Sunday, December 8, 2019

The Whaddon Mk VII - Paraset Clandestine Radio

What is a Paraset?

No I didn't say parasite but Paraset! 

Bottom Line the Paraset was a clandestine radio set built in England and supplied to agents operating behind enemy lines in the European theater during WWII. Most went to the French Resistance; but some found their way into the Scandinavian countries. 

It is believed that Torstein Raaby, the radio operator on the Kon Tiki voyage used the Paraset while a Resistance Fighter in Norway during WWII.

The whole radio was stuffed inside an innocuous looking scruffy suitcase. The standard issued radio even included some spare tubes right in the case.

What is up here?

At first I thought it would be nuts to rely on such a radio as your primary communications link with your headquarters. Then I forgot that the British had 10,000 National HRO Receivers parked about 100 miles away whose only job was to copy your signal and at the same time some very powerful radio stations sending RF in the other direction. So perhaps when the whole system is evaluated not all bad.

It was quite an interesting radio receiver / transmitter that I previously mentioned was stuffed into a small suitcase so that it would be disguised. 

There were several options for powering this rig including from the mains as well as from a DC power pack (vibrator supply). 

The basic scheme was a two tube (6SK7's) regenerative receiver and a one tube (6V6) CW transmitter crystal controlled operating in the 3 to 8 MHz range. The receiver tuned the same range. The power output of the transmitter was at best about 5 watts. Keep in mind friend Bill, N2CQR has made 20 contacts on 40 Meters running a one transistor regen and one transistor transmitter at 100 Milli-watts. Some DX is like 1000 miles away --so 100 miles with 5 watts is a cake walk!

The transmitter tuning used a two light bulb system (Load & Tune) for indicating maximum RF Juice to the antenna. For antennas don't think of 40 Meter dipoles strung between two trees at 100 feet. Often a chunk of wire was thrown on the floor or perhaps strung around a room.

Many hams world wide have taken up the challenge to replicate this amazing radio and the internet abounds with many replica examples of the Paraset.

I tried my hand at building just the transmitter section and found it to be somewhat underwhelming. I also did some preliminary work on the Dial Drive Mechanism which was friction drive controlling the main receiver tuning capacitor

Pete N6QW

Monday, December 2, 2019

Bitx40: ~ Replacing the Raduino with the N6QW controller!

Say What: Replacing the Bitx40 Raduino?

12-07-2019 ~ Pearl Harbor Day

Let us not forget what happened 78 years ago today. On a sad note there are but three remaining survivors of the original USS Arizona crew and only one will be attending the commemoration ceremony.

Many have sacrificed to make this the Land of the Free and the Home of the Brave! 


I have now added switching of an linear amplifier to the PTT circuit so I can run 600 Watts with my "reworked" Bitx40.  Two 1N4148 diodes and a 12 VDC SPST relay make it all happen. Running a bit more power does help.

My latest project now on my website...


I call my Bitx40 "Maggie May" since she has been passed around a bit and before transmitting I specifically looked at the Bitx40 documentation. Shazam -- The bias was at Zero and not set to 100 Ma, and there was no drive as such. Fixing those two provided 10 Watts of solid power output on 40M. I cranked it back a bit since it would see some heavy duty cycle operation on WSPR. 

My offer stands: any one wanting to dump their Bitx40 -- a crisp $10 Bill and shipping costs from a US address is my offer. C'mon guys rid yourself of that former play toy and let N6QW work his magic. 

Send me an email to the address on the masthead if you would like the sketch code. 

N6QW, Pete the Radio Genius

12-03-2019 ~ Digital Modes with the Bitx40 and the N6QW Controller.

Raspberry Pi3 and (not seen) N6QW Digi Controller being used with the Bitx40 and N6QW's Raduino Replacement.

A couple of key comments 

  1. This shows I must be close on the USB offset as both FT-8 and the WSPR were dialed in on their normal frequencies
  2. I did not transmit on either WSPR or FT-8 as you must modify the Bitx40 Microphone input circuit. The Bitx40 uses an electret microphone which typically has a DC bias voltage on the input pin. As I did on The Paesano, I added a Data Port -which is nothing more than a 3.5 mm stereo jack that has a 10 NF cap in series with the microphone port to provide DC Isolation. That has yet to be done. Works perfectly on transmit see last chart.
  3. So for those of you who have "put away" your Bitx40, with a few changes you can do "The Digi Dance" with your rig.
  4. My offer is still open if you would like to dump your Bitx40 -- a crisp $10 bill plus shipping and I will take it off your hands.
  5. WSPR on the Bitx40 with N6QW Arduino Controller.

  6. After three hours both transmitting and receiving

The Bitx40 being heard In Brazil and Sout Africa! Nice!

Stay tuned to this space for more exciting Bitx40 Modifications -- may be even 6 Meter SSB.

Pete, Radio Genius


Pete N6QW


Is this like blasphemy, heresy or on par with the Ukrainian Bribery scandal? No, it is none of those just a practical matter. 

In a recent Soldersmoke Podcast #215 the fact was made known that the Bitx40 was no longer in production. I then said if anyone wants to sell me one for about $10 contact me. That offer is still on the table!

Well my good friend N2CQR sent me one that had been passed around a bit (you know like Maggie May and the high school football team). Well when I connected all I soon discovered that Raduino was not providing any RF. The pot tuning also left me wondering even if it did work would I be happy.

So I took some parts, took some software and when you know stuff you can do stuff!

I started 1st with a 5 MHz PTO from a Drake TR-7 and that was to quickly establish that the main circuit board worked and was the Raduino the only problem. That was accomplished. 

Next was to get a basic Nano and Si5351 to produce the LO signal which was also to prove that my LO was correct and that a first stab at the BFO frequency was at least in the ball park. Keep in mind that not all Bitx40's are exactly alike. I think initially depending on Uma's crystal sorting there could be as much as 3 BFO frequencies.

Finally after passing the LO test I added the BFO. This test proved that the LSB BFO is very close but I may need to tweak the USB -- next phase. To introduce the BFO signal (since the LO is done through a two pin header) I had to uncouple the crystal and inject the BFO into the base of the former oscillator transistor. I am using a custom made for Pete Si5351 PLL's that has isolating caps on the outputs built into the board. Your may not so include a 10 NF on your output other wise you may smoke the transistor or your Si5351. Add the BFO signal at the junction of R102, C104.

Recapping my Raduino Replacement has 2 VFO's, USB/LSB and a Tune Tone. Did I mention the cool Green LCD?

The long term plan is a 6 Meter SSB transceiver using an outboard Transverter. Stay tuned and try to catch up.

Pete N6QW

Friday, November 29, 2019

The Art of the Build!

How to build a rig from N2CQR!

Pete's Replacement for the Bitx40 Raduino
Replacement with Sideband Select and Two VFO's 

Replacement for the Raduino

Raduino Replacement at Work on the Bench!

Check out N2CQR's blog at for a roadmap on how to build a rig. It literally is a "roadmap" and most importantly five years from now when that rig needs a bit of help, the docs guide you through the troubleshooting.

I find that in the past my old memory was pretty good on the recall -- but today not as good. So Bill's approach is indeed an excellent solution to the memory cell loss.

Through some good fortune, I now have a Bitx40. (Thanks Bill!) I purchased one several years ago but soon passed that on to a ham friend. The prior one was pre Raduino; but did undergo some N6QW magic, where I used an AD9850 and a 8X2 display. As usual --kind cool looking!

Ran some tests today the Raduino is inop! But thanks to an analog PTO -- the Bitx40 board is good!

As was announced on the last podcast SS#215, The Bitx40 is out of production and so now is a collector's item.

For the one I just received from Bill, there are several plans afoot (but not today as my garage is 41F finally it did get up to 55F and we ran some tests.) to initially getting it to work as stock. Subsequently I will  add some N6QW magic with dual VFO's, selectable sidebands, so you can work FT-8 and then provisions to use this with a 6 meter transverter for operation on 6 Meter SSB.

As Bill mentioned even though the kits may no longer be available one can still scratch build the Bitx40 and make the modifications I will be developing. Strap in -- a fun time.

If you are bored with your Bitx40 and would accept a $10 offer for what you have, use the email on the masthead to contact me and maybe we can make a deal. 

Pete, N6QW

Brain Quiz? How may words can you make from the word Tofurkey? eg Toke Fury. For kutey

Tuesday, November 26, 2019

What were they thinking? (This in not about politics!)

Happy Thanksgiving!

To our servicemen and servicewomen around the world may you have a wonderful day. Be safe and know that your are in our thoughts and prayers. 

My first Thanksgiving away from home was in 1963 when I was stationed on Midway Island and it was difficult not being with my family. The chow was excellent; but it was not Mom's cooking. 

Pete N6QW

Check out some of the vittles I made for Turkey Day.

Designs of Wonder Years?

I often speak of the wonder years (not the TV show) during the period of the late 1950's to 1970's. There was an explosion of new amateur radio equipment hitting the market and it was all about Single Side Band (SSB). 

Collins Radio lit the fire with the KWM-1 which was a very compact transmitter and receiver all in one box. You could operate it from the home shack as well as from your car or boat. It had a very healthy price tag. But then it was targeted to what Collins saw as an  emerging affluent market.

Soon others followed to the market with offerings far less in price (about 30% of the KWM-1) and of course in some cases less performance. Names like SWAN, National, hallicrafters, heathkit, WRL and Drake soon had slick advertising brochures hawking their SSB product offerings. Later entrants included SBE and Ten Tec with significant emphasis on solid state in the design.

I have had or have specific radios of that period from those manufacturers and I marvel at their differences in design approach.

The key thrusts from many of these manufacturers was low cost and offering multiband and medium power. No QRP stuff here. Just recently I had a chance to look at a schematic from the WRL Galaxy 300 Tri-band Transceiver. It was a relatively big box and boasted selectable sidebands (many did not) and three hundred watts of power. 

One of my biggest "bitches" about these vintage rigs aside from Collins Drake and WRL was the non linear dial scale. At the low ends of the band (CW) there was wide spacing between Tick marks. When you got to the high end of the SSB portion --you has to squint to see the marks let alone be able to tune in stations. To this day I sit dumbfounded as to why since some manufacturers did not have that as an issue.

Collins and Drake used a PTO (as did Ten Tec) whereas WRL did not; but I found something fascinating in the WRL design which I will cover in a second.

National Radio in the NCX 3 used two VFO ranges so that on 20 and 80 Meters you had a 5 MHz filter and a 9 MHz VFO range so that adding you get 20 Meters and subtracting you get 80 Meters. On 40 Meters the VFO range was at 12 MHz which then means with a single BFO Crystal you got LSB on 80 and 40 Meters but USB on 20 Meters. You had no Sideband selection! There was a band switch wafer inside the VFO box but ganged with other circuits so that appropriate other tuned circuits were put in play depending on the band. For the NCX-3, I recently had to service the band switch in the VFO. To change ranges a low cost wafer switch selected one of two tank networks to change the VFO range. Oxidation on the switch contacts caused a "warble" on the 80/20M VFO signal. After clean up the problem went away.

Imagine my surprise when I discovered that the WRL Galaxy 300, actually had two separate complete VFO's. The band switch did switch not RF circuits but simply powered ON or OFF for the corresponding VFO matching the band.

Shown above is a partial schematic of the BFO and VFO's. One half of a 6M11 (Compactron) is used as the crystal Oscillator where you have selectable sidebands. This makes it nice since you could now use this rig on 40M/80M WSPR and FT-8. But the shocker is to see another Compactron, a 6J11 which is comprised of two pentodes in one envelope. 

Initially I was puzzled by the schematic as the two circuits looked almost exactly the same --- which they are. But then the light bulb went on in that power was being supplied to each of the circuits depending on the position of the band switch. Thus two separate VFO's. Immediately I could see that by using two separate units you could optimize the components and eliminate the band switching of tank circuit components. You will also note that the lower VFO has a VFO Follower stage put there to solve two problems especially at higher frequencies -- VFO loading and developing sufficient gain levels (especially at these higher frequency ranges) to drive the follow on mixer stage. Hard to do with just one VFO that has the tank circuit switched in for other bands.

Now another OT trick is to note the diodes in both those circuits. Here a voltage forward biases the diode which makes it look like a grounded connection which then puts a small trimmer cap to ground. This technique was to account for the BFO Shift in changing sidebands so that the VFO is also shifted by an equal amount. The reason for this: 14.2 MHz is at the same dial location whether LSB or USB. The trimmer enabled precisely setting the amount of offset for either VFO.

SWAN not having this additional functionality simply scribed two cursor lines on the dial window. If you were on USB you used one line but if you were on LSB you used the other. Good old Herb Johnson -- a scribe line was cheap in comparison to building a complete 2nd VFO.

Today's discussion involved no Arduino's nor Si5351's but simply looked at "what were they thinking" and for 50 years ago -- there were some pretty impressive designer's at WRL. 

Since WRL was at Council Bluffs, Iowa and Collins was at Cedar Rapids. Is there some conspiracy theory that Collins engineers were moonlighting at WRL and thus the sophisticated design. I saw the same thing in the WRL Duo Bander (DB84) as there indeed was some slick engineering beyond what you might find in someone's garage?

There, you had your Elmer's lesson for the day.

Pete N6QW

Friday, November 22, 2019

Elmer's To All

When You Know Stuff, You Can Do Stuff!!!

Are you an Elmer?

Long standing in our hobby has been the concept of the Elmer. No, we are not talking about Elmer Fudd the cartoon character who always was ouwitted by the irascible Wabbit!

The Ham Radio  Elmer is a ham with a few solder burns on his hands; but most importantly a vast knowledge base on "How to do stuff". He was the "turn to guy or gal" when you wanted to know how to do things in amateur radio.

An Elmer knows how to do this...

[With special acknowledgement to N2CQR who shared this design on the soldersmoke blog. See Bill I still know how to read a schematic. 

This is a single JFET (J310) Regen receiver. I did add an audio amp so I could drive a speaker. What was critical is the "tickler" coil, sometimes called a variometer. 

Initially I had the tickler too close to the tuned winding -- read over coupled. Like an Alex Bell moment, the coil slipped off the main winding and fell to the bottom of the coil and suddenly it came alive. A bit of work with the hot glue gun will keep it welded to its current position. ]

The often asked questions such as how to build a dipole for 40M or how to wire a three wire electrical cord are in the wheel house of our Elmer. More complex skills like soldering without welding parts and how to test rigs were the mainstay of the amateur radio Elmer.

Today the Elmer's are dimishing in numbers as that knoweldge base no longer is the purview of a live subject matter expert; but now rests with the Internet, you tube videos and even blogs like this.

But there is a danger to this approach as the information sharing bypasses the learning so often evident of the one on one experience  such as with the student and teacher.

In an earlier blog post I took DX Engineering to task about their endless possibilities and their bold statement on the front cover of their latest catalog "We're All Elmers" and then quickly limiting that to the DX Engineering Staff. But maybe that is a point when taken to a larger ham population. Maybe many of us are indeed Elmer's!

I did receive one lengthy email in response to that email to DX Engineering and I am not certain that was an official response, since K3LR, (Tim) was on distro or that it was an inidividual response and K3LR was copied.

Firstly  I appreciate the thoughts that were shared in that email and the fact that a response was sent  to me.

Basically the response shared this individual's ham journey and that he did indeed have solder burns on his hands. He also shared that in the course of actually teaching ham radio CW courses that he ran across many hams who started with simple gear and were frustrated that they made no contacts and thus were discouraged and disappointed. 

His suggested solution was that new hams should BUY a radio such as the IC7300 ($1K) so that they would would have a good first time experience and that would negate any negative feelings. 

But he identfied and I heartily agree that many of these hams were using poor antennas and their actual station setup was marginal. Guess what? Adding a good experience IC7300 without addressing the antenna or station set up will not be any better than the situation with low cost CW transceivers. Guys it is the whole system that makes it all work. 

Another critical piece is that you have to know some things so you can do some things. Often the poor experience with the low cost low power rigs has nothing to do with the hardware. The operators often went from no license to an amateur extra without ever being on the air. Often many do not even understand basic operating skills or how their rigs should be adjusted. That adds a level of problems when your first rig is a Good Experience IC7300. Thank You ARRL!

A related problem is something I saw on a popular reflector. A ham was asking where he could purchase a pre-wired cool blue 16X2 LCD. Seems like he purchased a bare display and had to solder 16 wires so that it could plug into a board on one of the currently popular rigs from India. It seems like in the process of soldering the wires to the LCD he physically burned the circuit board. 

So instead of taking this as an opportunity to ask can someone help me to learn some soldering skills -- his ask: where can I buy one pre-wired. My first thought is imagine if he had an IC7300 and had to wire up a microphone.

It is very easy for me to bash these individuals by saying that time must be invested to learn about the hobby and gain some basic skills like learning to solder or how to build a dipole. But instead the credit card warrior mentality prevails -- just buy it.

So maybe some of us who have a few skills and have 60 years experience (not one year of experience 60 times over) should endeavor to help those who are just starting the journey. BUT I also say RTFM!

Am happy to report that IDE 1.8.5 is back working on my main computer. It was a corrupted Adafruit_GFX.h file. But as I said I did have a back up on another computer. An Elmer would know and do that as a matter of good practice.

Pete N6QW

Sunday, November 17, 2019

Why it is important to join the GQRP Club?

When you know stuff, You can do Stuff!

Yesterday to once again demonstrate that I can do stuff, I made some changes to the Arduino and Si5351 LO/BFO board and re-installed those two on the CRAP rig. Here you see it working on WSPR. Pretty Cool! Yes that is the Cool Blue 16X2 LCD.

Now on to a problem. Recently for The Paesano rig, I installed a new library to use with the 65K Color OLED. This is a universal library intended to use with all sorts of displays and one variant works with the ST-7735 type of display which is similar to the ST-7735 library used with the normal Color TFT displays I have used in the past.

Long story short, on some of the older projects I have developed using the Color TFT when you try to load them --you get an error message about pixel height. The sketches with the Color OLED's and as well as those using the LCD's are not affected. 

That could be a disaster! But since this is not my 1st Rodeo, previously I loaded IDE 1.8.5 on a separate (emergency) Windows 10 computer along with all of the sketches prior to the Color OLED foray. So I can still load the old sketches but not on the same computer.

I am still scratching my head over this.

Pete N6QW


Why Join the GQRP Club?

The "WHY", if all goes per plan, is that in December 2019, details of a new SSB Transceiver from N6QW will be published in the GQRP Club SPRAT. 

If you are not a GQRP Club member then you are WRONG!!!!

The new Rig  called "The Paesano", meaning Buddy,  is a 20 Meter SSB Transceiver featuring Dual VFO's and a 5 watt output. The 2nd VFO boots up on FT-8. The long form title is ..

The Paesano - A Left Coast SSB Transceiver.

Info will be provided for either 20 Meter or 40 Meter Operation. Shown above is the code for 40 Meters.

Basically, N6QW, the Ham Genius, has taken the Perigrino featured in SPRAT Issue #179, and with a bit of his usual magic made it into The Paesano.

A 9 MHz commercial INRAD filter and a couple of NE602's and you are in business.

If you are not a GQRP Club Member you will miss out -- you best get cracking!

Pete, N6QW

I am surprised no one has said...

"Russia if you are listening, if you have it, then it is time to publish a you tube video of the Sondland/emperor call of July 26th, 2019."

Friday, November 15, 2019

ZL2BMI Challenge Rig!

Let the Impeachment begin!

Finally the emperor (with a very small e) is facing impeachment! 

The case:  Bribery for Personal Gain!

Wow, who would have thought that the "stable genius" would end up at the end of an impeachment hearing? 

Stone found guilty … only a matter of time.

The emperor's "dream team" that were found guilty. He only surrounds himself with the very best people.

  1. Papdopoulus
  2. Manafort
  3. Gates
  4. Flynn
  5. Cohen
  6. Stone

The Whaddon Mk VII - Paraset Clandestine Radio

What is a Paraset? No I didn't say parasite but Paraset!  Bottom Line the Paraset was a clandestine radio set built in England...