Paul VK3HN's Video on Scratch-Building and SOTA

It was great to get a comment from Paul VK3HN -- this led to a re-establishment of contact.  Apparently Google knows who I have been e-mailing, so this great video appeared on my YouTube screen.  Thanks Google! 

-- Great to hear Paul's shout out to Pete Juliano N6QW, and Pete's concept of noodling. 

-- Paul's emphasis on testing each stage independently is really important. 

-- Wow, ferric chloride!  It is great to see someone doing this (instead of just sending Gerber files to China). 

-- Books.  This reminds me that I have to get Drew Diamond's books. 

-- Paul's comment on the usefulness of a general coverage receiver.  Right on target Paul.  

-- On the test gear, we can now add the TinySA Ultra.  And you don't have to win the Lotto! 

-- Finally, Paul is absolutely right on the need to constantly update and publish changes to schematics. I am guilty of not doing this. (I hang my head in shame.)   This became a problem in our simple High-School receiver project -- I would make changes to circuits and fail to communicate these changes to Dean KK4DAS.  Paul's method would have solved this problem.  

-- Thanks Paul! 

Nick's "Shelf-17" Al Fresco Homebrew Transceiver -- Frank Jones Would Approve!

This is a really wonderful video from Nick M0NTV.  

Some reactions:

 

-- Wow, a real celebration of Al Fresco!  And of the wooden chassis -- Frank Jones would be so pleased. 

-- Nick's description of the tales of woe caused by metal boxes is right on the mark, as is his description of the benefits of leaving the circuitry visible.  He's right -- this is an art and science kind of thing. 

-- That's a shelf, but it is FAR from being a shelf of shame! 

-- I am jealous of the S-meter.  I may need to include one of those in future rigs. 

-- Great to hear the shout outs to VK3HN, ZL2CTM, and N6QW -- we are are indeed the IBEW! 

-- I think we can see the N6QW influence in Nick's decision to use a steerable filter/IF amp board.  FB. 

-- I liked hearing Helio PV8AL in Boa Vista.   When I was building simple Direct Conversion receivers for 40 meters, I knew that I had it right when I could hear Helio's roosters in the morning! 

Be sure to watch this video, and to subscribe to Nicks Channel: https://www.youtube.com/c/M0NTVHomebrewing

He has done many other videos providing more details on the various stages that make up this rig. 

I hope to work Nick on 17 HB2HB soon. 

Thanks Nick! 

VK3HN's Amazing Summit Prowler 9 Homebrew Transceiver - A Masterpiece of Miniaturization (VIDEO)

I was wondering what Paul VK3HN was up to. Now we know: the Summit Prowler 9 transceiver. 

This is yet another amazing rig by Paul, with GREAT documentation.   

I was impressed by those bandpass filters.  I will try to do something similarly robust on my 17/12 rig. 

Paul's miniaturization of this rig is really astonishing.  I would go nuts trying to keep it this small. I just couldn't do it. 

Look closely at the boards he uses.  They look like printed circuit boards, but with all the components and all the soldering on one side.  This is very smart -- this makes it easier to troubleshoot and to change components.  

I was glad to see at least one NE-602 in there.  FB. 

The video is above.  Check out Paul's blog for more info: 

https://vk3hn.wordpress.com/2021/02/27/sp-9-a-compact-five-band-ssb-cw-qrp-transceiver/ 

Thanks Paul!

Peter Parker VK3YE Inducted Into QRP Hall of Fame

Wow, I was really pleased to learn that Peter Parker VK3YE was a 2021 inductee into the QRP Hall of Fame.  

This is a richly deserved honor.   Peter Parker  has been making extraordinary contributions to QRP and homebrewing for many years.  I remember reaching out to him when I was just getting started with homebrew phone gear.  I considered him a guru of DSB.  He helped me a lot.  Peter Parker was interviewed on the SolderSmoke podcast in 2013: 

https://soldersmoke.blogspot.com/2013/11/soldersmoke-podcast-156-special.html

Peter has published many books and has produced many YouTube videos.  He hosts an annual QRP gathering in his beloved home-town of Melbourne Australia that gets attention from solder-melters around the world.  

Three cheers for Peter Parker!  

Congratulations Peter! 

VK3YE's Web Site: https://vk3ye.com/

VK3YE's QRZ.com page:   https://www.qrz.com/db/VK3YE 

Thanks to VK3HN for alerting me to this. 

Adding Automatic Gain Control to the Termination Insensitive Amplifier

 

Earlier this month Paul VK3HN had a very interesting blog post about adding Automatic Gain Control to Termination Insensitive Amplifiers (TIAs).  

Termination Insensitivity is especially important in bidirectional rigs.  The shape of the crystal filter bandpass response is very dependent on the impedances presented at both ends of the filter.  In bidirectional rigs you are changing the signal path direction through the filter when you go from transmit to receive.  If the amplifiers at either end of the filter have impedances that vary depending on what is on the input or output of either stage, you will have great difficulty keeping the bandpass identical as you move from transmit to receive.  Termination Insensitive Amplifiers let you do just that -- they stay at one fixed input or output impedance (usually 50 ohms) independent of what is attached to the other end of the amplifier circuit.  This greatly simplifies impedance matching at the ends of the crystal filter. 

When I started building BITX rigs, I asked Farhan about the impedance matching problem.  He advised me to use TIAs on both ends of the filter and pointed me to a great 2009 article by Wes Hayward and Bob Kopski.  Using the information from that article, I built my DIGI-TIA transceiver, and I have used TIAs in almost all of the rigs I have built since that project.   

In his August 2021 blog post, Paul wanted to add Automatic Gain Control to the TIAs. He came up with a way to do this, but we worried that his circuit would have an impact on the impedance of the amplifiers. 

Yesterday, Wes Hayward W7ZOI posted on his web site a TIA circuit that lets us do it all:  Termination Insensitivity with Automatic Gain Control: 

http://w7zoi.net/tia+agc.pdf

I now find myself tempted to rebuild one of the TIA stages in my Mythbuster transceiver, adding the AGC circuitry from Wes's design. 

Thanks to Paul VK3HN for the blog post on this subject. And thanks to Wes Hayward for the TIA AGC design.  It is a real privilege to have direct input from Wes on questions like this. 

VK3HN on Scratch Building (Video)

Lots of wisdom and good info in Paul Taylor's presentation.

Paul's comment on the impact of abundant LiPo power in the field -- we no longer have to scrimp and optimize power consumption -- was very interesting.   

And thanks for the nice mentions of the SolderSmoke podcast. 

Thanks Paul!

https://vimeo.com/showcase/8253187?page=5

VK3HN's Homebrew 30 Meter SST QRP Transceiver

It turns out that many people homebrewed SST rigs.  Here is Paul VK3HN's version.  Really nice. 

https://vk3hn.wordpress.com/2016/12/27/summit-prowler-two-a-scratch-built-30m-cw-transceiver-wilderness-sst-for-sota/

HRDX Interviews Paul Taylor VK3HN

Wow, Paul Taylor, VK3HN is working on homebrew rig #11.  FB.  

This interview was quite thought-provoking. 

-- I agree with Paul about the importance of not being dogmatic about 

always staying under 5 watts.  It sounds like Paul is having fun with his 

100 watt SOTA project. 

-- It was great  to hear that Leon VK2DOB is still active in ham radio and running a QRP company in VK.  FB.  An article by Leon on CMOS mixers in the summer 1999 issue of SPRAT played a key role in my understanding how switching mixers really work.  I put Leon's diagram in my book SolderSmoke -- Global Adventures in Wireless Electronics. 

-- On blowing up the finals in simple HB gear.  The first real transmitter that I built was the VXO-controlled 6 watter from QRP Classics by the ARRL.  It had a 36 volt Zener diode across the collectors of the final.  This was to prevent the kind of final destruction Paul suffered up on that summit:  "D2 is used to clamp the collector voltage waveform to protect the output transistors if the transmitter is operated into an open circuit or high SWR antenna system."  Maybe we should revive the use of that simple SWR protection circuit, especially for SOTA rigs.