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. 

SPRAT, the FETer, DLR headphones, and recent QSOs on the ET-2

Yesterday we had QSO #13 on the ET-2.  This was with Jim W1PID.  In an earlier contact Jim told me I had some chirp.  I fiddled with the coupling cap and the bias pot and am now T9!  These days, chirp is an endearing, nostalgic problem to have.  Thanks for the report and QSOs Jim! 

Contact #9 was with Fred K9SO.  He is in Wisconsin and QRZ.com put our distance at 633 miles.  That is our DX record so far.  Not bad for 92 milliwatts to a dipole on 40 meters. 

Most of my contacts come as a result of pleas for assistance on DX Summit or the SKCC Sked page.   But I did make one "random" contact: Contact #6 with N2VGA.  He just heard my CQ and gave me a call.  FB. 

I checked to see if OM Glen Yingling W2UW -- the guy who started all this with his ET-1 -- is still around.  He became a silent key in 2012.  But his ideas live on... 

SPRAT 137 (Winter 2008/09) has a great article by QRP hero G3XBM.  Roger built a version of the ET-1.  His was for 80 meters and he called it the FETer.   FB.   I was struck by his estimate of the sensitivity of the ET-1 receiver: -100 dbm.   I measured the N0WVA receiver (the one that I am using) has having a minimum discernible signal of -93 dbm.  Pretty close.  We may be at the limit of what you can expect from a single transistor receiver. 

SPRAT 137 had something else that really resonated with me.  G3YVF had an article on a minimalist rig using only one 6V6 tube.  Geoff opened the article with this warning "Don't try this unless you have a set of balanced armature type DLR 'phones as they are really sensitive."  I have a collection of old headphones that I picked up at hamfests in London years ago.  When building the ET-2, I checked all the old phones for sensitivity.  A set marked DLR was the most sensitive.  So Geoff's observation had been independently confirmed.   QRP Quarterly had an article comparing the sensitivities of old headphones -- we should dig that article up.   

SPRAT #137 is a reminder of what a great resource SPRAT -- The Journal of the GQRP Club -- really is.  As we say on SolderSmoke, if you are not a SPRAT subscriber you are just wrong!  Here is how to join GQRP and subscribe to SPRAT: http://www.gqrp.com/join.htm

The ET-2 with Callsign Tattoos

Slots are still available! 

Get your callsign on the ET-2!

This rig will probably soon turn into wall art here at SolderSmoke HQ.  With this in mind I have started writing on the wooden base of the rig the callsigns of all stations worked. So far we have 10.   There is space for more.  

Frequency is 7038.6 kHz.    I usually try for contacts around 1430 UTC (0930 Eastern) and again at around 2130 UTC (1630 Eastern).  I post messages asking (pleading!) for assistance on the DX Summit site and on the SKCC Sked board.  

If you are within reasonable range for a signal in the 100 milliwatt range (antenna is either 40 meter NVIS dipole or a doublet) please keep an eye on the DX Summit and/or SKCC sites and maybe try to have a contact.  

Background on the rig here: 

https://soldersmoke.blogspot.com/2019/10/more-on-et-2-better-pictures-and-more.html

Contact #10 with the ET-2 -- Perry K9NZ

Perry K9NZ was contact #10 with my ET-2 QRPp rig.   I found the above on his QRZ page.  Beautiful sentiments.  Most of us have similar stories, and similar feelings about ham radio. FB Perry.  

For All You Guys Who DON'T Use the Proper Fuse Value

Pete has been trying to talk sense on this issue for a long time, but some folks just won't listen. 

You need to have a reverse polarity protection circuit in your rigs AND you need to carefully determine fuse size needed for normal operation.  If your final transistors for some reason start pulling more than the normal amount of current, the fuse will blow before your PA transistors release their smoke.