VK3HN's Inspirational AM Receiver (video)

I'm always delighted when I check the SolderSmoke blog and YouTube list (right hand column of the blog) and find a new post from Paul VK3HN.  And this morning's post is especially good. 

Paul has built an AM receiver. Above you can see his video.  Here is his blog post with details: 
https://vk3hn.wordpress.com/2019/12/06/8-band-superhet-am-receiver/

This is the kind of blog post that makes you want to heat up the soldering iron and start searching through the junk box.  I'm thinking about putting Paul's 6 kHz filter in my 40 meter HRO-ish receiver.  And I may make use of his AM detector circuit.  And maybe I can put that same receiver on 75 and 160... And then there are the SW broadcast bands... See what I mean?  

Thanks Paul.  73  

My QRPp Signal Arrived in Utah -- 100 mW, 1950 miles, 26 db Above the Noise!

So yesterday morning I was calling CQ on 40 meters with my ET2 two-transistor 100 mW rig.  Later, I took a look at the Reverse Beacon Network (RBN).  Among the East Coast skimmer stations that regularly pick me up I saw an  outlier:   WA7LNW in Utah.  He's 1950 miles from me. And the RBN reported that his receiver had me at 26 db above the noise.  

Here is a screen shot of the RBN report.  Note the time: 1234 UTC.  Around sunrise here -- so gray line conditions.   

But the really BIG factor explaining that 26db s/n ratio is WA7LNW's location: 

"Realtime spots are being received at this location and uploaded to the Reverse Beacon Network."

"CW Skimmer antenna is located on cliff edge overlooking the Virgin River Valley, 1,200 ft. below."

We reported on the WA7LNW RBN station back in 2013:  https://soldersmoke.blogspot.com/2013/03/edgy-skimmer-antenna.html

Check out Jack's QRZ.com page: 

https://www.qrz.com/db/WA7LNW

RBN is an important resource for QRPers and homebrewers.  Three cheers for Jack and all the skimmer stations.  Thank you all.  

ET-2 Contact #18 W4FOA -- RANDOM, UNSCHEDULED, AND NOT SPOTTED (Video)

On December 1, 2019,  my 100 milliwatt signal flew more than 500 miles to reach Tony W4FOA in Chickamauga, Georgia. And -- icing on the cake -- this was a random contact.   Tony just heard my CQ on 7038 kHz -- he had not been alerted to my CQ by any spotting site or by the SKCC Sked page.  I made a quick video of my side of the contact (above). 

In a follow-up e-mail Tony explained how my CQ sounded to him: 

"I was just listening on the 40 meter band and having been a QRP'er for 50+ years, I tend to notice the weaker stations, thus explains my calling you.  Also, your signal had that little "sound" of "yesteryear" when signals were not all pure, hi.  Had it not been for the QSB and QRN we could have had a long chat despite the weak signal from your QRPp.  Over the years I have QRP DXCC, 2 way QRPARCI WAS, and my best DX was two QSO's with 2 different VK7 stations on 40 when I was running 1 watt.  I've had a lot of different QRP rigs and still have some home brew stuff plus a couple of HW8s, HW9, Elecraft K2, etc..."  

From Tony's QRZ.com page, we learn more about his ham radio activities (note his homebrew rigs and his obvious affection for the Drake 2B and 2BQ) 

First licensed as WN4FOA in April 1954. Other calls held include EL2AD, 7Q7AA, PY1ZBA. Prefer to work CW but I do work some SSB, primarily DX-related. Enjoy chasing DX on all HF bands. Have 9BDXCC and I now have worked and confirmed all of the current DXCC countries . I enjoy QRP operation and currently use an Elecraft K2 (#2213),Ameco AC-1, Kenwood TS-130V SW-40, DC-40, HW-8 (2), Heathkit HW-9 Deluxe (WARC) PSA-9 HFT-9B SP-99 HM-9 HD-420 VLF, MFJ 40T and MFJ 40V VFO,  and a homebrew 6AG7/6L6 or a 6C4/5763  etc. I also enjoy operating boatanchor gear which includes a Johnson Viking Adventurer, Viking Challenger,  an Eico 720 and an Eico 723 with a HG-10B VFO and a Heath AT-1 and a Drake 2NT. Recently added a neat Lysco 600 transmitter and a Knight Kit T-60, Johnson Viking II, and a Ten Tec 544.  Boatanchor receivers include a Hallicrafters SX-100, SX-110, SX-71, Drake R4C and the incredible Drake 2B/2BQ combo. Recently added a Kenwood TS-830S, VFO-240, AT-230 and SP-230.

Tony W4FOA

Thanks a lot Tony.  73

ET-2 Contact #16 -- Pete, KD2OMV, Builder of a 6T9er (with video)

Yesterday I had my  first contact using the ET-2's improved receiver.  I had watched the video of N0WVA's receiver and I realized that more sensitivity was possible.  So I tried to replicate his LC ratio. I think that helped a lot.  Today I posted a plea for help on the SKCC Sked page and then called CQ on 40.  I was answered by Pete, KD2OMV who was so loud that I had to take the headphones off my ears!  He was booming in, all the way from upstate New York. The receiver was running off a somewhat depleted 9 volt battery.   I made a quick video (above).  I'm just holding the I-phone up to the headphone, while also trying to copy the incoming CW. 

This was a really great contact.  Pete has a wonderful knack story.   He was licensed as a kid but never made a contact.  As an adult he found his old box of parts for a 6T9er in his parents house. So he builds it and uses the homebrew rig to make his first ham radio contact.  FB Pete. Thanks for the contact OM.  I wrote your call on the ET-2. 

Pete KD2OMV

Mr. Carlson's Analog Panadaptor -- "Like a digital waterfall, but fun!"

We've been talking about Panadaptors -- especially about NON-DIGITAL Panadaptors.  Kind of like waterfalls without the digital water.  A while back I rigged up a very crude non-SDR panadaptor using my Feeltech sign generator, my Rigol 'scope and a DITX40.   Here it is: 
https://soldersmoke.blogspot.com/2019/05/diy-waterfall-quick-and-easy-panadaptor.html

In the above video Mr. Carlson looks at the old PCA-2T-200 Panadaptor.   The first five minutes give a really good overview of how the device operates. At around the 5 minute mark Mr. Carlson notes that modern digital receivers have SDR based waterfall displays, but noted (correctly!) that "that's no fun!"   Thank you Mr. Carlson. 

Follow-Up on Scratch-built BITX17 -- Board Map and Video

In my last post I put up a time lapse GIF of my BITX 17 build from about six years ago.  Above you can see my drawing explaining what each of the stages that you see popping up on the board were.  More diagrams here: 
https://soldersmoke.blogspot.com/2013/11/bitx-build-update-19-layout-vxo-bal-mod.html
And a lot more info on this build are available on this blog.  Just use the search box for build updates (but be aware that this search will also bring up updates on later projects). 

Above is a slightly out-of-focus video tour of the board. 

I'm posting this stuff partly in reaction to the news that the BITX 40 module is no longer for sale.  I hope these posts will serve as a reminder that it is quite possible to homebrew from scratch your own BITX transceiver.  This is a fun and rewarding project.  Three cheers for Farhan! 

How A Homebrew BITX Comes Together

This is a bit of a blast from the past.  When I was building my BITX17 I paused after placing each stage on the board and took a picture.  Here is the animated GIF.  

SolderSmoke Podcast #215 Regen Madness, KWM-4, Paesano, Mailbag

Latest N2CQR version of N0WVA's Regen

SolderSmoke Podcast #215 is available. 

25 November 2019

http://soldersmoke.com/soldersmoke215.mp3

Happy Thanksgiving! 
Transit of Mercury
Book Reviews 

Bill's Minimalist Adventures:
-- 15 Contacts with the ET-2 
-- Ethical issues:  Is spotting yourself OK?  OK to use TWO FETs? 
-- Using Reverse Beacon Network
-- How to keep receiver on the right frequency
-- N0WVA's receiver sounded better, so I built a second N0WVA receiver
-- Regens reach back to Edwin Howard Armstrong's 1912-1923 breakthrough
-- Regens are fun, but they are not good projects for new builders. 

-- Pull out those Michigan Mighty Mites and listen for yourself via on-line SDR receivers.

Pete's Projects: 
"WHEN YOU KNOW STUFF YOU CAN DO STUFF!"
-- Left Coast SSB -- "The Paesano" -- To be featured in December 2019 SPRAT. 
-- Pete's KWM-4 on The Collins Collectors Net
-- Pete builds an N0WVA regen -- just in time for Sweepstakes CW Saturday! 
-- Arduino IDE Library trouble
-- uBITX 6.0? Fake News? 

No more BITX40 Modules.  Long Live BITX40 HOMEBREW! 

BITX-101.   Intriguing but on second thought, no.   

MAILBAG

Steve Silverman:  Lexicon:  "Audible Modes." 
Felipe CU2BD   Old buddy from the Azores
Michael Rainey AA1TJ:  Come back Mike!  The ionosphere needs you! 
Jack Welch  AI4SV is in 5G land  (Cyprus, not the cell phone thing). 
Walter AC4IM is at the San Vito Solar Observatory in Italy.  DO SOMETHING WALTER! 
Kostas SV3ORA has an amazing homebrew web site.  Thanks Kostas! 
Mike KC6SAX -- How to deal with the frustration of HB projects that don't work. 
Paul KL7FLR -- Pete is 7 Hz high. 
Keith W3ISZ  sent his photo of the Transit of Mercury.  

PLEASE USE THE AMAZON SEARCH BOX ON THE SOLDERSMOKE BLOG PAGE WHEN DOING YOUR CHRISTMAS SHOPPING. 

PLEASE SUBSCRIBE TO THE SOLDERSMOKE CHANNEL ON YOUTUBE. 

N2CQR's ET-2 with callsign Tattoos 

Notes and Video on Doug N0WVA's Amazing Single Transistor Regenerative Receiver

When I had trouble getting the regen receiver in W2UW's ET-1 circuit to work, I turned to the internet and -- through AA7EE's site -- found the circuit of Doug N0WVA.   This circuit has completely changed my attitude toward regen receivers.   I have been exchanging e-mails with Doug -- below is a compilation of the info and regen-wisdom that he has shared.  More to follow... Thanks Doug. 

From Doug N0WVA: 

I came up with the diode after exploring ways to ditch the source r/c combo. The thinking was the closer I could get the source to ground the less voltage/capacitance fluctuations the gate would see.  Also I hated seeing everyone using .01 bypass to avoid audio oscillations and also losing audio gain. 

 The green LED works good but even better is directly grounding the source. Then feed a small negative bias through the gate leak resistor , adjustable via a potentiometer.  

On video, the audio is taken straight from the radio shack headphones that are connected to the audio transformer. The headphones are held directly to the phones case ( no hole for the microphone seen on the phone)  

The variometer is  made with I think a 1.25 inch pill bottle and the tickler inside is around an inch in diameter pill bottle. I used a pharmaceutical syringe's outside tube for a shaft. The tickler form has a couple holes cut for the shaft to pass through, it is a friction fit, more like slits cut and the rod pushed through. I used the soldering iron to melt round holes on the actual outside coil form for the shaft to turn on. On the back of the shaft is a small screw that goes through the outside coil form and screws into the syringe center hole that holds it in place. The tickler is one turn, I think, and routed through the inside of the shaft via small holes melted with the soldering iron.

A couple tweeks to mention is instead of a resistor in the gate, use a choke for less noise, makes a big difference, especially if you listen to AM.  Also I have been using a gimmick for the gate cap.  Just maybe a #36 enamel wire wrapped around  the hot tank lead 5 or 6 times and then I remove turns till the thing stops oscillating, then add a turn. This helps cut down even more on strong signal pulling. 

I have always been on a quest for more performance out of the least parts. This design was about as far as it could go, I think....

I have never done any real sensitivity tests on the regen, so you have gone farther than me already. One thing was noticed though is the gate resistor does add a lot of noise, especially noticeable just under oscillation in AM detection mode.  So I took a one meg 1/4 watt resistor and wound as many turns of #38 wire on as I could, probably around 80 turns, then subbed it out for the gate leak.  This dramatically improved the noise level just under oscillation. This was with a simple antenna band noise test. I think it also improved the noise under oscillating conditions. 

Adding extra antenna coupling will probably help a lot, but, there is a point where we start getting too much strong signal pulling.  The strong external bias battery trick will also improve this, although at the cost of extra parts.

Transit of Mercury, 11 November 2019, and a Transit of Venus and Some Sunspots from 2012

Above:  Transit of Mercury, November 11, 2019 as I saw it from Northern Virginia using a 4.5 inch reflector with image projected onto a white paper.  Elisa took the picture with her I-phone.  Arrow shows Mercury.  I almost missed it -- Billy texted from college to remind me of the big event. 

Above:  Transit of Venus June 6, 2012 as seen from Northern Virginia.  Billy (age 13) took the picture with his I-phone 4.  Venus is much bigger, much closer and much easier to see.  Near the bottom edge of the solar disc. 

  

Above;  Billy on November 12, 2011 with the 4.5 inch Tasco Reflector that was used on BOTH the Venus and Mercury transits (we projected the image on paper). On this day we were using our newfound solar photography expertise to take a picture of sunspots (our picture below). 

Ah, those were the days!  Many spots back then.  None now. 

Listen to the ET-2's Minimalist Regen Receiver

I'm guessing that most of you have never listened to a regen receiver that uses only one transistor.  So in these videos I've tried to capture the experience.  The audio that you hear from the receiver is from a small I-phone microphone taped to the one of the headphones on my DLR WWII headphones.  So you are hearing it just as I hear it -- with no additional amplification. 

Here is N0WVA's schematic.  When I tune the "regeneration" control I am turning the knob on the variometer.  The broad or "bandset" tuning control is essentially N0WVA's 25 pf cap.  My fine tuning control (the one that I use the most in the video) is the equivalent of the smaller cap in parallel with the larger tuning cap. 

I had trouble shooting the video for this post -- taping the mic to the headphone turned out to be a bit difficult.  So I ended up with a few extra (and imperfect) videos.  I include them here for anyone who might want to listen some more to a single transistor regen.  (I have a few more -- let me know if you'd like to see them!)



In the next one, at the end I throw the switch to transmit allowing you to hear what "sidetone" sounds like on the ET-2

SV3ORA's Amazing Homebrew Web Site

Kostas Giannopoulos has  a lot of really great homebrew information on his QRP web site.  It is reminiscent of the JF1OZL site. Check it out:  http://www.qrp.gr/index.htm 

For an example that his apropos of recent ET-2 discussions, Kostas has an extensive page with  many, many versions of his hyper-minimalist rig:  

Link to this project: http://qrp.gr/allbandtrx/

Thanks to Kostas for putting together such a great site.  And I really like the name of the site: Discrete Electronics.  FB.