but +45 and -45 degrees, which of course means 90-degrees.

Some of the construction details can be seen at this website. www.n6qwradiogenius.us

Certainly, you can just go out and buy a Xeigu 6100 for around $500 and it is all band and compact. But you didn't build it!

True also, the "Al Fresco" Helter Skelter look is a put off to some, but it also is a testament to what is possible. Just listen to the signals.

Of note the signals just seem to pop out of a quiet background and the background "noise" is not like I have on other rigs. WYKSYCDS!

73's

Pete N6QW

February 23, 2024. Are You Protected?

Are you protected? This is not about life insurance or about a date with a girl friend. The post for today deals with protecting your circuits and not what you may have been thinking.

Circuit protection is likely the last item on your list or perhaps as often happens not at all. We must strive to be precise and correct for the nit pickers out there so let me bound what I mean by circuit protection.

 

Broadly speaking the circuit protection involves simple things like your wiring when you try to stuff four pounds in a three pound box.  Get a grip, unless you purposefully think about a possible short to the power rail and physically keep wiring away -- IT WILL SHORT! 

 

That was a lesson learned while I was trying to service one of my shirt pocket SSB Transceivers. Similarly think about it when you put the rig in a box -- will there be a short when you screw the top on. Thus, one aspect is the physical hardware.

 

The other broad category is the hardware functionality.  We will start first with reverse polarity protection. Raise your hand if you have never connected a circuit to the wrong polarity. At times you only smoke some of the devices while for other situations there is the giant mushroom cloud over the workspace followed by that awful smell.  

 

We are treading on thin ice here as discussing reverse polarity protection is not unlike the current polar divide between the Democrats and the Republicans. There is an array of solutions for RPP (Reverse Polarity Protection). They range from polarized plugs that only mate with your power supplies to included circuitry to prevent that possibility.

 

Many hams simply use a power diode in series with the Plus lead to the rig. That works but has one small drawback. You will drop 0.6VDC across the diode junction which if operating portable from batteries as the batteries discharge is significant. When your batteries themselves drop to 11VDC -- you are only seeing 10.4VDC at the rig. 

 

I have used the diode with an added twist. The diode feeds the field coil of a small relay. The source voltage is also connected to a set of normally open contacts on the relay. Thus, wrong polarity and the relay does not close and no juice to the rig. This avoids a voltage drop to the rig caused by the diode BUT does add to the current draw on the batteries. With a bit of searching, you can find small relays whose contacts will handle 2 or 3 amps and their field coil has a low draw. Others might suggest the use of polarized relays thus no diode needed.

I first used this circuit on a project to take the Hallicrafters FPM 300 and rework it to be solid state. (Yeah, I do weird things like that)

Re-birthed FPM300

It was near midnight and RPP was on the list as the last item. Thus, the idea sprang from what I grabbed from the junque box at that time of night. I got several emails about my archaic solution and why wasn't I using a PFET power switch and on and on. Look it was midnight, even Amazon couldn't get me something quicker and it works!

Another piece of protection is to add a fuse, and this is for protecting your finals. In days of old many linear amplifier circuits included fold back current protection. Without this protection and especially on bands like 75/80 meters where having a High SWR will cause an excessive current draw and you could melt the RF devices. 

I had a uBitx V3 and when I first got it, I saw there was no fold back protection and that a simple in line fuse set at the right value could save those finals. Now the right value is a high enough amperage, so you don't have nuisance tripping but low enough if you draw more than normal current -- she blows. 

 

I posted my suggestion on the bitx20 reflector where I received a startling comment. The commenter said he read on the Internet that the IRF510 was "bullet proof" and why was wasting their space and time about including a fuse. This lurker must be an Illuminati. I put the fuse in at the get go and sure enough on 75Meters I blew the fuse and not the rig.

Another protective circuit which can be external is the CROWBAR. This has seemed to have lost its popularity but was a staple in many of the Ten Tec Supplies like the Model 262. Essentially the crowbar is a voltage sensing circuit between the supply and your rig. In that circuit is a SCR and a Zener reference diode. As long as the supply voltage is less than the firing point of the SCR -- all is well. The microsecond that the source voltage hits the firing point the SCR goes to ground and the fuse blows. While most solid-state circuits sourced as 12 or 13.8VDC usually will do OK to about 15VDC - after that you have successfully completed a production of smoke test. ZD1 sets the firing point in this case 9.1VDC. For a Ham supply, 14.5VDC would be a good choice.

 

 

If the new hardware you are working with has a significant investment in parts, then RPP, a Fuse and a Crowbar are cheap protection. These three approaches however will not provide any protection with the girl friend! It is always a case of the right tool for a proper job!

 

So, it has been a boring trip but there just might be some piece in there to protect your rig that you just built. 

 

73's

Pete N6QW

February 22, 2024. I get mail!

I get lots of emails including an exciting notification that $282,567.19 has been deposited for me in a Bank located in Nigeria.

Often the emails may involve questions about my published projects or perhaps a comment on a You Tube video. Some were referred to me by others. Mail is good and a distraction from my day job at the Board and Care Facility.

That said there should be a bit of effort on the part of the sender to frame the question so it can be answered. One email simply said "Send Me the Code". So OK the code to my Junior HS padlock was 38 22 34. It took two more rounds to get to which code he wanted.

Just in the last week came two emails requesting technical information with one specifically on how to address a noise problem in a radio. This noise issue was something I ran into personally and found a couple of miracle cures. I was happy to respond to that inquiry for it was a real world problem for me.  

This power conditioner circuit came from Bill, N2CQR and solved a problem I had with this beautiful color OLED that had  a switching power supply installed on the back of the display. The switching noise was being picked up through the power rail to the LM386

Follow the two yellow wires!

The other suggestion was to purchase an inline ground isolation device (Amazon ~ $8)

MPOW In Line Ground Isolation Device

It takes time to respond to these emails and I heard nothing back from this sender. A courteous reply like Thank You or I got it would seem appropriate.

Then there is the separate category of what I call the Snarky comments from some Home Brewer's who think homebrew is just like building a kit. These are real comments from real senders.

Some of the comments are actually all in one. A ham was building the P3ST direct from my design. He should have waited for K7TFC's kits to be available. 

 

His issue was the Band Pass Filter. Since he didn't know where or how to find the correct part specified, he substituted a smaller value than what was required for the section coupling capacitor. 

 

He measured the response with his newly acquired Nano VNA and saw a peaked curve which is indicative of too small of a coupling cap.  His email to me "My Nano VNA says there is a problem with your design."

 

My email back -- check the section coupling cap it is the wrong value. His email back where do I get those small value caps. I gave him three answers including a twisted wire gimmick.

His email back -- I never built a gimmick but it won't work as the wires are too floppy. K7TFC's kit part for the BPF section coupling cap is a twisted wire gimmick. 

The real thrust is this person was unprepared to take on a project like the P3ST sans any getting smarts about the circuits and worst ever -- he was not listening but wanted to simply say your design sucks!

We all need to do a better job of listening and be responsible in our answers. If you don't know say so. I marvel at these .io groups where a question is posed and an answer is given by one of the resident "lurkers". Typically it is answer that could cause damage to a radio or is solving a different problem. 

 

WE like to think we know everything but we don't. In a recent solder smoke podcast I mentioned the use of Lissajous Figures to display a 90 degree phase shift. Bill asked me what was the correct pronunciation of that word. I admitted I didn't know.  I just say "Lisa Juice". To me the correct speak is not as important that if I see an ellipse in the right hand upper quadrant that it is not 90 degrees. 

73's

Pete N6QW

February 21, 2024. The impact of technology!

Charming Radios of Old! Or just plain old and no charm!

Looks Like an AMECO AC-1 Clone

AMECO AC-1

My build of the W7ZOI Dec89/Jan90 QST, 20M SSB Transceiver 

 

Imagine making contacts with the CW transmitter in the 1st photo. The wiring for the Key is 300 Ohm Twin lead. Like we used to say when I was in the Navy, any port in the storm. BTW an AMECO Clone Kit today is several hundred dollars.

The 3rd photo is a rig I still have. W7ZOI had a hand made dial readout --- mine has an LCD with the EI9GQ VFO stabilizer. The advantage of technology and a 10–15-year span between the two builds., Same design with some updates.

 

In thinking about this post, I reasoned that technology advancements have two subsets those being cosmetic and functionality. 

Despite the handwritten dial scale, (4th photo) on the W7ZOI original that in no way reflects how the rig performs and how it sounds on the air. Of note W7ZOI's tuning system has a Coarse and Fine tune controls. It likely won't get you to a 20Hz readout but certainly a lot closer than with just the coarse tuning. 

W7ZOI did something clever things in this radio (well actually lots of clever things) with the output side of the VFO. He installed a low pass filter following the 5 MHz VFO (9MHZ IF). This is a way to reduce VFO 2nd Harmonics and spurs. 

Most likely if LCDs in 1989 were low in cost, there would be one in the rig. Then again, adding more than a hand write on the case would involve significant hardware and possibilities for internally generated noise. 

My LCD install was a by-product of solving the dreaded VFO frequency drift issue. The VFO in my rig was built in an aluminum box that had 1/4-inch walls. All the holes were tapped for 4-40 screws. The internal drive was a Jackson Brothers which was then gear driven with anti-backlash gears on the outside. 

The inductor was an Air-Dux coil mounted on isolation pads and glued to a chunk of plexiglass. Multiple NPO and Silver Mica caps were used in the tank circuit and power was fed using a ceramic feed through cap. The variable cap came from England and was a double bearing type. Yet it drifted!

It was about this time I learned of the work of Ed, EI9GQ with the PIC 16F84 micro-controllers to stabilize the frequency. Essentially, once engaged as you QSY the frequency is read and stored. Through the loop each time the frequency read is compared to the frequency stored and any deviation causes a +/- correction voltage to a small diode which then changes its capacitance, and you are huffing and puffing the frequency back to the stored value. Change frequencies and the process is repeated.

Thusly my version gets the advantage of the cosmetic look and the stay put on frequency functionality. It was a twofer. I got the stabilized frequency and a digital read out came along for the ride. My 1st Bitx 20 had the same LCD and Frequency Stabilizer hardware.

Back to photo #1. I never had an AMECO AC-1 and I don't think I ever cloned one. But for a ham just starting out this would be a great 1st rig as you have to work to make contacts. Thus, each contact, was an adventure in itself. Just thinking, imagine sitting in front of a BC-455 (40M ARC-5 Rx) with this transmitter and making CW contacts on 40M. It might be fun for at least a couple of hours.

73's

Pete N6QW