Wednesday, July 25, 2018

2018 ~ The Year Of SSB Transceivers

7/29/2018 ~ Arduino Code for LCD to OLED replacement http://www.n6qw.com

Look inside the Purple framed text for the link to the code. You will also have to have the included files -- see the notes in the sketch and as mentioned below. If you are unsure on how to do this … don't try it.

73's
Pete N6QW

Secrets Revealed: How to Add a Tune Tone and CW Identifier to your Homebrew Rig. 7/27/2018

Disclaimer: I am not a software programmer nor do I profess to have those skills but I am a person who likes to tinker with things. For several years now I have had a Pulsed Tone TUNE capability with my rigs. I developed the code myself and even figured out how to change the screens to show you are in TUNE. For those who do software on a daily basis --you probably snicker (a lot) at my code. Frankly that is unimportant in that what I developed works!

So today I said to myself "Pete why can't you add a CW identifier following the pulsed tone?" So I did and it works! How this works is that I first put the rig in transmit using the MOX button and then I depress the TUNE momentary push button.

First and all important you need to have a Tone Library in the library section of your main Arduino directory--one that will work with Arduino IDE 1.8.5 -- there is more than one.

There are three lines that must be added initially which state

    #include "Tone.h"
    #define TONE_PIN 6
    #define NOTE_B5  988

Importantly the Tone.h is an included file in the folder and in the sketch that is why it has the quotation marks" ". Next is to identify the output Tone Pin which is Digital Pin 6 and finally Identify the actual tone you want which I chose B5 which is the closest to 1 KHz.

Then we need to identify button states since this is a momentary push button which initiates the Tune process.

   int buttonState = 0;
   int lastButtonState = 0;

We also need to identify the actual Arduino pin that take the Push Button Input to start the Tune Tone process.

  const int SW1 = A2; // provides the TUNE function

Thus we are using Analog Pin A2 to take that input and in the void setup we do that
     pinMode(SW1, INPUT);  // Tune function
     digitalWrite(SW1, HIGH); 

Thus if we put A2 to ground even momentarily it will start the TUNE Sequence.

Now we need to add some subroutines so that instead of writing out the dots and dashes by each element that makes each timed element for a dot space, dash space we can simply call up a dot with all of the proper timing for turning on the tone and turning off the tone. Ditto for the dash whose timing is 3 times as long. So now with the subroutines we can just call up a dash or call up a dot and it will happen automatically. You can even extend this further to writing characters so that you could call up the letters N 6 Q W and it would send those characters. For those who are subscribers to QRP Quarterly you can find a series of article by myself and Ben AI6YR called the CW Sender -- just following our articles! 

Now the delays are set for some slow speed CW which means the newly minted extras who only have to do 5 WPM can read this. Actually it would have been smarter to set up values like: int X = 300; and int Y = 100; and in the delays show it as delay(X); or delay(Y);. This way if you wanted to change the speed you would only need to change two values for X and Y and all else would follow.

//**** Generating CW *********
 void dash(){
       tone(6, NOTE_B5);
        delay(300);
        noTone(6);
        delay(100);
 }
void dot(){
      tone(6, NOTE_B5);
      delay(100);
      noTone(6);
      delay(100);
}


So now we have the dots and dashes and we have the Input pin (A2) and the Output pin ((6) and now for the other subroutine that during the polling of the loop asks have you hit the TUNE button?

void loop() {

       SplashScreen();
       RunOnce = 0;
          
        checkMode(); 
}

So when the loop sees the activation of the Tune Push Button  it shifts to the checkMode() subroutine.

//*********************** See if we are in Tune ***********************************
    void checkMode(){
        buttonState = digitalRead(SW1); // creates a 10 second tuning pulse train 50% duty   cycle and makes TUNE appear on the screen
       if(buttonState != lastButtonState){
        if(buttonState == LOW){
         
        
         
     
          useVFOA(); // Tells what VFO to use for Tune and starts the pulsed tone sequence
        display.setTextColor(WHITE);
        display.setTextSize(2);
        display.setCursor(10,35);   //We are displaying the received Freq of VFO A
               
         display.println(rx1 - bfo);
         display.setCursor(1,50); 
         display.print("TUNE");
        display.display();
        delay(12);
        for(int i = 0; i < 100; i++) {
         tone(6, NOTE_B5);
         delay(50);  // 50 on and 50 off 50% duty cycle
         noTone(6);
         delay(50);
          

         } // This completes the end of the pulsed tone sequence
    
          // The following code sends my call sign at slow speed with a 988 Hz tone. Note
            we are simply calling up dots and dashes. We could take this further to define 
           characters and then this would just say send -- N6QW
          delay(100);   // de N6QW in CW
           dash();   //D
           dot();
           dot();
           delay(300); //E
           dot();
           delay(400);  //A little longer delay between "de" and N6QW
           dash();    //N
           dot();
           delay(300);
           dash();   //6
           dot();
           dot();
           dot();
           dot();
           delay(300);
           dash();  //Q
           dash();
           dot();
           dash();
           delay(300);
           dot();     //W
           dash();
           dash();
           delay(300);
        }
       else{
          //the else resets the screen and puts the rig back into normal operation
        display.setTextSize(2);    // This prints a Black TUNE over the RED TUNE and makes it disappear from the scereen
         display.setTextColor(BLACK);
         display.setCursor(1, 50);
         display.print("TUNE");
   
         noTone(6);
   
       }
         
     
         delay(50);
   
    }
   
   
 That is it and you too can add a CW identifier to your own homebrew rig. Keep on tinkering.!

Pete N6QW




At Times a New Solution > A Fix!

For those not used to mathematical notation the title reads that a new solution at times is greater than fixing the old problem. So it is with a recent experience of mine and I offer this to those who perhaps have had similar problems.

Take the Junk Box Rig which was made (in 2017) almost entirely out of boards lying in my junk box. Often I will build two versions of a circuit module with the first being a prototype and the second the finished unit that benefits from the experimenting with the prototype. Or it may be a case of build the first one large and then the second can be shrunk down in size once the prototype is working satisfactorily. Or as in this case some boards were pulled out of working transceivers as the project was no longer used.

Even though they were junk box boards I did attempt to make it nice looking including a cool blue LCD display. So there you go --Juliyellow background with a blue display. The original Arduino code was a lift from AD7C.




For a long time I had resisted upgrading my Arduino IDE to the latest version because I already knew that the older LCD libraries will not play with the latest IDE's. You can even find some fixes from giants like Adafruit Industries on the internet. Most of my earlier work was done in Arduino 1.0.5 and the LCD Libraries I had loved it.

Well several days ago I wanted to make some changes to this rig and attempted to use the fixed libraries with IDE 1.8.5. Well it will display but not all gets displayed. About 15 minutes worth of frustration was my gag level so I said "Lets rip that LCD out of there and use an OLED"!  The code (not AD7C) was extensively modified by me as used on other N6QW projects.

This has some additional benefits as I recently learned how to make two vfos on the Arduino and I also added some features to the rig that would have otherwise compromised the clean looking front panel. 

So six hours worth of work created new code, milled out a new front sub panel, added some wiring changes/controls  and then final checkout.


The two toggle switches to left of the display are for MOX (for you youngsters MOX = Manually Operated Transmit --you won't find that on your ICOM 7300) and the toggle next to the display selects either VFO A or VFO B. The RED pushbutton engages the TUNE function. When this happen the display reads the transmitted frequency and the word TUNE appears on the screen. 

In normal Transmit (hitting the PTT or the MOX) right below VFO B appears the transmitted frequency. While many of those functions could be done with a 16X2 LCD -- you have a lot more real estate in a small size to display simultaneous information. 

ZL2CTM, Charlie Morris uses a similar display to show a "spectrum" of signals. but you would need something like a Teensy 3.5 versus the Pro-Mini that is being used for this application. I also took this opportunity to make some changes to the Arduino / Si5351 board. 

There are some interesting aspects to this rig. The IF Module uses a 3.180 MHz Crystal  Filter out of an early Yaseu FT-101 and the bilateral amplifiers are the Plessey circuit out of EMRFD. A cousin to this radio a 60M rig has many similar circuits only the Plessey amps are surface mount. The microphone amplifier is a germanium PNP transistor --just wanted to prove I could design PNP microphone amplifier circuits. 

The driver stage is also out of EMRFD but I use a 2N2222 TO-18 (so you can add a heat sink) and a BD139 in lieu of the expensive 2N3866. Works for me. Here is an interesting aside. The driver stage was built new BUT used a blank board that was originally the audio amplifier stage in my KWM4 (NE5534 and LM380). I realized that there was a circuit layout error so simply cut a new board after fixing the error but did Keep the blank board in the junk box. With a bit of juggling that audio amp board became the Driver Board.

The audio amplifier is the healthy NE5534 driving an LM380 (This has the proper board layout). Also an innovation: the bottom plate is a large piece of PC board which has been stiffened with aluminum side rails. There was a reason for this as the bottom plate is the heat sink for the IRF510 that is fitted with an isolating pad and simply screwed to the bottom plate. Copper is better as a heat spreader and you can verify that with your friendly EMRFD or uBitx illuminati.

Oh, the Band Pass Filter was originally used in the LBS transceiver project. So almost like a wedding something old (old boards), something new (new driver stage built on an old board), something borrowed (LBS BPF), something blue (the PNP audio transistor and the original LCD).

So a problem has turned into a better solution with greater capability. Throw out those LCD's and get an OLED or really go uptown with the Color TFT. For those who wonder --there is no OLED noise in the receiver! I am getting to believe OLED noise is like the phase noise of the Si5351 that was touted before it became an old wives tale.

Oh, not done yet --the sub-panel will be painted black today. That should make the OLED sort of disappear into the background. Done --- See below.






Pete N6QW






Friday, June 15, 2018

2018 ~ The Year of SSB Transceivers

7/10/2018 




7/1/2018




6/21/2018 ~ 6 and/or 4 Meters Your Band?





Yes you are reading that the displays are saying 6 meters or 4 Meters. There are many possibilities with the Arduino and Si5351. These are but just a couple examples. No, the 6 or 4 Meter hardware is not built but if you have such rigs and need a sketch email me n6qwham@gmail.com


6/18/2018 ~ More Possibilities






The code has been ported over to the Color Touch Screen and the 160X128 Color TFT. Lots of possibilities!

Pete N6QW



6/17/2018 ~ New and Improved Code

(Up on the link)

No Flickering of the Display !~ Thanks DuWayne KV4QB!


6/16/2018 ~ Two VFO Code: 160X128 TFT


Follow the link and look for the Simpleceiver project. There you will find a link to the code where the code is a notepad document. Copy and paste into an Arduino sketch. Note below:



  • The sketch is made with Arduino IDE 1.8.5
  • The display is a 160 X 128 Color TFT
  • You must have all of the libraries in your Arduino directory for this to work
  • You must also have the "included files" in the project folder for the sketch to include Rotary.h, Rotary.cpp, si5351.h and si5351.cpp. You can find these files under the Bitx40 link (on the website)  and these too are in notepad form.
  • This is provided for you as a roadmap of what I did. Quite honestly --it works for me but I am not an Arduino expert --simply a Radio Genius. 
  • Do not take me to task for not having elegant code -- I will leave that to you EMRFD and uBitx illuminati. But what is shown is a workable two VFO rig. If I knew what I was doing the code task would have been a lot easier -- but the bottom line I have it working on three different types of displays. By and large the Touch Screen was the easiest to implement 
  • Opening the connection that is made to Pin D4 (with another 1N4148 in line with the wiring with the Cathode connected to the PTT connection) will provide a functionality of independently transmitting/receiving on either VFO A or VFO B. So now the options are 1) Transmitting/Receiving on VFO A, 2) Transmitting/Receiving on VFO A but independent receive on VFO B and 3) Independent Transmitting/Receiving on either VFO A or VFO B. However some of the display status info would not be available with option 3 -- but the rig will operate normally. I may internally mount a switch inside the box so I could engage option 3.
  • You will need one external relay connected in series with the switch that selects VFO A or VFO B. This relay is opened during transmit so that while you can receive on either A or B you will transmit on VFO A. The relay coil is energized off of Pin D7. The relay is a 5 VDC unit with a 178 Ohm coil --doing the math (E = IR) that means the current draw is 28 Ma. The max current draw form an Arduino pin is 40 Ma.
  • I received a "concern inquiry" as to the relay coil connected directly to an Arduino pin. While I did not previously mention this, I have a 1N4148 "Snubber Diode" connected across the relay coil with the cathode connected to the Arduino Pin.  (Pin D7)


73's
Pete N6QW

6/15/2018 More on the Color TFT Displays


Part II of the New Dual VFO Simpleceiver.




The Paint Over is Resolved!

73's
Pete N6QW

Saturday, April 14, 2018

2018 ~ The Year of SSB Transceivers

5/6/2018 ~ Update


I Love the Smell Of Napalm in the Morning!

That specific line came from the actor Robert Duvall in the movie "Apocalypse Now" but is reminiscent of May 7, 1965 when as a member of MCB 10 [Mobile Construction Battalion Ten ~ SeaBees] and part of Regimental Landing Team #4, we made the very first amphibious landing since the Korean War. 

The landing zone was at Chu Lai, [at then South Vietnam]  some 90 "clicks" south of DaNang. Several months later (July 1965) I remember sitting on the veranda of the "homebrew" officer's club where at about 6 to 7 PM we would, with drink in hand, watch the nightly napalm run south of us on  Dung Quat Bay. Our camp (originally called Camp Shields) is now the site of a KIA plant as a part of the Chu Lai Open Economic Zone. My how times change? The 10K foot long  airfield that was built by RMK is now known as Chu Lai International Airport
Here are some photos that have survived ....


Lt. (jg) Peter G. Juliano CEC, USN Chu Lai 1965

Yes guys that is me about 53 years ago --also note I was  a "regular" and seriously contemplated a career in the US Navy. Two trips to Vietnam convinced me that was probably not a good idea. Note the "squared away" US Marine style hat. I even spit polished my combat boots. The gig line was straight and the blouse was "dressed". Noteworthy I was picked up 'early for full promotion to Lt. CEC USN. 


The above photo is the "Officers" shower facility and the man near the right hand center of the photo is taking a "whiz" into an outdoor urinal. This device invented by the Seabees is comprised a 12 inch diameter piece of PVC pip sunk into the sand and that is it. I must admit that after a few drinks the 12" target was hard to hit and the same problem late at night.

The next photo taken in 1965 should conjure up thoughts of the movie and TV series "MASH" -- I think the movie stole our lifestyle. That is my rack in the corner of the hut. Please note that my 782 Gear is packed and at the ready. Oh there are those asking what is 782 gear. Well the Seabees worked closely with the US Marines and adopted many of their processes and procedures. The term 782 refers to the form used to delineate the field gear that a US Marine (or Seabee) is issued. Typically this is a pack, helmet, entrenching tool etc --you know 782 gear.


Pete's rack and living space in 1965. I used to sleep with my 45 under my pillow. Funny story about that as in December 1965 I was selected to be the OIC of the advanced party for rotation back to the states. Because our battalion had been dramatically augmented by about 20% the day before I left I was asked to turn in my weapon as they were short of guns!

That very night our camp was attacked by the Viet Cong and we actually had VC inside the camp --and here I was without my issued weapon. At that time the sort of loose rules were you could have a personal side arm and I did have a .357 magnum which luckily was handy. Here I thought I was about to go home it might have been in an aluminum box. It was scary. I sort of wished I had a grease gun as a few of the guys did have those.

I do have to mention that our most significant piece of communication gear was a Collins AN/PRC-47. Which only went to 12 MHz and USB and CW. But I did manage to get some listening time in the radio shack and thought how cool it would be to operate from south Vietnam. We did have a Collins ham station KWM-2 30L1 but because it was so early in the war --prior to our getting there the total US forces were only about 10,000. That May it jumped to 20K so MARS and other stations were just getting approved. 

Too bad some our government leaders never spent time on the front lines. But we all know that story.

73's
Pete N6QW


Improving the Prototype #1 4/29/2018!


Starting by doing some analysis I looked at two possible factors that would improve the low frequency transmitted audio response and we have two significant players among many.

1. First is the Filter Bandwidth. I am now using a Ladder Filter where all the Capacitors are the same. Initially that was not the configuration. The values of the five capacitors play an important role in the bandwidth as lower values make the BW wider and higher values make it more narrow. For the reworked filter the values of all five caps in 68 PF. I did find that this change opened up the bandwidth and that is obvious in tuning across signals. Further evaluation may find that some sort of happy medium may be in the 75 to 82 PF range.

The filter changes make obvious better/worse conditions on the receive end --- but there are other factors that affect the transmit side including the filter.After making several contacts it was found that the signal reports were quite good with excellent characteristics in the mid to high range (a DX machine) but still a little low in the lows. This lead us to the other player in this game

2. The second factor is the response of the audio amplifier stage, which in this case is a single 2N3904 -- a bare bones stage. This is where having LT Spice at your fingertips is a critical tool. BTW just got it re-installed on my new computer after struggling to get the new libraries for the JFET's to work which now includes the J310. 

So here is some data for you. I have reason to believe the first prototype has this stage installed.



In looking at the plot data we can see there is about a 6 dB variance in the signal level at 300 Hz below what you see at 1.2 KHz. So that is why perhaps we are seeing the lack of lows.

Now if we diddle with several of the capacitors we get the following plot. Now the signal level is flat from 300 to 3kHz. Much better!


The revised schematic involves changing 3 Capacitors.

I will physically make those capacitors changes and report the results. LT Spice is an amazing tool and a few minutes with the computer let's you fix things.

Get cracking -- time to build this rig.

73's

Pete N6QW


Another Transceiver on the Boards 4/25/18

Yes it is on the boards -- breadboards.





Often you hear me talk about building several versions of transceivers with the 2nd version having the value of the "learning and improvements" from the first version that is incorporated in the later version . You see that later on in this post with the Shirt Pocket Transceiver.

One of the most successful projects I have undertaken was the Simpleceiver Plus which was completed in late 2017. That was version two and the version one prototype was simply put on the shelf. One of the main differences between versions was the crystal filter and the filter frequency. Version One was a four pole homebrew filter at 12.096 MHz and Version Two was a commercial 9 MHz six pole filter. Most of the other circuitry was the same with the exception of an SBL-1 used in V1 for the Rx/Tx mixer and in V2 it was an ADE-1. 

Critical to the success of this project was the use of J310's configured as a Dual Gate MOSFET. I also used extensive relay switching of the signal path proven with V1 so that in the final form there are essentially three Dual Gate MOSFETs that are the heart of the project. One J310 DGM serves as the receiver RF Amplifier while also serving as the Transmit Pre-Driver. A Pair of J310 DGM's act as amplifiers ahead and following the crystal filter. Relay switching essentially uses a single pass system so that on receive the signals coming out of the Mixer stage pass through the amplifier block onto the Product Detector. On transmit the Product Detector is now the Balanced Modulator and its output is relay switched to the input of the first IF amp. The output of the second IF amp is directed to the Mixer stage and then on to the former Rx RF amp which is now the Transmit Pre-driver. The signal is now switched to transmit RF amp stages.  LOTS more relays but lots less circuits. 




Two days ago, while looking for something entirely different, I spotted V1 sitting on a shelf, looking somewhat forlorn as I had robbed a few parts from the transmit linear amp stage; but otherwise unmolested. Given this was such a critical development tool for the later project, it was time to make it whole again.

About 10 minutes worth of work involved with liberating some boards from yet another project and the Version One was back on the air. A few on the air contacts with some of the Flex6700 ops indicated that the signal sounded OK but seemed a bit narrow lacking the lows they like to hear. There were no comments about distortion or burbles or spurs just that it sounded narrow. The further comment --it would be a great signal for busting pileups but for the "40 Meter Illuminati " a bit narrow. 

I looked at the coupling caps that were originally used in the homebrew filter and concluded that the filter would indeed be some what more narrow than the 2.8 KHz the Flex guys like to hear. My calculations indicated about 2 KHz bandwidth. So about 10 minutes of additional work and some new caps resulted in a  a newly refined homebrew filter. I can tell the received bandwidth is much wider .

Last night about 8 PM local left coast time --the 40M band was wide open and I made about a half dozen quickie contacts --some sort of contest. Half of these contacts were with east coast stations including one right in the heart of PA District 8-- Connor Lamb country. BUT there were a  few unsolicited reports -- like "you have a great sounding signal." So those are some data points; but we need more rigorous data collection before declaring victory. That I hope to do today. BTW --no QRP during the operation last night --was running 600 Watts. For those who wonder -- no beam just a droopy dipole with an apex at 25 feet. 

Using the SEARCH function on this blog type in simpleceiver for the many details of the build.

Some Photos of the "Al Fresco" build: [Yes that is a breadboard C Clamped to the work bench.]

The Rig 

The Display


EMRFD Driver and IRF510 Final

The Mess ~ But it works so well!
There is a total of 8 boards and with a bit of effort can be made a lot more compact. That is the plan. Get crackin -- you can build this rig.

73's
Pete N6QW

N6QW Innovative Transceiver Projects!

One of my goals for 2018 is to share information about my past projects in hopes that other homebrew enthusiasts will take up the iron and "roll their own" Many of the projects go back over ten years; but are relevant today.

You can make great contacts using homebrew gear! But I should caution you that you may get comments from the other end such as "well I am looking at your signal with my FlexRadio 6700 on a 72 inch screen and it appears you are 10 Hertz low in frequency". You gotta have thick skin--just think your rig cost $100 and his maybe $10,000. But even being 10 Hertz low --you are still having a QSO. 

There are three specific projects I would like to cover today and these include the following:

The first is a 20 Meter SSB transceiver that used MMIC's (Monolithic Microwave Integrated Circuits) arranged in a bilateral configuration. There were six total MMIC's employed in three sets of two for the bilateral amplifiers. This was kind of leading edge in 2011 for a homebrew ham transceiver. Initially I used a VTO (varactor tuned oscillator) but later this was changed to a Si570 VFO via a K5BCQ kit. [This was another rig given away when I had to move in 2013.] This by my definition an innovation in a ham rig.]

The second rig is a 17 Meter SSB Transceiver originally built in 2007. The innovation here was to use a crystal switched Super VXO to give a wide frequency coverage. The innovation here was the selection of the IF 4.9152 MHz and using 11.52 MHz crystals in a diode frequency doubling Super VXO circuit produced a signal; a 23.04 MHz and in doing the math 23.04 - 4.9152 = 18.124 MHz. Using the doubling circuit gave twice the swing in a Super VXO circuit. That worked so well that I custom ordered additional 11 MHz crystals so that I can cover almost the whole 17 Meter phone band.

The third project was a Shirt Pocket Sized 20M SSB Transceiver which was built in two versions with the first requiring a rather large pocket. The second version is 2X2X4 inches --still needing a big pocket. A third version planned for 2018 is to be Altoids tin sized. This rig also employed a 4.9152 MHz IF and this time a crystal switched heterodyne VXO. The first version in 2017 was retrofitted with a Si5351 and OLED Display.


Some Project Details:

The first is the MMIC Transceiver which was the very first "big time" article I ever wrote about one of my projects --this even made the cover of QRP Quarterly. The embedded you tube video was made at the time the rig first had the VTO and the drift is pretty apparent. It was real crap. The final version with the K5BCQ Si570 VFO kit --was like night and day. I regret having to give this rig away when I moved. In 2017 I used the bilateral MMIC stage in a compact 20 Meter SSB transceiver. The AG-303-86G is a superb device. As I mentioned in the article I got help with the bilateral circuit from a ham at Tri-Quint who was the manufacturer of the MMIC.

In passing at times you bump into things that amaze you. A friend sent me an eBay listing for the AG-303-86G MMIC device from a seller in Israel. In the ad, my schematic for the bilateral stage was featured to show how they could be built into the circuit. The MMIC's are termination insensitive good from DC to 6 GHZ and feature 20 dB gain. Should mention that the data sheet includes the required resistors for various sources voltages which enable you to run the devices on anywhere from 5 to (I think ) 9 VDC. I picked  5VDC. Another neat feature of my circuit is diode steering so that when you "bias on" the MMIC that also steers the signal right left or left right. So OK another bit of innovation --for 2010.

To the best of my knowledge I am unaware of any other homebrew rig which used MMIC's in a bilateral configuration in 2010. I am sure there are commercial designs but my application may have been a first. I am sure blog readers will let me know otherwise.

In the last photo is shown the MMIC board (underneath the green perforated board) and a shot of the completed rig. There are two stories here (actually three) with first being the suitability of the MMIC's for our beloved rigs. The second is that the MMIC's can be effectively used in a bilateral configuration and the third -- great for making compact rigs.













The 17 Meter SSB Transceiver Project:



The second project is a 17 Meter SSB Transceiver first started in 2007 where some fundamental circuit blocks were initially developed that found their way into future projects. The heart of this rig was a bilateral amplifier circuit developed by G4GXO [SPRAT # 128] which used either a Dual Gate MOSFET or two J310's configured as a DGM.

Based on some information gathering in preparation for the build, I discovered that in the Elecraft K2 the IF Frequency was 4.9152 MHz. Hmmm good enough for Elecraft so good enough for me. This was a wise choice as I soon discovered that using a stock computer crystal of 11.52 MHz in a diode frequency doubling VXO circuit produced an output at 23.04 MHz. The frequency scheme in a down mix resulted in tuning smack in the middle of the 17 Meter Phone band. Subsequently I purchased special frequency commercial crystals that provided the upper phone band coverage of 17 Meters. A trick I used was to switch the VXO crystal banks was a relay that was controlled by a panel mounted toggle switch. Thus I had a high range of VXO frequencies and also a low range. The yellow cube in the photo below is a DPDT 12 VDC DIP Relay. Because of the frequency doubling two crystals per range in the Super VXO Circuit provided a large frequency excursion.  

Also note the use of single sided copper vector board where a solid ground plane is the norm. After using this (somewhat expensive) medium you never think of Manhattan construction for projects like this. All wiring is point to point underneath the board. With some circuit noodling of the layout it is possible to achieve a layout that minimizes the circuit wiring and reduces the possibility of unwanted coupling. Some nice innovations here.




Complete details of this transceiver can be found on my 2nd Website Believe it or not this project started out as an attempt to build a shirt pocket SSB transceiver which resulted in a working rig; but definitely not something to fit in your shirt pocket. The boards above were finally fitted into an aluminum chassis measuring 7X7X2. There is room in that chassis to fit an Arduino/Si5351 and an OLED Display. That is in the queue.






The 20 Meter Shirt Pocket Transceiver:

As I stated earlier my initial quest to build a shirt pocket SSB transceiver started in 2007; but it was not until 2011 that I arrived at a shirt pocket sized transceiver. A rig 16 cubic inches is small BUT you still needed a large shirt pocket --Paul Bunyan sized more like it. In 2018 I am looking forward to building this same rig into an Altoids sized tin. 

In 2011 I was overtaken by the desire to really get serious about a shirt pocket sized transceiver. W3TLN, Ed Vester built an all solid state SSB rig running 100 Milliwatts on 20 Meters that ran off of 6 VDC. The choice of 6 VDC was because it was a mobile rig fitted into a Volkswagen Beetle -- an early version with a 6 volt battery. It was a small rig and used a homebrew crystal filter and a VXO. The Vester rig was published in a QST article and subsequently published in the ARRL Sideband Handbook. 

I built the Vester rig in the 1970's from the ARRL Sideband Handbook. But I could never get it to work. In the course of preparing some articles for QRP Quarterly, in 2010 I mentioned to John W5DIA about my non-success with the earlier project and he sent me a photo copy of one of the pages in the original article. BOOM --the article and the Handbook version schematics were different. That was my problem! I had a difficult time reconciling how there could be two different versions of the same schematic --in a QST publication...


Thus having found the problem with the Vester rig I decided that I would just build my own version -- the Vester rig was 7x7X2 --not a shirt pocket rig.

I built two versions of the shirt pocket rig with the idea that the first version would be the proof of concept and the second would capitalize on that experience to make it really small.

The is information on my  website  http://www.jessystems.com/20MSHIRTPOCKET.html about this project including some schematic diagrams. This project also was a subject of a QRP Quarterly article. 

Noteworthy the original rig used the same crystal switched VXO approach as in the 17 Meter Rig  with a twist in that the Super VXO operated at 12.906 MHz and was mixed with crystals in the 6 MHz range to give about a 120 kHz spread on 20 Meters. The reason for this choice/approach was the availability of standard computer crystals.







Fast forward to 2017 and these rigs have been further modified with new case colors and Version 1 and been retrofitted with a an OLED/Si5351 and Nano digital LO.



This is a lot to absorb ... but is provided to open up a view of the homebrew possibilities. It goes without saying -- most of these are not first time projects but they do offer an insight into the amazing (and cheap) technology that is available to us today.

73's
Pete N6QW

Like a slap in the face!

I was trying to balance my checkbook over the weekend and was off by about $100 or something shy of 14 gallons of gas here in Southern Calif...