Wednesday, November 15, 2017

21st Century Homebrew SDR SSB Transceiver Project

Roll Your Own SDR SSB Transceiver


N6QW Moves Totally to the Dark Side of the Hobby!


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.

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.
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.
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.
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.
From the Dark Side
Pete. N6QW

Wednesday, November 1, 2017

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.
Pete N6QW

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

Note new email address as of 11/12/2017:

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.

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 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.

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
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!
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.
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.

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).

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.

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

Pete N6QW

Monday, October 23, 2017

Simpleceiver Plus SSB Transceiver ~ A new DifX

The Simpleceiver Plus SSB Transceiver is on the Air!

10/29/2017 ~ Stations Worked on the N6QW Simpleceiver Plus SSB Transceiver CQ WW

  • JA7FZN
  • JR2GRX
  • AH6BT
  • 8P5A
  • XL5T
As you can see I am a big time contester. But I sure could hear lots of stations and so am delighted with how this homebrew project has turned out. The XL5T was worked running about 6 watts.
Have some parts on order which should arrive next week (mid-week) and hope to start construction of the V.2 Simpleceiver Plus SSB Transceiver. Essentially the circuits are mostly on a single PC board and will have a 9 MHz IF. I will share that info on this blog
Pete , N6QW

10/28/2017 ~ Another Simpleceiver Plus SSB is "On the Air"

Here is the text of an email I received from Jelle, PA3GUP, this morning;

Hi Pete,

First 3 contacts in the log

M6T, 222KM

DP6T, 369KM

OK7K, 692KM

All with 10watt and a small dipole.

best 73 Jelle, PA3GUP

So OK time to get off the couch and get with the program. I was happy to hear about Jelle's success. That said this morning running 600 watts and my Simpleceiver Plus SSB Transceiver during the CQ WW DX contest I worked several JA's in the contest and that my friend is about a 5000 mile trip from this QTH.

I have a Version II in the works and will share that with you shortly. This one has a 9 MHz GQRP Club Crystal filter versus the 12 MHz homebrew filter. My plan is to not cannibalize Unit #1 as V.2 will be a separate build.

Pete N6QW


10/26/2017 ~ N6QW is NOT on 630 Meters!

We have all heard the axiom" If it walks like a duck, Looks like a duck and Quacks like a duck --Then it is a duck!" That is not always true.
Imagine my surprise when VE7SL, Steve, emailed me an inquiry if I had by mistake called up 600 Meters in WSPR settings when I actually was copying 40 Meter signals and reporting them as 630 Meters.
Well I don't know what to say? I did have Power SDR set to General Coverage and cranked down to 0.474200 MHz and there were signals showing up on the waterfall. So there is that Ghost in the Machine.
I simply can't explain it other than the possibility of a problem with the Si570 LO. One shortcoming of the Si570 is that the lower frequency limit is about 4 MHz as opposed to the Si5351 where it is 8 KHz. Since the LO is set for 4 X the actual frequency (prior to being injected into the SN74HC74) that would mean the LO would operate at 1.8968 MHz which is below the 4 MHz threshold. So that might be the issue.
I did have the Rx set to 0.474200 MHz so it was not like I called up WSPR for 0.474200 MHz but actually tuning 7.038600 MHz. Another one of those challenges.
But that said --I have used the same front end to copy WSPR on other bands. So it remains a mystery. Guess I best stick with what I know.

Yes I am now listening to 630 Meter WSPR signals. The Receiver is HOMEBREW using two J310's for the RF Amplifier stage and the Detector is a pair of ADE-1's. I homebrewed a signal splitter using a type 43 ferrite core balun and the LO is supplied using a kit called the QRP2000 which drives an Si570. The Si570 can be acquired as a sample [free] from Silicon Labs and the LO Board comes as a kit less the Si570 for about $20 (From the UK).
The output from the Detector board is fed into an M Audio Delta 44 Sound Card and the SDR software is the Power SDR V2.4. The computer is an Intel Atom at 1.8 GHz. WSPR 2.0 is being used. In case you are wondering the antenna is my 40 Meter droopy dipole with the antenna tuner bypassed -- about 92 feet long.
Bare Bones Receiver Front End
First Light
Now Several Stations being Spotted

I have reason to believe with a few more boards I can turn this into a full transceiver so that I can transmit as well on 630 Meters. Have made the license application and now must await several more weeks. BTW this homebrew SDR Receiver is also useful as a piece of test gear. The LO is generated at 4X and I am using a SN74AC74 to provide as divide by 4 to the quadrature detectors.

Man this band is really HOT!!! Just look at the spots and that has been in the last half hour. Just imagine --a hand full of parts and a bit of tribal knowledge coupled with a lot of luck can get you on 630 Meters. Hope I can get a transmitting license. Best DX (just updated) is about 2500 miles and he was running 5 Watts from Hawaii. Who says you can't work the world on low power. Actually my idea of QRP is about 500 watts just to be safe.

Stay Tuned! Oh in case you are wondering there are no plans for 2200 Meter operations (at this time).
Pete N6QW

10/25/2017 ~ Another Simpleceiver Plus SSB Transceiver On the Air

PA3GUP's Simpleceiver Plus SSB Transceiver

I received an email from Jelle, PA3GUP who shared a photo of his build of the Simpleceiver Plus SSB Transceiver. As explained in his email, it is exhaling RF and lacks only a driver stage capable of 30 MW to drive an outboard amp for QRP operation.
Noteworthy is his construction technique complete with breadboard and nicely built modules. Liberal use of SMA interconnects and coax keeps everything neat and tidy. I note his use of angle stock (a favorite of mine) for mounting panel controls.  It looks like the angle stock has many holes for different sizes of controls and/or IO devices. Bravo, Jelle!
Of special note is his construction of the homebrew crystal filter! This is the way to do it! The connections are short and the filter is mounted over a ground plane. What is important is that the signals are going THROUGH the filter and not around it! It is also low profile so that when you want to compact your rig -- it will fit almost anywhere in your chassis box. I note the use of both SMD and leaded components --mix and match --whatever works! [See the photo below.]
I will be most interested to hear from Jelle about his first contact with the Simpleceiver Plus SSB Transceiver. His closing note to me was that he as a "Very Happy Camper". So you couch potatoes --heat up your iron and get a soldering!


Pete N6QW

In an attempt to complete this project here is the future plan.

  1. I will document the project fully with all schematics and this will be done using my website
  2. The effort on the project will be kept open only insofar as those following along with the project will complete their builds. Don't want to leave you out to dry.
  3. I will be doing some additional peeking and tweaking of the circuit elements to insure maximum performance.
  4. Email me with any questions to
Stay tuned for some fun with my homebrew SDR rig being run by a Raspberry Pi3.

Pete N6QW

Wednesday, October 11, 2017

Simpleceiver Plus SSB Transceiver ~ A new DifX

A Move to the Simpleceiver SSB Transceiver.


The Simpleceiver Plus SSB Transceiver is on the Air!


10/22/2017 ~ The Simpleceiver Plus SSB Transceiver 1st QSO with W1AW/6

It does not get any better than this -- imagine my surprise when at 9:30 AM PDST on 7.185 MHz I heard W1AW/6 calling CQ --several times. I could resist no longer. Gave him a call and the Op Marty, called me back. Boom! The Radio Gods Have Spoken. My very 1st QSO with the Simpleceiver Plus SSB Transceiver and it is with W1AW/6. This was a special events station at San Ramon, CA  (SF Bay area) in connection with Pacificon (a Ham Radio Event). I was running 500 MW with the EMRFD Driver board and my report was 5X8.
Needless to say the most amazed person was me! San Ramon is about 350 Miles form the N6QW Newbury Park Laboratories. So OK -- here is a photo -- it looks like crap but works like a bomb!

The EMRFD Driver Board is at the Top Center off the bread board. I did not even have the TR relay set up so the Driver board is connected to the antenna and I was using an outboard receiver where I could switch my droopy dipole between the board and the external Rx. Today I need to get the TR relay installed and the LPF. You can see I was all set to install the LPF (The three toroids were wound just this morning and are lying just to the right of the board.)
This was an exciting day -- the Simpleceiver Pus SSB Transceiver has many innovations and what you see in the photo above is pretty much the Superhetrodyne Receiver with a  few relays, a microphone amp and the driver board. Go get off the couch and heat up that soldering iron!

More Photos -- had to add a small T Type attenuator pad on the EMRFD driver stage when I discovered a RF feedback problem when it is used with an outboard linear amp. The issue was I had to lower the gain on the pre-driver to prevent the RF Feedback but that then lowered the receive gain of the stage. The Pad lets me run more gain on receive and solves the RF feedback issue.

The RF Amplifier board used both on Rx & Tx

The IF Block that uses the relay switching for Rx and Tx

The EMRFD Driver board with a 5.5 dB T Type Pad on the input [ 2X 15 Ohm and 1 X 75 Ohm]


PD/BM with the single 2N3904 Microphone Amplifier

I now have it rigged up with 2 in-line amplifiers and it will run 200 Watts output. Several additional contacts were made today at 10 watts with stations in Arizona and Nevada. Go Simpleceiver Plus SSB Transceiver! So far about a half dozen contacts today.
Pete N6QW

10/21/2017 ~ Addendum On the RF Stage Switching

Works flawlessly and produces 1.64 Volts Peak to Peak across a 50 Ohm load which is 6.72 Milliwatts. Next I will test the EMRFD standard driver stage (2N2222 and 2N3866) to follow this stage and see what that output looks like. It may be enough to try some QSO's. The output is clean and sounds really good. Yes I did look at the signal with my homebrew SDR receiver and Power SDR. This is exciting.
Pete N6QW

10/21/2017 ~ First Look at Switching the RF Amp Stage for Rx and Tx

Here is a first look at using our J310 Dual Gate MOSFET Stage to also work as the Transmit Pre-driver stage. Again the surplus Omron G5V 5 VDC SPDT relays are doing the heavy lifting.
The above schematic is my first prototype and I will be wiring that up today. The beauty of the relay switching is that we use the inherent circuits of the Superhetrodyne receiver blocks in the Transmit stages. This means minimum building and ease of construction. Stay tuned we are inching closer to an on the air transceiver.
Pete N6QW

10/20/2017 ~ Houston we have Ignition -- The Simpleceiver Plus SSB Transmitter Portion of the Transceiver is Working and Exhaling RF!


Exciting news! The Transmitter is working and for your own amusement and amazement you can see it working here. It was an exciting day at the N6QW Newbury Park Laboratories.
Some noteworthy mentions. The relay switching of the IF block module works beyond my expectations. Plenty of RF coming out of the block which now has me thinking the receiver RF amp stage could similarly be switched with two relays so that it would function on both transmit and receive. Two more blocks (low level driver stage and LPF) would yield an actual working 300- 400 MW QRP transceiver. I also found that the LSB BFO frequency seems spot on but the USB needs to be adjusted. I need to go back into the code and adjust the frequency so that the USB does not sound pinched, which you can hear on the video.
Keep in mind that by adding just a simple one transistor microphone amp and adding now 4 relays you can turn the Superhetrodyne receiver configuration into a working SSB transceiver.
In the next post I hope to  get a chance to include the schematic of the microphone amp and how I wired up the RF amplifier with the two additional relays. For those who can't wait visit my website at and link on to the LM373 transceiver project and one of the linked schematics is the microphone amp.
Pete N6QW


10/18/2017 ~ Troubleshooting the Simpleceiver Plus SSB Transceiver

Soon we will be having a complete transceiver and that is usually where the fun begins. No, at this point I am not addressing the fun side when you make contacts; but the agony when something isn't working and it drives you nuts. We all know that fun!
I want to share with you two stories from my earlier life that while they are not directly related to ham radio none the less tell a powerful story about when confronted with trouble shooting problems.
Taking the time machine back to 1966 I was a Lieutenant in the US Navy [For those who wonder I was USN not USNR.] Being chronically sea sick I was assigned to the US Naval Civil Engineer Corps. (SeaBees guys). In 1966 I headed a small group of principally Chief Petty Officers (most were Master Chiefs and thus at the highest enlisted rank) who each had a specialty in the construction trades. These specialties included builder, utility man, electrician etc. Our job was to assemble stateside, a complete camp that would be shipped to South Vietnam. Typically we were given a number like a 500 man camp at location X and then we would essentially assemble the parts for a "Giant Heathkit" that would be shipped to location X.
Because the Vietnam War was ramping up so quickly, we were forced to purchase COTS (Commercial Off The Shelf) products such as pre-engineered buildings. Perhaps you heard the term Butler Building which happened to be a specific manufacturer. But there were others like Strand Steel or Soule and others. These buildings were typically 40 X 100 square feet and while all manufacturers had s stock 40 X 100 foot buildings, the actual steel support structure was different and the "bents" typically were spaced differently and the anchor bolt patterns were different.

A 500 man camp may have a half dozen of these buildings. Often slabs were poured before the actual buildings arrived on site. In one of these "kits" might be buildings of several different manufacturers. Thus we got a lot of grief from the field battalions about the wrong pads for the right buildings.
Back to our Master Chief Petty Officers --a unique breed all of their own. One of them came to me and said I am going to lunch, I am going to drink until I get drunk and I will solve this problem by tomorrow! He then said I assume you have no questions about what I am going to do. The next morning when I came to work there he was and he looked like hell -- obviously he had a lot to drink. Then he says about 11:00 PM the prior night he came to the office (half in the bag) and developed his solution. It was brilliant!
The solution involved creating a new universal drawing for the 40 X 100 foot concrete slabs that had embedded anchor bolts spaced apart for every pre-engineered building we used. Thus when the slab was poured extra anchor bolts were installed in the slab. When the building showed up --you simply used the magic decoder chart and cut off the anchor bolts that were not needed. About a half hours worth of work with a torch and you were ready to install any building that was delivered.
After that I frequently encouraged the Master Chief to take a long lunch hour! He was the guy who changed the Bill Of Materials to 29 common items. Initially we had four different sizes of hinges in the kits --he asked --WHY? Supply one size of hinge and it will work anywhere. We stopped supplying 4X4's and if you needed a 4X4 make it from two 2X4's This was advanced base construction not building luxury homes in Beverly Hills. The guys in the field appreciated this too as the parts shortages went way down as you only had to deal with 29 items!
We not only assembled the kits but we bought the parts --I can tell you there were over 5000 of those buildings that were bought! His solutions saved us countless man hours.
The next story took place after I had left the Navy and was working for Boeing in Everett, WA, home of the 747 manufacturing plant and the world's largest building by volume. I joined Boeing when 747 Ship #1 was going final assembly. You can't imagine the energy and excitement that filled the plant. Ship #1 typically is not sold, but is used as a flight test vehicle. As an airplane is moved down the assembly line it frequently is raised on special jacks so that access can be gained to areas that are not accessible in the normal mode.
As luck would have it as Ship #1 was nearing completion of final assembly it slipped off the jacks and one of the jacks penetrated the wing in the area of one of the fuel tanks. Disaster! Catastrophic was a common catch phrase. Most of the VP's could only think about the hit to the stock and their incentive compensation. Some of the brilliant young engineers suggested that in a month they could cut off the wing and install a new one. A month? Well finally someone said lets ask Bill Geist (he was my boss's boss).
Bill came down to the final assembly area and started laughing at what he heard being suggested. Geist ran the manufacturing line for the B-17 during WWII and planes slipping off jacks was routine. He said here is how you fix that problem --boom it was about 16 hours worth of work, which was the standard fix for a B-17 jack impalement. Once again Tribal Knowledge to the rescue.

Bill's comments were that this was Ship #1 and it would never be sold --so who cares if there is a patch on one the wings --not even visible. The program had only a slight 16 hour delay. The VP incentive stock was not hit and they even spun the story about the amazing Boeing Engineers! Bill Geist was not an engineer but sure knew how to build and fix airplanes.
So there is a ham radio aspect to these two stories as it applies to what we do in our hobby. Almost always there is a simple solution to  trouble shooting a problem. You might have to drink a bit to find it; but don't start by ripping everything apart. Also only change one thing at a time! Spend time thinking about what could be the problem and what clues lead you to the answer. Don't raise the bridge --lower the water.
Pete N6QW

10/16/2017 ~ Response to some questions.

The Ghost in the Machine has struck again and now it seems I can't respond to questions that are posted. So I will do it this way
  1. I used two relays for some specific reasons. One is of course thinking they would be better for the isolation issue and 2nd -- That is what was in the Junk Box. I do think this isolation is an issue as I found that was a problem when I used the diodes. The diodes did not prove as good as the two relays.
  2. Following on to Jan's comments. Yes a pair of TIA amps does involve six transistors just as the J310's would require 4 for a pair of amps. Jan, I guess my approach has always been that there is never a single point solution. Often I see and hear comments that the TIA is the only amp that should be used or that the Bitx is the singular approach to building a transceiver. Today I have one Bitx and only one that uses the TIA amps. Thus about 20 or so other transceivers  use other approaches. The bottom line is to foster experimentation and trying new things.
Pete N6QW 

10/16/2017 ~ J310 Spice Model & Photo of IF Amp Block

I received an inquiry about how to find the LT Spice Model for the J310. I am not sure that LT Spice has updated the library with the J310 --keep getting a message about it being 764 days since I updated my LT Spice. Guys there is a very good reason why I don't do things like that -- I updated my Arduino IDE and none of my old sketches would work and in fact I lost some sketches. That was a disaster!
Now if you look carefully at this blog page you will see that long ago I added a Search Block. If you type in J310 Spice Model it will take you to a page about two years ago called Simpleceiver 7 and on that page is a link where you can find the spice models for many devices including the J310. [Do I have to do all of the heavy lifting? ] Anyway that page has now been updated to the following link:
So I guess it is now time for me to remove the Search Block as it obviously is not being used!
I have installed the two relays on the IF block module. I also installed a 7805 which provides power to the two relays -- tried it initially with just a 78L05 -- too much current draw with two relays. The 7805 is sitting next to one of the relays. I have yet to install the RG-174U cables which are used only on transmit but if I switch the relay --the receive signal is not in the loop-- so my quickie test tells me I wired it correctly. You can also see the board with the ADE-1 Product Detector / Balanced Modulator installed.
IF Block Module with Relays
Next to the ADE-1 is a blank area for the microphone amplifier which is the next build. Once I have the Microphone Amp built I can test the low level transmit stages. See there was a method to my madness. We are getting closer to having the transceiver built. Keep in mind how I earlier said that once you have the Superhetrodyne built that you were about 65% of the way to having the transceiver --now you can see why I said that.
Stay Tuned for more excitement!
Pete N6QW 

10/14/2017 ~ Switching the IF Block Module ECN #2.

In an earlier series of posts I detailed how to keep the IF Amplifier Module and Crystal Filter intact and arrange for the switching of the signal direction using diode steering. My first attempt at doing that raised some issues about signal isolation and thus am changing that approach to using two simple small relays. The schematic for that change and the notes explain how it works. The relays also make it easier to retrofit the board --lots less wiring and lots less parts. The relays are SPDT from Omron G5RV - 5 Volts. They were bought surplus form All Electronics here in California. I think the price was under $1 each.

 Hope you can read the drawing and the notes. Engineering Drawing was not one of my strong suits when I was in College.
We are getting much closer. I will install the 2nd relay tomorrow and take some photos so you can see.
Pete N6QW

10/12/2017 ~ A Question about the J310 Configuration

Jan Ciger posted a question about why use the J310 as the basic amplifier circuit as deployed throughout the Simpleceiver Plus project, versus using the Termination Insensitive Amplifier building block from Hayward and Kopski vintage 2009. That is a good question and so I will attempt an answer as to the "why".
Fundamental to the answer is how I build things. Several days ago I responded to Johannes in downtown Freiburg suggesting he build a second receiver that was not so nicely packaged on a single board. My suggestion was that he build another one made up of modules i.e. audio amp module, RF amp, Product Detector that in effect becomes a test bed.
Thus we introduce the  rationale for the concept of an Experimenter's Platform. By building in modules, it is possible to try new circuit elements without destroying the whole project. Another key factor is the use of you tube videos. You can film a baseline of performance and then when you make a change you film that as well. Boom you now have documented data like when you go to the eye doctor and are being fitted for glasses. Is lens A better than lens B?
A second point is that we started the Simpleceiver Plus Project with the concept of a very basic and universal common circuit template. The  building block layout for the RF amplifier (Transmit or Receive) was essentially the same as for the Product Detector as well as the IF amplifier blocks. This made possible the use of very common parts and a limited number of parts values. The use of LT Spice enabled fine tweaking of a circuit dependent on its use. I could evaluate an RF amp circuit using the J310's and then see how that works for the IF amp. Further I could adjust the gate voltage (or introduce a signal on Gate #2 when used as a Product Detector) and see the performance change depending upon the specific application.
Now I am beginning to understand the real issue! I am not a Farhan, Hayward or Kopski!  Nor am I well known in the ham community as they are. So why would I suggest the use of J310's configured as a Dual Gate MOSFET versus simply pressing on with the well documented and frequently mentioned TIA?
Obviously many homebrewer's have heard that Dual Gate MOSFETs are like ancient technology --so much so that RCA no longer makes the venerable 40673. Most DGM's made today are surface mount so another "bad feature". The TIA (Termination Insensitive Amplifier) circuit was specifically developed for use in bi-directional radio transceivers --so again why in the world would you use J310's --and who is the N6QW guy?
For your Dining and Dancing pleasure I have prepared a chart that compares some of the features and benefits of the two circuits.
In looking at the chart it depends what lens is in place ( A or B). The TIA has many fine attributes and is well known and revered in the EMRFD community. Besides the  J310's have not been used in  a broad band mode but rather specific use of LT Spice enabled the performance to be fine tuned for a narrow band of frequencies.
For the most part they are comparable in performance. There is one aspect that I do find as being a difference and that is the ability to use AGC or manual gain. There are several You Tube Videos where I demonstrated the manual adjustment of the stage gain in the RF and two IF Amps -- I thought that was pretty impressive!
Now for a moment back to the Experimenter's Platform. It would be an easy matter for someone with this burning question to simply substitute TIA amps for the J310 amps and decide which is better. I have built a 20 Meter transceiver using the TIA amps where initially I set the gain for the 15 dB (using the 1st set of resistors in their chart). I was underwhelmed with the performance in that there was insufficient gain and the receiver sounded deaf.
When I changed the two resistors (from the data table) in the TIA application note so that the gain was 24 dB then that was more like it. Initially I thought I had a wiring error or bad parts --nope 15 dB per stage was not enough. Keep in mind that you have 6 dB of conversion loss in a SBL-1 and there is loss in the SSB filter. By my WAG I had lost about 15-18 dB of gain in the two SBL-1's and the crystal filter.  Adding about 18 dB of gain (15 to 24 = 9, and 2 X 9 =18) made it work.

I hate to say this --but it is gain across the whole topology that is the key factor --hold back the gain of the front end (because you amplify the noise as well) and make up that gain in the IF and audio stages. Thus you may get the point of my having adjustable stage gain capability for the RF and IF amps.
While I have not measured any noise figure ( I don't think I would even know how to do that) but I can tell you and others have commented --the signals seem to "pop" out of nowhere and the background noise between stations is low. So I guess that counts for something.
For those who may not believe N6QW actually built a transceiver using the TIA amps see below. [So OK stop drooling --- it does look like a rather nice layout!]
Now Jan, back to your question. You need only to listen to the current You Tube videos and ask do the J310's configured as a DGM sound OK? After all it is how it works and not so much what is under the hood.

Maybe a more fundamental question would be would I ever use a TIA circuit again? The answer is it depends but more than likely not. My first choice would be the J310's followed by the Bidirectional circuit I developed using the Tri-Quint MMIC amplifiers. The Blue Rig at the top of the masthead has the MMIC amplifiers for one of the stages.  Given what is the Simpleceiver Plus project (a clue is in the name), the J310's were a clear choice.
Thank you Jan, for your question as I am sure others would want to know why I did what I did.
Pete N6QW
It is always best to start with a block diagram and this is shown below. You will note the blocks that are highlighted in yellow which reflect what is built so far. Noteworthy much of the built receiver becomes the transceiver.
I have posted several videos of the Simpleceiver Plus receiver configuration and I believe what you heard reflects the performance built into the design. Now look carefully at the block diagram you will see that many of the circuits are used both on transmit and receive. So this should be a huge flashing billboard that by working on the receiver and having it perform well will carry over to the transmit side as they are the same circuits.

What is not shown is the control/switching circuitry which will be detailed in subsequent postings. Thus it is imperative that you have the receiver working just as you heard on the you tube videos before starting the transceiver.

The next few days I will spend cleaning up the Simpleceiver Plus bread board by removing the original Product Detector and installing the ADE-1 onto the bread board. the plan is to take detailed photos so you can follow along with your build. We are getting closer.

Pete N6QW