SolderSmoke Podcast #249 -- Travel, Pete's 6BA6 rig, Books!, VFOs, SDR, Computers, Spectrum Analysers, Transistor Man! MAILBAG

New VFO for 15-10 Transceiver

Schematic below

SolderSmoke Podcast #249 is available:  http://soldersmoke.com/soldersmoke249.mp3

There is also a video version of this podcast: https://youtu.be/5xyaYivtOhw

Travelogue:  

HAPPY VETERANS' DAY TO PETE AND GRAYSON AND TO ALL THE OTHER VETERANS WHO ARE LISTENING. 

Trip out to San Francisco. Sticker placed on the corner of Haight and Ashbury:  See picture below.  Note other sticker.  Really Groovy! 

Cuban Cacharreo! Andy CO2AFV's Knack Story  https://soldersmoke.blogspot.com/2023/10/a-cuban-knack-story-and-pandemic-sits.html

Bill's DXCC-100.  DONE.   

Tribal Wisdom:  W1REX on HRWB https://soldersmoke.blogspot.com/2023/11/listen-to-rex-w1rex-lots-of-tribal.html

Pete's Bench:

Pete's 6BA6 rig

Pete's 6BA6 Rig

Pete Re-invents the Shirt-pocket SSB Rig

Pete's remake of the ShirtSleeve Transceiver

Pete Builds Two Computers 

Pete Adds a Second Band to his Homebrew SDR 

 

SHAMELESS COMMERCE DIVISION:  

BEZOS BUCKS ARE BACK!  PLEASE  BUY THERE! >>>>>>>>>>>>>>>>>>>>>>>

Mostly DIY RF:  Work proceeds in the Oregon Silicon Forest on P3ST kit development. Todd is confident the P3ST will be released on December 18th.Many other kits available now:  https://mostlydiyrf.com/ 

Sign up for the newsletter:  https://mostlydiyrf.com/subscribe/ 

Bill's Bench: 

Rebuild of the 15-10 VFO (for improved Dial Spread) (with yet another QF-1 capacitor) https://soldersmoke.blogspot.com/2023/10/dial-scale-linearity-spreading-out.html

Why Building for 10 meters is harder: https://soldersmoke.blogspot.com/2023/09/why-building-for-10-meters-is-harder.html

Copper Tape shielding of 15-10 rig. 

Crushing Spurs with Better Bandpass Filters (see blog post) https://soldersmoke.blogspot.com/2023/09/crushing-17-and-12-meter-spurs-with.html

Another 15-10 rig in the works... for SSSS.   Boards are accumulating... 

More problems discovered with the Herring Aid 5 Receiver . Lots of SS blog posts  Comment from Rick WD5L.  ) https://soldersmoke.blogspot.com/2023/10/a-big-error-discovered-in-1976-qst.html   Did you try to build one?  Did you succeed or did you fail?  Please let us know. 

The Basil Mahon books (blog posts) https://soldersmoke.blogspot.com/2023/11/basil-mahon-is-author-for-us-he.html

The Sunburst and Luminary book of Don Eyles (blog posts) 

The Art of Electronics by Horowitz and Hill (blog posts) 

Spectrum Analysers:  Tiny SA Ultra https://soldersmoke.blogspot.com/2023/09/the-tinysa-ultra-spectrum-analyser-video.html  and Polarad 632C-1; George WB5OYP gave me one of these spectrum analysers  (I NEED a manual! Does anyone have a manual or a schematic? )  : 

Polarad 632C-1

Stabilizing the EB63A (with Pete recommended LP filters from e-Bay. 

MAILBAG:

TRANSISTOR MAN T-SHIRTS!  Thanks to Roy WN3F! 

Todd VE7BPO on AF amplifiers.  Thanks Todd.  

Wes W7ZOI -- Always a privilege to exchange e-mail with Wes. 

E-mail from Jay Rusgrove W1VD. About the Herring Aid 5. 

E-mail from Eamon Skelton EI9GQ!  Amazing! 

HB2HB with Denny VU2DGR https://soldersmoke.blogspot.com/2023/09/hb2hb-contact-with-denny-vu2dgr.html

Nick M0NTV on diode matching for ring mixers: https://soldersmoke.blogspot.com/2023/10/does-matching-matter-diode-matching-for.html

Paul Taylor VK3HN on the new Elecraft CW rig. 

Dean KK4DAS fixed the noise in his Hallicrafters SW receiver.  A long battle, finally won. 

Dean also in contact with G3UUR. 

Ramakrishnan VU2JXN helping me set up a backup of blog on WordPress.  

Mark KA9OOI noticed that SS podcast archive appears gone.  In fact just temporarily relocated to http://soldersmoke.com/podcastarchive.html

(SS PODCAST Archive temporarily relocated to http://soldersmoke.com/podcastarchive.html) 

Andreas DL1AJG - Crystal radio video. https://soldersmoke.blogspot.com/2023/10/building-crystal-set-videos.html

George N2APB on the Herring Aid 5

Grayson KJ7UM experimenting with Varactors and Thermatrons! 

Thomas K4SWL on Mattia's DC receiver. https://soldersmoke.blogspot.com/2023/10/mattia-zamanas-amazing-direct.html

Bob Weaver of Dial Bandspread Linearity  fame.  Electron Bunker

Mike Bryce WB8VGE QRP Hall of famer -- he too couldn't get the Herring Aid 5 working. 

Kirk NT0Z wrote about the Wayback machine.  But this former ARRL staffer he also tried and failed to get the Herring Aid 5 going.  Way back when... https://soldersmoke.blogspot.com/2015/03/kirks-herring-aid-tuna-tin-and-regen.html

New 15-10 VFO with schematic

Dial Bandspread (Before)

At corner of Haight and Ashbury

W1VD's Boatanchor Receiver Tests

I've been trying to get more rigorous in my evaluation of receiver performance.   My HQ-100 is tuned to Radio Marti, and it sounds great.  But how great is it really?  And what about all the receivers and transceivers I have built?  How good are they?  

Our friend Dean KK4DAS is about to start the rehabilitation of his dad's old HQ-170A.   A search for that receiver led me to Jay Rusgrove's very interesting measurement and analysis of old tube type radios.  Jay's results appear in the links below.  More important is his very clear description of how the tests were done and what the results mean (link below). Also included is one link showing a discussion of Jay's work.  

Jay notes: 

The decision of which boat anchor receiver(s) to own is seldom based on performance alone. A combination of favored manufacturer, period of manufacture, features, collectability or even just 'looks' often rank higher on the priority list than receiver performance. Even if one were interested in performance specs much of the available information is subjective as few receivers manufactured prior to the mid 70s have undergone standardized testing. Hard data on minimum discernable signal (MDS), blocking and two-tone IMD dynamic range is interesting to some operators and important in an historical context as it shows the progression of receiver development.

Jay designed the very first real transmitter that I homebrewed (The VXO 6 Watter from QRP Classics). Jay has been mentioned many times in the SolderSmoke podcast and blog:    

Jay's results:   http://www.w1vd.com/BAreceivertest.html

Jay's methods:  http://www.w1vd.com/Receivermeasurementbasics.html

Discussion: https://www.antiqueradios.com/forums/viewtopic.php?t=96872

Some Really BIG Coils

I met W1VLF on 40 meters last week.  "VLF" was a hint.  And indeed, Paul has been experimenting in the 10 kHz range.  His antenna loading coil is seen above.
More info here: http://rescueelectronics.com/9-Kilohertz.html
Very cool that Mike was working with Jay Rusgrove, W1VD, on this project.  Jay designed the 6 watt VXO rig that was my first homebrew transmitter.

And additional VLF info here:
http://n3cxv.com/WH2XND_station_1.pdf

A New Look at BITX Carrier Suppression; N6QW IN EMRFD!

Bert, WF7I, was recently struggling to get his BITX 20 going and he asked some good questions about carrier suppression.  I realized that I hadn't really paid much attention to this.  Perhaps as a result of my long experience with DSB, I was happy as long as I was able to null out MOST of the carrier. 

I fired up the scope and took a look at the output from the BITX 2040 on 40 meters.  Here's the test setup:  Coax from the antenna terminal to a 50 ohm resistive load at the Rigol O'scope probe.  Just keying the transmitter (no mic connected),  carrier was at 980 millivolts rms or about 19 milliwatts.  I then connected an AF sig generator into the mic in connector and pumped in some 1000 Hz sine wave. Peak output was 20.7 volts rms, or about 8.6 watts.   That puts the carrier about 27 db down.  I felt I should be doing better. 

I took a look at the shape of my crystal filter and the frequency placement of my carrier oscillator.  I noticed that the carrier oscillator freq was fairly close to the bandpass portion of the crystal filter -- fairly high up the skirt, only about 9 db below the passband level.   I figured that if I just moved that carrier oscillator up around 300 Hz, I would get around 10 db of additional carrier suppression. 

Sure enough,  with the carrier moved a mere 300 Hz further away from the passband,  the residual carrier dropped to 346 millivolts rms, or about 2.4 milliwatts.    Now peak output was 20.9 volts rms, or 8.7 watts.  36 db of carrier suppression. 

I guess I could do better if I moved the carrier up another little bit, but I like the sound of it now.  I may have been able to better if I'd fiddled with the balanced modulator diodes a bit more.  But what do you guys think?  Should I worry about 2 milliwatts of residual carrier?  Heck I once ran a CW rig (W1VD' VXO 6 watter) that kept the oscillator running on key up, producing about 15 mw of "backwave." No damage was done, few noticed, no one complained.

Oh yea, is this the way to measure carrier suppression? 

----

While doing all this, I pulled out my trusty copy of EMRFD.  The index led me to the balanced modulator section on page 6.56.  There I spotted a familiar call:  W6JFR!!!  That's Pete Juliano, N6QW!  Pete is credited with a mod to the SBL-1 mixer that adds a balance control pot to the device.   Wow, actually being IN EMRFD fully confirms Pete's homebrew guru status.


Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Edgy Skimmer Antenna

For the last few days I've been hanging out on 20 meter CW, 14.050 - 14.060 MHz, using my re-built W1VD/Barbados rig.   I've had some great contacts, but almost as  much fun is watching the Reverse Beacon Network to see who is hearing my calls.   WA7LNW is one of the "skimmers" that most consistently picks up my signal.  One look at the picture above explains this.  The receive antenna for his skimmer rig IS ON THE EDGE OF THIS CLIFF!   Jack has one of those dream jobs for a radio amateur:  he works at that amazing location, testing ejection seats for jet aircraft.  More great pictures here: 

http://www.dxwatch.com/qrz/lookup.php?c=rbn/WA7LNW

Thanks for the reports Jack!

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

DeMaw's Barebones Superhet

A recent e-mail got me thinking about Doug DeMaw's Barebones Superhet.  June 1982 QST.  Mostly 40673 Dual Gate MOSFETS (this one's for you Dino!).  Barebones indeed.  Check out the schematic.

I literally blew the dust off my version and fired it up on Sunday.  It sounds really great.   I had lowered the values of the caps in the ladder filter to widen it out for phone.   Also, I see that I used LM386 instead of the op amp AF Amp prescribed by W1FB.   I notice that my version has much better audio than another version of this RX (with the op amp) that I'm using on 17 meters.  Could the difference be the LM386 vs. op amp?  There is a lot more audio with the 386, and the AF response seems wider.  

I feel the urge to put this receiver to use.  I am rehabilitating the W1VD CW transmitter that used with it during the late nineties, but I'm a phone guy now, and I feel compelled to use this RX as part of an SSB rig.  Of course, I could build a standalone SSB TX, but how about a diode switching scheme to make use of the Barebones' filter, the VXO and the BFO in a transceiver?

Here is my article on the original build of this receiver: http://www.gadgeteer.us/HBHOME.HTM

Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20

Richard's Rip-Van-Winkle Barbados Rig

Dear Bill,

Thank you for taking a few minutes to read my email. I recently found your blog and enjoyed reading the entries.  However, the most interesting and exciting article I discovered was your "Homebrew Radios in the Age of the Internet." The article reminded me of a project started 30 years ago this month and placed in a box in the attic to wait until I could return to it.
Thirty years of health care management work filled the interim.

The project is the 8P6 Hamcation rig by W1FB from QST of June and November 1982!

I searched through the cob webs in the attic and found that all the boards are completed and I even fabricated a case. The original QST's were there too! In response to a (somewhat strong) suggestion from my wife to "get a winter project going", the rig is back on my retirement work bench. Wahoo.

Progress to date has been instructive and fun. The boards are all cleaned, checked, and 95% wired together in the case and working. I attached 2 photo for your pleasure because you wrote specifically about the receiver in some blog posts.

This is where I am scratching my head. As you say in the article, "receivers are tough". I am confused and a bit frustrated about the correct procedure and sequence to correctly align the Barebones superhet. I can already hear stations and the noise level is acceptable. But I am not quite sure how to proceed in peaking up the receiver (hit a plateau?) Any suggestions for a newly retired ham now with the time to get back to the bench?

Thank you very much for your kind comments and interest in my project.

73's
Richard
WB2PEF
Cherry Valley NY

Wow, what a cool resurrection project!   I recognize both the receiver and transmitter boards.   The RX is clearly DeMaw's Barebones Superhet on a FAR Circuit board.  I am listening to one of those AS I TYPE.  Mine was put together by Dale, W4OP, and currently inhales on 17 meters.   The TX board is what became known as the VXO 6 Watter.   It was (I think) designed by W1VD, and appears in the ARRL book "QRP Classics."   This was my first really successful homebrew rig -- I built that transmitter in the Dominican Republic  in 1993.   I still have most of the board, and the 20 meter Barebones RX that I used with it.   Richard's message makes me want to put this old gear back on the air. 

I hope Richard will send us an update on his Barbados revival project.

I'm sure Doug DeMaw would be very pleased to know that his projects are still providing radio amateurs with a lot of fun and inspiration.


Our book: "SolderSmoke -- Global Adventures in Wireless Electronics" http://soldersmoke.com/book.htm Our coffee mugs, T-Shirts, bumper stickers: http://www.cafepress.com/SolderSmoke Our Book Store: http://astore.amazon.com/contracross-20