The "Fish Soup 10" Homebrew QRP CW Transceiver

The box with the two grey knobs on the left is the Herring Aid 5, the receiver that took me 38 years to complete. The box on the right is a VFO I originally built for my first BITX40Module -- it started out around 4 Mhz but I pulled turns off the coil until it was in the 40M CW band.  The Altoids in near center has the buffers -- a 40673 MOSFET and a 2n3904 BJT. The box in the back holds the Tuna Tin 2.  There the oscillator has been reconfigured as an amp.  A relay switches the output from the buffers between the receiver and the transmitter.  That big switch in the center switches the antenna and the 12 V for T/R.  The circular black thing is piezo buzzer used for CW sidetone -- I have it glued to the board upside down to keep the volume down. 

The whole thing is mounted on a kitchen cutting board.  A breadboard! 

The most difficult part of all this was getting the needed 800 Hz drop in TX freq on transmit.  You need to do this with a rig like this or else you won't be in the other fellow's passband.  I did a lot of cut and try -- in the end I put a 5 pf cap across the coupling cap from VFO to buffer.  This 5 pf cap switches in on transmit via a small relay.   It works.  I just spoke to N8AFT out in Columbus, Ohio and I was in his passband.  

So five transistors in the receiver, two in the transmitter and three in the VFO/Buffer. So it is the  Fish Soup 10.  

It puts out about half a watt.  On CW.   I am feeling virtuous and vaguely superior. I've made several more contacts.  It all works very well and is a lot of fun. 

Feedback on QSOs -- Listeners are Listening

On opposite coasts and with rigs at opposite ends of the technology spectrum, Pete and I have been putting new homebrew rigs on the air.  I'm working on a QRPp transceiver using 10 transistors.  Pete is working on an SDR rig that must use, what?,  thousands or millions of transistors.  

We've both been getting nice feedback, often from SolderSmoke podcast listeners.  Above you can see my 8 July notes on a contact with K3QP.   I was running about 1/2 watt, crystal control, from the Fish Soup 7 combo rig. 

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In an earlier post I mentioned Pete's success in working coast-to-coast on 40 SSB with his homebrew SDR RADIG.  Turns out that someone in St. Louis heard the contact: 

From: Steve 
Sent: Saturday, July 13, 2019 6:16 PM
To: Pete
Subject: Friday QSO

Hi Pete

Heard your QSO to Virginia last evening. Conditions were rough but could hear good enough. I’m located west of St Louis and was outside portable with KX2 and wires tossed in a couple trees. Tried to tail end but of course my signal was not good for you in California.

I really am amazed at the work you put into your projects, websites, and podcast. Can’t thank you enough. Please keep it up.

I worked at McAir in St Louis and spent many hours in the MDEC building St Charles. That was in the late 80s.

Steve

K0SAM

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Finally, earlier in July I had a contact with K1PUG.   Someone north of the border heard us: 

On Sunday, July 7, 2019, 01:17:47 PM EDT, Dave  wrote:

I heard your QSO with Hank K1PUG at my cottage in Canada (FN15ac) this morning. I wondered why you were so faint (since I had been getting good reports with 5W into your area) but when I read this morning’s entry in SolderSmoke, and saw you were 750mW, all became clear.

73,

Dave KM6CPF / VA3NIA

N6QW goes Coast-to-Coast with HB SDR RADIG

From: Frank
Sent: Saturday, July 13, 2019 6:55 AM
To: Pete Juliano
Subject: Re: 40M QSO with N6QW

GM Pete 

Yes fun QSO last night. You did have a great signal and excellent audio from your HB SDR .

Lots of great info on your website. 

I am enjoying my wire beams.  I have two five element wire beams mounted end to end beaming Europe that I get on that direction a lot. I'm planning to get an Array Solutions StackMatch soon that will help my signal even more.

Keep up the good work with the SDR rigs Pete.

I look forward to our next QSO. 

73

Frank WA3RSL 

On Jul 13, 2019 9:42 AM, "Pete Juliano" wrote: 

Hi Frank,

Last night was the first coast to coast QSO with my homebrew SDR Transceiver. Thanks for the signal report and the comments on the signal.

This has been a fun project and my main band of operation these days is 40M. I have the capability to put the SDR on 75 as well as 20M. The second prototype (now in work) will use plug in coils for those two bands. It is simply amazing what can be done with a $35  computer.

I have several websites but one has been dedicated to SDR and there is more documentation about the SDR project.

http://www.n6qwradiogenius.us

Thanks again and at times you hit 15/9. Nice radio and nice antennas.

73’s

Pete N6QW

Chinese Micro-Satellite Photographs Eclipse -- FROM THE MOON

Back in October 2018 I posted about this Chinese satellite: 

https://soldersmoke.blogspot.com/2018/10/chinese-amateur-satellites-orbiting.html 

From:https://www.newsnation.in/science-news/chinas-lunar-orbiter-captures-epic-images-of-earth-during-solar-eclipse-article-229818.html  :

According to report by Xinhua, a microsatellite developed by the Harbin Institute of Technology in northeast China's Heilongjiang Province, which is now orbiting the moon, captured mesmerizing photos of Earth during the solar eclipse in the early hours of Wednesday (Beijing time).

It is to be noted that the microsatellite, weighing 47 kg and named Longjiang-2, was sent into space on May 21 last year, along with the Chang'e-4 lunar probe's relay satellite dubbed as "Queqiao" and entered lunar orbit four days later.

According to the research team from the Harbin Institute of Technology, the microsatellite carries a mini CMOS camera that only weighs 20 grams, which makes it easy to operate, and it can take pictures at short intervals.

“Since the camera uses an automatic exposure mode, the camera's field of vision must contain a certain area of the moon to realize correct exposure. When the recent total solar eclipse occurred, the orbiter was flying over the far side of the moon. In the few minutes before and after the moon blocked the earth, all the conditions were right to take the pictures,” Xinhua further quoted the team as saying.

According to the team, to avoid becoming space rubbish, the microsatellite will be controlled to crash into the moon after it stops operation at the end of July.

As per Xinhua, the team cooperated with amateur radio operators in Spain and Germany in taking and receiving the photos. Nearly two pictures taken by the microsatellite during the solar eclipse were sent back to Earth on Wednesday. 

The Fish Soup 7 QRP Rig -- On the Air on 40 Meters (video)

I don't know why, but this weekend I got the urge to get on the air with a very low power homebrew QRP rig.   I reached for my Tuna Tin 2 -- Herring Aid 5 combo.  I call it the Fish Soup 7 (seven transistors in total). 

I first tried to turn this rig into a transceiver by taking the VFO signal from the receiver (it is direct conversion) and using it to excite the Tuna Tin 2, but it just didn't work out.  The oscillator in the Herring Air 5 is very bare bones -- no buffering and an LC circuit that is mostly L (10 uH).  It became very difficult to get a stable amount of CW offset.  So I went back to crystal control for the transmitter.  I did replace the 5K tuning pot in the RX with a 10k 10 turn pot (thanks to W8NSA).  Tuning is now very smooth.  I used my old UK freq counter to monitor my receive freq. (Thanks to Tony Fishpool G4WIF-- back in 2009 he sent me the CMOS chip that brought this counter back to life.) 

I was putting out about 750 milliwatts.  

I had a very quick contest-like contact with K2D -- one of the "13 Colony" stations.  Then a longer chat with Hank K1PUG (see video above).  

I had lost my 7050 crystal, but this morning it re-appeared.  TRGHS. 

As you can see in the video I am using the beautiful VU3XVR  key that Farhan brought me from India. 

This was fun.   I may try to put a VFO of some sort into the TT2, just to get more agility.  But I want to keep things simple.  

Look for me on 7050.  

Homebrew RF Design Contest -- Win $3,000!

https://www.nxp.com/products/rf/rf-power/homebrew-rf-design-challenge-2019:Homebrew-RF-Design-Challenge-PG

Building Spark-Gap Transmitters -- And a Very Cool Coherer (video)

The creators of "Plasma" and "Blueprint" YouTube channels have collaborated on this very interesting video about spark-gap radio transmitters and receivers. Really nice work.  Especially impressive was the coherer build by Blueprint.  I detect the spirit of Nikola Tesla in his lab!