Monday, December 5, 2016

FPM5 -- Coming Down the Homestretch!

FPM5 ~ The Final Assembly is on the Threshold!


December 5, 2016

Some really good news -- thanks in large measure to the efforts of Greg, VK1VXG, I now have the capability of when you move the band switch to a new band the new band starting frequency will display. Thanks to all who emailed me and made various suggestions --your efforts are very much appreciated. So we can now cross that off of the list.
 
Now it is time to get serious about putting the FPM5 into a case. I have noodled what the case should look like at completion and made it large --10 X 13 X 4. The basic metal work was completed today and now it is time to arrange the various circuit boards. My first pass has enlightened me that I will need to make a few adjustments such as placing some of the circuit boards in a vertical position. Realizing this could happen I made the widths of the boards so that they could be installed in a vertical position. In some ways this will also facilitate shielding and will place the boards in a position for maintenance and adjustment. The template was first set with my KWM-4 project.
 
Here is a sneak peek at the enclosure:
 
Front Panel

Front Panel Close Up

Side view of board real estate area

Oblique view of the Front Panel

Fit Check of Circuit Boards. This is a good view of the original FPM300 Mainboard

More Fit Checking




Thanks for riding along --hope to have this done before New Years.
 
73's
Pete N6QW
 

Wednesday, November 30, 2016

A Little Arduino Magic for the FPM5

Adding some Arduino Functionality ~ FPM5

12/03/2016 ~ Update of Progress on the FPM5



I should start by saying that I have been receiving a lot of world wide input on my "clunky" solution to changing bands and having the display read correctly. In quick review my "clunky" approach was to move the band switch to the band of choice and then hit a momentary Push Button and Shazam! the display would read correctly and as a bonus the correct filters would be selected. The inputs received were in the "bowling lane" of simply move the band switch and the display will read correctly. I used the term bowling lane to reflect a large path of approaches versus a narrow line.
 
Some suggestions worked, others didn't and some worked better than others. The root cause is that I am using then analog pins for the band switch input. As the Oracle of Italy and one of the founders of the Arduino project, Massimo Banzi stated in his tutorial "you could read the random noise on one of the analog pins and use that for a random number generator" and that my friend is without anything even connected to the pin. So a lot can happen and does! Several early suggestions were to use either the internal software pull up (Arduino 1.0.1 or later) or to physically install pull up resistors. By doing this there is 5 volts on the pins and random noise is ignored. Thus to activate the band the pin is pulled low to ground through the switch contact again no random noise. Thus the analog pin is at 5 volts or ground and nothing in between!
 
In reality nothing to date works as well as my clunky solution; but I am sure with more effort the software solutions will prevail. This is where my lack of software genes, advanced age and frankly not knowing anything has come home to roost. But I do thank all who have given me input --BTW I have picked up a few new tricks that will prove helpful in other things I will do.
 
Oh in tripping through the options you can have for this blog --after over a year I found out you can actually search my blog inputs --so look for the search box. I did try it and found it works. But hey what do I know. The comment from Sgt. Schultz in the TV Comedy, Hogan's Heroes: "I don't know nothing" is well applied to me personally!
 
73's
Pete N6QW 

12/02/2016 ~ More 75M contacts, Software Fixes and Front Panel work.

Today had a couple of more 75M contacts and this time we made the 400 mile hop to Sacramento running 100 watts and got an excellent signal strength and audio report. The 20 Meter output has increased but is still only about 40 watts. I do notice a tendency for oscillation if you crank the power higher on 20 Meters --so my haywire, ground loop, poor shielding resulting from the "al fresco" layout will be further evaluated once I move to the box and have better grounds, shorter wires and shielding.
 
Today I installed the Arduino/Si5351 literally on the front panel. The TFT uses four mounting holes. Instead of a nut on the four screws I installed a 3/4 aluminum 4-40 pillar. I then made a vertical sub-chassis that was just slightly larger than the prototype board I am using for the Arduino/Si5351. So the drill is that the Arduino/Si5351 will be mounted on the vertical chassis which in turn picks up the 4 mounting pillars holding the TFT color display in place. This conserves space and makes this more compact. Once again I used right angle SMA connectors off of the Si5351 board.
 
Rear view of the front panel and the Arduino/Si5351 board.


73's
Pete N6QW
 
 
12/01/2016 ~ News Flash -- 1st contact on 75 Meters
I still have the crude 3 position "bandswitch" (two DPDT toggle switches) which controls the BPF and LPF banks  and for the most part have only listened on 75 and 20M. All of the QSO's so far (well over 200) have been on 40 Meters.
 
So here in the 12th month I thought I would try a contact on 75M. It works! Today I had a nice 15 Minute chat with Bill, K6GZ located in Hesperia, CA and now confirmed that the FPM 5 is air worthy on 75M.
 
Some initial tests into a dummy load on 20M have been less than satisfactory as the output is really low--like less than 200 MW. I will be chasing that down and possible problems are I goofed on the BPF and LPF calculations or some of the earlier amplifier stages tend to favor the lower frequencies. If all worked the first time then there would be no fun, no hair pulling and no drinking!
 
Greg VK1VXG in response to my post of yesterday has scratched out a solution to the band switching that involves less hardware, really simple programming and consists mainly of dropping the water level versus building a completely new higher bridge. Thanks Greg! Now I have some more Arduino work to challenge my feeble brain.
 
73's
Pete N6QW
 
11/30/2016

For those who have just joined us, the project currently on the workbench is taking the mainboard out of a 1970's hallicrafters FPM300 and building a whole new transceiver around that board. The original 1970's FPM300 was a hybrid radio using tubes in the driver and final stages. For my project I have added the Si5351 for the frequency generation and carrier oscillator and along the way added a 128 X 160 color display. The rig is designed for QRP operation at 5 watts but can be configured to run 700 watts out. The rig is now working on three bands and soon the other two bands will be added. At completion it will operate on 80, 40, 20, 15 and 10 meters just like the original FPM300.
 
Putting the new rig on multiple bands was to be done using a conventional 5 position panel mounted switch. Sure I could have used a keypad and simply punched a key and the rig would have been on a new band. A year ago I did that with a Ten Tec Model 150 which formerly was a crystal controlled commercial transceiver. But this time I wanted to have a rotary selector switch to select the proper Band Pass and Low Pass filters. Besides this gave me a chance to learn to make circular dial plates on my CNC mill. BTW that adventure did take several tries before I figured out the indexing was 30 degrees and not 36 degrees! The band pass and low pass filter elements use a common buss with pairs of relays at each end of the networks. Then by applying power the correct sets of BPF's and LPF's are put in line on the band you want to work.
 
The following photos show the dial plate, the rig "al fresco" operating only on 40M and the third photo the addition of the BPF and LPF boards which now has it operating on 80, 40 and 20 Meters. I was having a problem with the 20M band --the rig was deaf. I thought perhaps I had a problem with the 42IF123 IF transformers that were modified to work on 20 Meters and so now the 42IF123 transformer style BPF has been replaced with a discrete component BPF that was first simulated in LT Spice. BUT that still didn't fix the deaf problem. Then I discovered that I had not soldered the ground pin on one of the two 20M LPF relays to the ground plane. So no signal was being switched into the 20 Meter LPF from the antenna buss. A quick dab of solder and peaking of the BPF and it now is working on 20M. A check of my work after I soldered in the parts would have found that problem early on. I just got in a hurry.
 
Dial Plate
 
Cool Blue Front Panel
 
Relay selected Band Pass and Low Pass Filters
 
 

The Arduino Magic!

The initial thoughts on how the band switching  would work was to set the LO range on the Si5351 from 160 to 10 Meters in one continuous band. If I was say on 40 Meters, and wanted to QSY to 20 Meters I would change the band switch so it would select the 20M sets of filters and then I would place the LO on the 1 MHz step range and crank it from 7 MHz to 14 MHz and then return the step range back to 100 Hz. Now I was on 20 Meters. A few times of doing this and I convinced myself this was all wrong. There had to be a way so when I put the band switch on 20 Meters  going from say 40 Meters that the display would follow and there was no cranking of the encoder! Boom put it on 20 and it was on 20 Meters! [I finally did get awful close to this approach.]
 
This is one of those tasks that looks easy but is really hard. Now I had done this with a keypad -- even on this same board back in 2014; but for this application it was now a band switch. Thus I had to look at how this could be done. Since I am using an Arduino Nano there are 8 analog pins A0 - A7. Well immediately you lose A3 which is the encoder step pin and A5 and A5 which are the I2C pins SDA and SCL which are needed for the Si5351. So this leaves 5 pins, A0 - A2 and A6, A7. Perfect! So now the task was to write code that would detect a high condition on a particular analog pin and then execute code so that a starting frequency for a particular band is loaded into the Si5351. The starting frequencies are as follows: 3.8 MHz, 7.2 MHz, 14.2 MHz, 21.3 MHz and 28.4 MHz.
 
My initial efforts were partially successful in that I could "high" one of the analog pins and indeed the display would follow depending which band was selected and that is where my success stopped. Because of the way I wrote the code and the way I was detecting the high condition I could tune a couple of steps and then the display would reset itself to the starting frequency. No matter what I tried --every time through the loop the Arduino was doing exactly what I stated in the code --it would reset itself to the start up frequency!
 
Now for those seasoned Arduino programmers I can see you snickering and laughing up a storm and saying like the Geico ad "everyone knows you don't do that". Finally I thought of contacting a real resource that has been invaluable in helping me through many an Arduino maze. That person is DuWayne, KV4QB! [BTW check his blog --he has done some amazing work and has a 3D printer -- now that will be a common tool you will find in future ham shacks.] In an email exchange DuWayne said something that was the key that unlocked the door to the solution. He said you have to watch out for noise pulses that may be triggering the circuit. There it was right in front of me! PULSES!!!!!
 
 The Arduino works on a loop principle, where at a specific clock frequency the process involves going through the loop looking for any changes. With my band switch which is a two pole 5 position one set of poles controls the filters and the other pole would apply 5 VDC to the analog pin that corresponded to the band selected. There was the problem -- 5 VDC was being constantly applied to the analog pin! Thus every time through the loop it would reset itself to the table of start up frequencies for each band. So enter DuWayne's comment about noise pulses. The solution was to have a pulse appear, one time, at the analog pin, have that detected, the frequency loaded and the next time through the loop there was no pulse present so the logic would not reset itself to the start up frequency every time through the loop!
 
Finally realizing this was the possible solution I took a jumper wire connected to 5 VDC at one end and the just tapped one of the analog pins and quickly removed the jumper. Boom --the display read the start up frequency and then tuned normally. Thinking back to when I used the keypad --that is exactly what happened --the keypad was a momentary switch and essentially supplied the pulse to switch the LO frequency. So now the answer was to have  a pulse supplied just once, have it detected and then no more pulses.
 
So here is what became the final solution. There were two digital pins available: D6 and D7. Using a panel mounted momentary pushbutton switch connected to D6, engaging that switch generates a pulse which is the output on Pin D7. I experimented with different pulse durations and now have a 50 millisecond pulse appear on Pin D7 when the push button is engaged and connected to Pin D6. The output from D7 is now connected to the second pole on the band switch so that the pulse is routed to and in sync with the PBF's and LPF's
 
 Ok here in the un-elegant solution. I have set the normal startup frequency to 00.000.000. So with the power applied, where ever the band switch is set (or left at the last operation) the appropriate set of Band Pass and Low Pass Filters are selected but until the momentary Push Button is engaged the rig will be dead. A simple tap on the PB will put the display on the proper band. Now lets say you are on 40 Meters and move the band switch to 20M. Now the appropriate BPF and LPF will be engaged but the LO and display will still be on 40 Meters. A quick tap of the PB will move the LO and display to align with the proper filters for the 20 Meter band.
 
KV4QB had some sage advice about noise pulses. Probably thet next iteration will be to rewrite the code so the pins are always high via pull up resistors and that the condition that is detected is a negative pulse (LOW condition). This way, being high all of the time would not cause a triggering by noise pulses.
 
Now it would be nice if this was all automatic -- but I haven't found a clever way of making a single pulse without some sort of manual intervention. I am sure the Arduino illuminati have that answer but it was not apparent to me. Really important here was the journey as I learned a lot about how to do things with the Arduino
 
In passing there are two sub-routines in my code that are associated with changing the LO frequency and the display. The first is the detection phase and the second involves what action is taken once a specific band is detected via the pulsed input. This is a great application of the Arduino "switch" case functionality.
 
Once I get the code cleaned up I will post it on the blog as a notepad document. Oh another of the digital pins, D4 detects when the PTT is initiated and just so you know the display will show:
 
ON THE AIR

 
73's
Pete N6QW
 


Friday, November 25, 2016

FPM5 Band Pass and Low Pass Filter Boards

Failure into Success!!!!

Having a CNC Milling machine in one's garage is a blessing and a curse! I built two new boards after a quick design using G Simple only to discover I made a serious errors on the BPF and LPF boards for the FPM5. On prior similar boards there was a continuous ground plane something which I forgot when I redesigned the two boards and now I had many isolated islands which should have been part of the topside ground plane. The blessing is that you can make boards quickly --the curse you might have to redesign the board.
 
Well enter innovation and my resolution was that I connected the isolated islands to a common ground plane on the bottom side and thus won't have to remake the boards. Today I completed three bands of the BPF and two band on the LPF. These can be seen on the photo below. The 42IF123 transformers do not work too well as a 75M BPF and so this filter was built using discrete components. The filter was 1st simulated in  LT Spice and then built
 
.
The BPF is on the left and the LPF on the right. The screws going down the middle connect the islands to a common ground plane.


This seems to have resolved the problem --when I get it reinstalled we'll find out for sure.

73's
Pete N6QW

Friday, November 11, 2016

Junk Box Rigs ~ The FPM5

Heading into the Final Stretch!

11/20/2016 ~ You Tube Video of a working Analog VFO


 
 
73's
Pete N6QW


11/19/2016 ~ Analog VFO's

Yes Virginia there once was the Analog VFO which today has largely been supplanted by DDS and PLL chips. Bill, N2CQR conducts a monthly podcast (soldersmoke.blogspot.com) where I just ride along and join in on the banter. Bill is a strong proponent of the Analog VFO's while I tend to the PLL and DDS variety. Bill frequently reminds me of our different views almost to the point suggesting that perhaps I forgot how to create such devices. So just in case any one else has a similar view...  I will be posting a youtube video of the VFO in action.

 
 

This VFO uses a high power transmitting cap and tunes a 200 kHz slice at 5.2 MHz --good for use with a 9.0 MHz IF on 20 or 75 Meters.

Pete N6QW

11/18/2016 ~ 1st Mixer and Band Pass Filter Board

In preparation for the integration into the case, I designed a combination 1st Mixer [SBL-1] and Band Pass Filter board using 5 bands of my choice. I cut the board on my CNC Mill. Total elapsed time was about 1/2 hour using G Simple for the design and then translation to .dxf files and finally the G Code which is a text file used by the Mach 3 milling software.
 
I placed the SBL-1 on the board so you can see where it will be installed. The five band pass filter will be relay selected using a series of 10 relays, 5 relays each on a common buss. The wiring for the relays will be behind the board which will be installed in a vertical position. This follows a similar board I used in the KWM-4 project which is shown in the 2nd photo. Pretty Cool stuff guys!

FPM5 Mixer and Band Pass Filter Board

 
73's
Pete N6QW

11/17/2016 ~ Slowing down the AGC action.




11/15/2016



Here is the FPM5 with the cool blue front panel.

73's
Pete N6QW

11/14/2016


video


11/12/2016 ~ Latest Video with on air QSO's

 
73's Pete N6QW


11/11/2016 ~ Veterans Day. Let us not forget those who served and are serving our nation today!


We are heading into the final phases of construction as the front panel work sans the painting is almost done.
The FPM5 Front Panel


The layout of the controls on the front panel.


video
 
 
 
73's from Pete N6QW







Tuesday, October 18, 2016

More Junk Box Rigs

 
 
FPM20 Rebirth of the hallicrafters FPM300
 
 
11/09/2016 ~ More progress.
 
 Today I installed a few more controls and am closing in on having the complete front panel in working order.
 
 
 video
 
73's
Pete N6QW
 
 
 
 

 
 
 
11/08/2016 ~ More on the Front Panel
 
 Since we already voted there is no guilt in working on the rig. The Tuning dial has been added and some more video of the rig.
 
 video
 
 video
 
73's Pete N6QW
 


11/07/2016 ~ Building the front panel.

Today I began work on the front panel. With my manual 3 axis mill (yes I have both a manual and 3 axis CNC mill) I made the cut outs for the display and S Meter. There is also a short movie. The final size will be 4 inches high by 10 inches wide by 12 inches deep.
 
FPM 20 Front Panel

video
 
 
 
73's
Pete N6QW
 
 
 
11/5/2016 ~ More work and headed toward an enclosure! 
 
Today I did some work on the power supply board and that is now complete. It seems like the original designer's utilized several unique voltages on the main board such as 12.6 VDC, 3.6 VDC. 12 VDC and 6 VDC. I have a built a power supply board that now outputs these several voltages.
 
I have more or less decided on a box size (large it is) which will be about 4 inches high, 12 inches deep and 8 inches wide. There will be some blue paint involved. For those checking it is slightly less than 1/4 cubic foot in size.
 
I continue to make contacts and since have corrected the LSB BFO by moving it 50 Hz. I now can tune dead on 7.2 MHz and it sounds right!
 
73's
Pete N6QW
 

11/2/2016 ~ The original FPM300

I have received a couple of inquiries wanting to know what did the FPM300 look like as a radio (before I got to it)? Wait no more. The photo below shows it was quite an attractive radio with a top cover that had toggle snaps on the side to enable quick access to the "innards". Once the snaps were released the cover simply rotated over and above the radio. It had a somewhat military appearance. [In the photo look along the lower right hand side of the case and you can see the toggle mechanism.]
 
Too bad it had some problems such as using a rubber band (I exaggerate it was a splined rubber band) for the band switching mechanism to gang control the band switch. Over time the rubber band failed and the band switch became inoperative. The VFO drifted and some of the suggested cures for several of the internal spur problems was the use of aluminum foil to provide shielding.
 
There were several variants such as the last gasp fix called the Mark III. These units tend to be overpriced on the auction sites. Today there are a couple of such listings on eBay and the one below has a buy it now price of nearly $250. If you can find one in a "garage sale" for $5 snap it up.
 
73's
Pete N6QW
 
The FPM300 Mark I

 



 

10/31/2016 ~ Serious DX Action in the CQ World Wide Contest

 
No I am not a contester! BUT contests are a great time to make DX contacts which might not be available on a regular basis. To that end running full power (about 600 watts for the QRP aficionados) I made several Caribbean contacts, three with JA stations and one with a station down in ZL Land. [Keep in mind this was on 40 Meters from Southern California.] Admittedly I got 5X9 reports from all stations; BUT what is telling is that usually I made the contact on the 1st call. No my rig does not have DSP, nor does it have a noise blanker, and there are no funny equalizer  presence settings or dual watch; but it does have a very stable signal and is spot on in frequency. Did mention it does have a color TFT display?
 
What is significant is that the mainboard of the radio was built in the 1960's and after some horse trading cost me about $20. The rest of the hardware came from the junk box and it value is maybe around $50. So here I am with a $70 radio making serious DX contacts using nothing more than a droopy dipole whose center is 26 feet high. Just imagine what I could do with a pair of phased extended double bazooka antennas at 70 feet?
 
Now my mainboard does have speech compression and VOX so it does have a few refinements which I intend to fully explore. So OK cosmetically it now looks like a hunk of junk but in time I hope to run it through the "Juliano Blue" process and make it respectable. So my advice to any one reading this --keep your eyes out for the sow's ear --it just may turn out to be a silk purse.
 
Any one out there have a mainboard from a hallicrafters FPM300 that they would like to have move from their garage or shack? Email me and let me know. BTW there are many radios lurking out there with blown finals that otherwise are functional --you can give those jewels the same treatment and have a reborn radio.
 
 
73's
Pete N6QW
 
10/28/2016 ~ New Power Amp Stage
 
 I have somewhat changed direction and added a 4 Watt Linear Amplifier Stage which uses a device I found in the junk box --a 2SC2075.  Had a board layout in my computer so about 10 minutes worth of work on the CNC mill and I had a new board. This is shown below. With 4 watts I can drive thru an intermediate amplifier the SB200 to about 600 Watts out. This is a signal that can be heard on 40 Meters all the way to the right coast from the left coast.
 
Schematic ~ the 2SC2075 is substituted for the 2SC2166 with no other circuit changes

 
The "As Built" amplifier ~ The metal case is the heatsink!





Looks like crap works like Hell!
 
 
 
You too can build rigs like this!
 
73's
Pete N6QW
 
 


 
 

 
10/24/2016 ~ More refinements -- improving the power output.
 
Initially I set the carrier oscillator frequencies in the Arduino sketch to the values indicated in the schematics. The USB frequency seemed way off. A quick and dirty test is to set the mode to USB and normally speak into the microphone. The output was much lower than LSB. A second part of the test is to whistle into the microphone (the rig was connected to a dummy load) and the output noted. On LSB the whistle test produced about 1/2 the output on LSB as compared to speaking into the microphone. On USB the whistle test produced about 1/10 the output as compared to the LSB with voice.
 
Using a separate external oscillator for the carrier input I adjusted the BFO frequencies until the whistle test on LSB and USB was at the same power level and these in turn matched the output using speech. These values were much different from the schematic values. But then on closer examination of the circuit schematic for the BFO  both crystals had trimmer plus fixed caps connected across the crystals -- so the actual oscillating frequency was modified in production and different from the marked frequencies. In my rig the BFO is supplied by the Si5351 and the values are set in software. I suspect that I am really close but may be off by about 30 Hz on LSB, which I will further test to verify that hunch. 
 
These changes have resulted in greater output!  I switched the linear amp following the driver stage to the brick liberated from an Atlas 210X. Now I am easily seeing about 50 watts output and driving the SB200 produces about 450 watts on peaks. So we are cooking. This evening I had a QSO with a station in New York where I was running 50 watts and he had a KX3 cranked down to 1 watt. So with a modest power level you can have coast to coast contacts on 40M.
 
I am really excited about this rig! There are some plans in work to make this a two band rig covering 20 and 40 meters.
 
So far I have had about two dozen contacts with stations in California, Washington, Nevada, Utah, New Mexico, Arizona, Texas, Nebraska and New York.
 
73's
Pete N6QW
 
FPM20 now working at 50 watts with an external amplifier!
 
 
 
10/23/2016 ~ The FPM20 is "Alive" and making QSO's
 
The rig went "live" on 10/22 and so far I have made about a dozen contacts. Some of the contacts were made using just the driver stage at 350 Milliwatts (this is the EMRFD variant with a 2N2222 and BD139). Several were made using the outboard SS amp running about 25 watts. One piece of DX was a QSO with a station in Nebraska. (KD7YUW) where I was running 25 watts.
 
This is how it looks but I desperately need to tidy things up.
 
This is the rig "as is" as of 10/23

 
 
This is the 350 MW driver stage and low pass filter.


73's
Pete N6QW



 
 
10/19/2016

Building a Junk Box Rig from a Commercial Transceiver Board.


In the photo below is a "breadboard" version of the FPM20. Essentially the heart of this rig is the main board from a hallicrafters FPM300 SSB/CW transceiver and the S Meter. I have added a 2N3904 Receiver RF amp stage, a band pass filter comprised of two 42IF123 10.7 MHz IF transformers padded to 7.0 MHz, a Si53551 providing the LO and BFO signals and a power supply board (the FPM used weird voltgaes0. Rounding this out is the SBL-1 that acts as a receive and transmit mixer stage. The audio output stage uses an LM-386-3.
 
In the video above the receiver was working but I got no output on transmit -- that is until I realized on the output chain (the final device on the board) consisted of a 40841 Dual Gate MOSFET. that has ALC applied to Gate 2. Upon close examination of another of the circuit diagrams I saw a note about ALC. On receive the voltage is "0" but on transmit with no signal applied the voltage was 6 volts supplied from the ALC circuit -- this was a negative ALC. As more signal (such as from over driving) is developed the ALC becomes less. I had applied no voltage to Pin 17 on the board so essentially the circuit was cut-off! I added a 5 volt regulator to Pin 17 on transmit and the circuit now works on transmit --and CW. The FPM 300 used a keyed tone for CW generation.
 
A new board will be built using my standard 2N3904 bi-directional circuit which acts as the RF amp on receive and the transmit pre-driver on transmit. There is sufficient output from the 2N3904 to fully drive the 20 Watt brick sold by CCI. This is why the rig is dubbed the FPM20. We are on our way.



73's
Pete N6QW

Saturday, October 8, 2016

That's All Folks!

This is the latest and last posting on this blog. There will be no further blog entries!

Keep on melting solder.

73's
Pete N6QW