Bringing a Faulty Herring Aid 5 Receiver Into the Light -- Fixing the AF Amp Schematic Error (video)

I picked up this old homebrew receiver in March 2023 at the Vienna Wireless Society's Winterfest Hamfest.  It is a Herring Aid 5.   I was surprised to see that the builder (who was he?) got the windings on the VFO transformer right.  Later, I learned that he had also substituted MPF-102s for the original Radio Shack FETs called for in the QST article. This allowed him to overcome the PC board layout problem at Q5 (VFO).  With an MPF-102, he was able to get Q1 working by kind of shoe-horning the leads into the proper holes.  FB OM.  Whoever he was, he seemed like a really competent builder.

The Hamfest Herring Aid 5

But then I started wondering:  Did he also overcome the big problem in the audio amplifier?  You see, there is an egregious error in the QST schematic.  Between the collector of Q3 and the base of Q4 (the two AF amplifiers) they have a 10uF capacitor to ground.  That would send most of the audio to ground. This is clearly a mistake.  Not only does it not make any sense, but this cap to ground does not appear in the PC board drawing, nor in the photograph that went with the QST article.  I included this cap in my 2014 built of the Herring Aid 5, but with it, I found the receiver to be exceedingly deaf.  When I clipped that capacitor out of the circuit, my 2014 Herring Aid 5 sprang to life.  Did this hamfest Herring Aid 5 have the error capacitor?  Would it too be brought into the light by clipping one lead?  

Sadly, the erroneous third capacitor was there, and it was wired into the circuit.  The receiver worked,  but just barely.  It was very deaf.  You could not hear 40 meter band noise, and you could barely hear strong CW signals.  Builders may have thought that this was normal with such a simple receiver. 

3 10uF caps. The center one is an error.  I have clipped it out

In the video above you can see what happens when I cut the lead to the mistake capacitor.  Suddenly, you can hear band noise, and CW signals.  The receiver comes to life -- for the very first time!  

This was an error that echoed through the decades.  As far as I know there was never a published errata.  The erroneous capacitor is there in the 1977 ARRL book entitled Understanding Amateur Radio.  In 1998,  NORCAL QRP redid the Herring Aid 5.  Incredibly, THEY INCLUDED THE OFFENDING CAPACITOR in their new and improved schematic.  

NORCAL's 1998 Schematic included C14

I'm fixing up this old receiver a bit.  It was nice to have it playing 40 meter CW yesterday.  Better late than never.  

This morning I was feeling kind of guilty about paying so much attention to a receiver from 1976.  But then I opened the paper and read about the recent find of a DeLorean car.  Heck if a DeLorean from the early 80's is worthy of attention, so is a homebrew receiver from the late 1970s. 

How a Homebrewer Substituted MPF102s for the RS 2035 FETs in the Herring Aid 5 -- Who built this one? Any others out there?

The Hamfest Herring Aid 5

For background on all this, see yesterday's blog post:     https://soldersmoke.blogspot.com/2023/10/a-big-error-discovered-in-1976-qst.html

Rick WD5L noted that it was remarkable how the builder of the Herring Aid 5 that I found early in 2023 at a hamfest had built his receiver using MPF102s at Q1 and Q5.  Here is how this builder  kind of "shoe horned" MPF 102s into the QST Herring Aid 5 boards.  Pinouts for the MPF102 and the RS 2035 and the PC Board Pattern for the Herring Aid 5 appear below. 

Above  is Q5 the VFO.  You can see how he "flipped it around" to get the Drain, Gate, and source in the proper holes. You can also see how he wound the transformer for the VFO.  Looks like there was  a real battle with the soldering iron here. 

Above is Q1 (RF amp).  Again clearly an MPF 102.  But here it would not be sufficient to just flip the transistor around.  So he had to twist it and take the center lead and put it in the far right hole.  Note his markings on the board.  Looks like he made another hole for the MPF102 Gate (but he didn't really have to do this). 

DOES ANYONE KNOW WHO BUILT THIS RECEIVER?  

ARE THERE ANY OTHER HERRING AID 5s OUT THERE?

DSG

DGS! 

Click on the images for better views.

FLASHBACK: The Herring Aid 5 Direct Conversion Receiver and Frank Jones (Video)

The Radio Gods seem to be pushing me towards Direct Conversion receivers.  This week I was speaking via Zoom with the very FB L'Anse Creuse Amateur Radio Club in Michigan.  My Herring Aid 5 tale of woe came up (see video above).   Then Dean KK4DAS was sharing video of the amazing fidelity of the Pete Juliano Direct Conversion Receiver.  Then I started thinking about Frank Jones W6AJF, and the story (fictional) of his build of the Herring Aid 5 by Michael Hopkins AB5L: 

----------------------

I gave Frank a board for the Herring Aid Five redux from the April 1998 QRP Quarterly and challenged him to build one up. It took maybe two hours and that includes his own touches which included refusing to buy any parts.

For the transformers, he calculated the turns ratios from the impedances and tested a bunch of TV set pulls 'till he found something close. But he made the output 1:1 because his Brandes phones are close to 1000K Ohms as it is. 

He was willing to use toroids, but not to buy one, so I gave him an Amidon circular and he calculated the values of the 18 specified units. Then he wound them on unidentified cores from my junk box after learning the permeability of each with his homebrew dip meter. 

A store bought Zener was out of the question so he mixed and matched regular diodes with transistors hooked up as diodes until he got close enough to 10 volts. The mosfets came out of a TV tuner and Frank will use any plastic bipolar that says "C" or "D" on it for a 2N2222. 

Of course it worked the first time. He rigged up a patch to a pair of Class A push-pull 6L6s so Christie could hear it and she said it was "Also cute but bigger than the other one." 

Now a real QRPer would cry at that, but not Frank who sees no advantage in miniaturization at all. In fact, he mounted the whole thing in an old case from a Collins 6 and 2M transceiving attachment he junked out for the parts and no two knobs matched as Frank thinks matching knobs slow you down in a pileup. He wanted to take it back to his own shack and try it out with his breadboard MOPA and pair of 100THs because he does not run QRP, saying it "transfers the burden to the other guy."  

-----------------

Frank Jones was one HARD CORE HOMEBREWER.  No store-bought Zener diodes or toroidal cores for him! 

All of the SolderSmoke Herring Aid 5 articles can be found here: 

https://soldersmoke.blogspot.com/search?q=Herring

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

I Too Built a Tuna Tin 2

I didn't plan on doing this.  I didn't even really want to do this.   I've become a phone guy -- I'm not into CW anymore.  I figured I'd just finish the Herring Aid 5 receiver and settle the score from 1976 and that would be it.  But everything I read about the Herring Aid 5 included references to the iconic Tuna Tin 2.  Obviously I was also under the strong influence of my late February encounter with the original TT2 at the Vienna Wireless Winterfest.  That Mojo is powerful stuff!   Then my wife brought home this can of Russian tuna.  The dimensions were perfect.  Then I looked in my junkbox and found 40 meter CW crystals.  That was it. I had to do it. 

I built mine Manhattan style, using several of W1REX's fantastic Me-pads.   I also used as the final a transistor that Rex gave me at Winterfest. Thanks Rex.  Soul in the New Machine. 

I'm getting about 200 mW out.  I;m on 7030 kHz and 7040 kHz and 7110 kHz.   I have the TT2 up with my Drake 2-B (Herring Aid 5 integration will come later).  I can feel the Mojo. 

I just had my first contact with the TT2:  I called CQ on 7110 and AB2RA came back.  Jan was running 20 watts from an old 807 rig, listening with an old Hammarlund.  So it was HB transmitter and vintage receivers on both ends!  FB!





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

SolderSmoke Podcast #159: Hamfests, Herring Aids, and Tuna Tins

 

SolderSmoke Podcast #159 is available.

 



http://soldersmoke.com/soldersmoke159.mp3

April 1, 2014
Vienna Wireless Hamfest
BITX Talk
W1REX speaks
Tuna Tin 2 Mojo Transfer Ceremony
After 38 years -- finishing my Herring Aid 5 receiver
Feedback, Phasing Dots, Rotational Sense, and Oscillation (or not)
Motorboating (when you don't want to)
Building my Tuna Tin 2 with parts from W1REX
On the air with Tuna Tin and Herring Aid
More Minimalist Meanderings:
An (Almost) All Altoid Crystal Radio!
Tek 465 dies (again) :-(
MAILBAG

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

38 Year HB Mystery Solved? Was it the phasing dots?

 During the summer of 1976, at the age of 18, I made an audacious attempt to join the ranks of the true homebrewers.  I tried to build a receiver.  It was the Herring Aid 5 from the July 1976 issue of QST, a 40 meter Direct Conversion receiver intended for use with the famed Tuna Tin 2. As I have recounted (perhaps ad nauseum), I never got it to work.   My recent encounter with the ORIGINAL Tuna Tin 2 (Mojo was transferred to my BITX17, and it definitely works better now) got me thinking about this painful experience.   I decided to try again.

There is an updated NORCAL schematic for this rig.  I found it (and some good articles) on the NJQRP club page.   In the original, designer Jay Rusgrove, WA1LNQ, used only parts that could be found at Radio Shack stores.  In the days before the internet and Mouser, this was a good idea.  Instead of toroidal ferrite and iron powder coils,  Jay built his coils around Radio Shack solonoidal 10 uH chokes. 

The NORCAL version dispensed with the Radio Shack chokes, and used toroids.  But I wanted to try to find out what went wrong 38 years ago.  So I dug up some 10uH chokes. 

I know that my problem was that I never got the oscillator working.  I remember being able to hear signals with my "almost" receiver when I put my HT-37 in "CAL" mode and tuned through 40.  I was so close!  The Herring Aid was picking up RF from the HT-37 and using that in lieu of the LO energy that obviously wasn't coming from my Herring Aid VFO.  But WHY didn't that oscillator work?

Today I started with the VFO.   Again, it didn't work!   But now I have decades of troubleshooting experience under my belt.  So I poked around a bit.  Then I decided to look closely at the phasing.

Take a look at the schematic(above) and the picture (below).  L7 is the 10uH choke.  L6 is 4 turns wound over it (or adjacent to it).  Now, here is the key question:  Look at the phasing dots.  How would you guys connect those coils?   For me, the schematic indicates that the TOP of L6 should go to the Zener and the BOTTOM of L6 should go to the drain of the JFET.   The TOP of the choke should go over to C5, and BOTTOM of L6 should go to ground.  Right?  Or am I reading the phasing dots wrong?

Well, the oscillator was not oscillating in this configuration.  Then I did something that I might not have known to try back in 1976:  I reversed the phase of L6:  I put the top of the coil to the Drain of the JFET and the bottom of the coil to the Zener.  Bingo.  The joy of oscillation.  Now it works.  (The picture below shows it as it is when the oscillator is working well.)

So,  is there an error in that diagram?  Was this not all my fault?   

Aha! I just looked at the schematic of the NORCAL version.  Check out the dots!   I think that was the problem!

 

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Herring Aid: It was NOT the dots! Rotational Sense and Phasing

Opposite "sense" winding and resulting phase shift

My second attempt at building a Herring Aid 5 (the first was 1976) continues. 

I thought I had discovered an error in the schematic that (I hoped) explained my failure to get this simple receiver running (scroll down for details).  But Dex, ZL2DEX,  in New Zealand spotted something that got QST off the hook and put all the blame back on me:

I had failed to check the rotational sense of the windings.  The schematic called for 4 turns over the Radio Shack choke.  So I just went ahead and wound them.  I didn't pay any attention to the direction of the winding.  I then hooked it up in accordance with the phasing dots in the diagram.  And it didn't work.  So I switched the coil connections around.  And it worked.  Aha! I thought! QST messed up!  It wasn't my fault. 

Dex brought me back to reality.  He noted that I probably wound the coils with the wrong rotational sense.   I confirmed this.  I rewound the coil following the rotational sense of the choke.  I hooked it up following the phasing dots of the schematic.  This time the oscillator started right up.  So the problem wasn't an incorrect drawing of the phasing dots.  Instead it was my failure to remember that phasing is more than just the top or the bottom of a transformer's winding.  Rotational sense is also important.  That's why "phasing dots" are sometimes referred to as "sense dots."

This doesn't come up very often, because most of the toroidal transformers we make are bifilar or trifilar -- the windings are always in the correct sense because we twist the wires together before putting them on the coil.  When we look at those phasing dots, we are focused on getting the proper tops of coils connected to the appropriate bottoms of other windings.  We don't pay any attention to the sense of the windings.  Thanks to Dex for bringing me back to my senses :-o

Grob's Basic Electronics has this definition for those phasing dots:

"	Used on transformer windings to identify those leads having the same instantaneous polarity."

This morning I did a little experiment to confirm all this:  I took a toroidal core and wound a little transformer.  Using a dual trace scope, I looked at the input and output wave forms.  Sure enough, when the windings are in the same rotational sense, there is no phase shift.   But when that secondary is wound in the opposite sense, you get a 180 degree phase shift.  I know this is very basic, but it was fun to re-learn it and to confirm is.

But I still don't have the little receiver running.  I think there are a few problems.  That single BJT mixer stage needs a lot of RF (2.5 volts p-p) from the oscillator.   Also, I think the 10 uH chokes that I am using are not the same as the chokes used in the original Herring Aid design.  So when I build transformers on these chokes, they don't work very well.

But I will keep at it.  It has been 38 years... I can wait another week or two.   

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

A Big Error Discovered in the 1976 QST "Herring Aid 5" Article (After 47 Years)

Click on image for a better view.  See arrows for Q1, Q5 and the parts list.

I tried as a teenager to build the Herring Aid 5 direct conversion receiver from the July 1976 issue of QST.  I could not get it to work. Important points: 1) I was attracted to the fact that this receiver used only parts available from local Radio Shack stores (I bought them) and 2) The article provided a PC board pattern (I also bought ferric chloride and etched a board). 

Looking back, I concluded that I had failed to get the VFO to oscillate.  I remember hearing signals when I tuned my HT-37 transmitter (on Cal, on 40) near the receiver.  I was very close, but I never got that Herring Aid 5 VFO to oscillate.

Thirty-eight years later I tried again to build the receiver.  Important points:  This time I used mostly junk box parts and Manhattan-style construction (no etching).  Still I could not get the VFO to work.  ZL2DEX spotted a problem -- I had wound the L6 and L7 coils with the wrong "winding sense."  I corrected this, and BOOM! the VFO sprang to life.  I assumed that I had made a similar "winding sense error" way back in 1976.  This, I thought, explained my failure to get the receiver working.  The QST article had warned that proper phasing of L6 and L7 was necessary.  I figured that I just hadn't fully understood what "proper phasing" meant.  So it was, I thought, all my fault.    

 

Here is the PC board pattern from QST.  Arrows show Q1 (DGS) and Q5 (DSG).  

But it is the same kind of FET!  Click on the image for a better view.

But then on October 17, 2023 a comment appeared on the SolderSmoke YouTube channel.  Rick WD5L had also -- back in the late 70's -- tried to build this receiver.  He recently looked closely at the recommended parts list (that we used!) and at the QST PC board pattern (that we also used). AND HE SPOTTED AN IMPORTANT ERROR IN THE QST PC BOARD PATTERN.   

Take a look at the pattern for Q5 above (see arrow).  That is the VFO FET.  A Radio Shack 2035 FET has a DGS pinout (see below).   The Gate is the center pin.  If you put this transistor into the PC board pattern above you would definitely be grounding the Gate.  There is no way the VFO would work under these circumstances.  Note too that the only other RS 2035 FET in the receiver is Q1 (the RF amplifier).  In the PC board pattern above Q1 is marked correctly as DGS.  This confirms the error in the Q5 PC board pattern.  There is no way an RS 2035 transistor can simultaneously have two different pinouts! 

Wow.  So this failure to get the VFO working may not have been my fault after all.  I may have actually gotten the transformer winding correct, but even if I did, there is no way this VFO would have worked using the part called for by QST and the PC board pattern shown above.  As a teenager I just did not know enough to spot the error or the inconsistency.  I kind put blind trust in QST.  I just couldn't get the thing to work.  

Rick searched the QST archives to see if they ever put out an errata on this.  So far, nothing. Worse yet, the scan of the PC board pattern on the QST site is very unclear and may have the pin designations on Q5 scratched out. This would make it more difficult to spot the problem.  (The image above is not from ARRL.  It is from a high quality scan of the original QST article done this week by a fellow Vienna Wireless Society member.)  Please let us know if you find any kind of errata or any acknowledgment of error.  

This is really pretty bad.  This was a project aimed at novices.  Far from encouraging homebrewing, this type of mistake is the kind of thing that would push people away from the soldering iron.  

Ironically, I may have been doomed by opting to use the QST PC board.  If I had used Manhattan-style construction (as I did in my more recent build) I would not have fallen victim to this PC board pattern error.  Also, if I had built this thing stage-by-stage (as we always now recommend) I would have more clearly realized (back in 1976) that the problem was in the VFO stage.  But I was 17 and didn't know.  I put blind faith in the QST article.  It never occurred to me that something in print could be wrong.  This realization came much later. 

There is more to talk about on this ill-fated project. In future posts I will discuss another error, this one in the AF amplifier.  And possible additional errors...  And I'll write about the 1998 resurrection of this project by NORCAL QRP and the New Jersey QRP clubs.  

Thanks to Rick WD5L for spotting the PC board error. 

First Contact with Herring Aid 5 AND Tuna Tin 2

Ah, it was a good morning in the N2CQR shack!  Last week I ran into fellow ham David Cowhig at work.   I was regaling him with tales of Herring Aid and Tuna Tin derring-do.  Oh the stations I had heard with the receiver!  And the stations that I'd worked with the transmitter!   Then David asked the question: "Yea, but have you worked anybody with the receiver paired up with the transmitter?"  Uh, no.  Not yet. 

 

Well this morning I took care of that.  7040 kc.   1115 UTC.  W4ELP was calling CQ.  He wasn't too strong, and I wasn't sure if we were on the same side of zero beat (that's what happens with direct conversion -- you get all the sigs in two places on the dial) but I took a shot at it.  And he heard me! 

 

Here's the icing on the cake:  This was his SECOND QSO with my Tuna Tin 2!  Ed had been contact #4 when I was running the TT2 with the Drake 2B.   After exchanging reports he asked "Bill ARE YOU STILL ON THE TUNA TIN?" 

 

The rig (TX AND RX) is pictured above.   Close-up of the receiver appears below.  And below that is a picture of Ed, W4ELP, in his Georgia shack.  Note the HW-8.

 

Thanks Ed! Thanks David!

 



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

Can You See an Error in the Herring Aid Five Schematics?

Something caught my eye this morning.  Please take a look at the audio amplifier stages (Q3 and Q4) on the Herring Aid Five.  Can you see an error? Above is the original schematic from the 1976 QST.  Below is a 1998 update by VK1GB and KI6DS.  I see the same problem in both schematics.  Please let me know if you see an error. 

SolderSmoke Podcast #245: Cuban DSB, DC Receiver?, Can you spot the AI? (Prize), Winterfest Loot, Gina's Podcast, 6BA6 buy, MAILBAG

 

DC RX Example by KK4DAS

SolderSmoke Podcast #245 is available for download: 

Audio Podcast:  http://soldersmoke.com/soldersmoke245.mp3  

Video:  (68) SolderSmoke #245: Cuban DSB, DC Receiver?, AI, Winterfest Loot, Gina's Podcast, 6BA6 buy, MAILBAG - YouTube

Travelogue: Cuba DSB and AM. Jose CO6EC and the Islander. We need more info, especially on the solid state Jaguey rig.

Bill’s bench:

Will the High School DC receivers get finished? Future uncertain. But the project was technically interesting. Great working with Dean KK4DAS. Battling AM breakthrough from Radio Marti. We joked that Dean has been listening to Radio Marti so much that even though he doesn’t speak Spanish, he has noticed an increased urge to liberate Havana.

Audio amps: Harder than we thought. Lots of variation in Hfe of 2n3904s. Oscillations.
Not using feedback amps nor LM386s, nor push-pull. Simplicity is a design goal.

Fixing the tuning (bandspread) problem on the VFO was fun.

Antennas? A quarter wave with ground or counterpoise works well. We tried it. (59) An Antenna for the TJ 40 Direct Conversion Receiver - YouTube
----
Back to work on the uBITX. I chickened out on replacing the predriver with a BFR-106, but then – Just in time Todd K7TFC and his Mostly DIYRF came out with BFR106 boards! TRGHS. I will do the mods on two uBITX transceivers. I even bought a solder-sucking iron for the second job.

Winterfest Hamfest. Big success. Thanks VWS. HERRING AID FIVE! Simpson 260! QF-1, Another Radio Shack DMM, Eamon Skelton’s Homebrew Cookbook, Knobs, SWR meter.
----

SHAMELESS COMMERCE: 

-- Todd’s Mostly DIY RF and the BFR106 boards, and much more: https://mostlydiyrf.com/

-- Become a Patreon sponsor of SolderSmoke: https://www.patreon.com/join/4785634/checkout?ru=undefined

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Pete's Bench: 

Technical Note: Skype problems. Pete's Skype kept dropping out. Bad in the last podcast (#244). Three minute gap. I was ready to scrap the whole podcast when Dean KK4DAS offered to help. And he is obviously well qualified: https://potomacofficersclub.com/speakers/dean-souleles/ Dean went to work with AI. And he was able to fill the audio and the video gaps. Can you spot the three minutes of AI? Send me an e-mail with the time segment of the AI/Deep Fake portion of SolderSmoke 244. The first one with the correct answer will win a prize. 

SolderSmoke #244:

https://soldersmoke.blogspot.com/2023/03/soldersmoke-podcast-244-pete-is-back-tr.html 

Thanks Dean!

----Interview on his Pete's daughter’s podcast. https://soldersmoke.blogspot.com/2023/03/listen-to-pete-juliano-on-his-daughter.html

-- 6BA6 e-bay buy. Will we see an all 6BA6 rig from Pete?

-- The NCX-5 on e-bay

PETE’S NEW BLOG: https://hamradiogenius.blogspot.com/

Mailbag:

-- A New SPRAT arrived in the mail. PH2LB’s Gluestick on the cover.
-- Will KI4POV – Awesome homebrew – on the blog.
-- Sands, VK9WX listening to SolderSmoke on Willis Island! Wow. 
-- Andreas DL1AJG in Germany continues with the Electronics for Biologists DC RX build.
-- Dean KK4DAS and his homebrew 10 meter DSB rig.
-- Jim W2UO built a Michigan Mighty Mite and made a contact.
-- Dave K8WPE and the E in IBEW. We need new stickers.
-- Bob KC4LB – Surface Mount is SMALL.
-- Bruce KK0S on the Herring Aid 5 Board.
-- Chuck WB9KZY on Nuclear Monopole Resonance very cool video – on the blog.
-- Alan WA9IRS wants a CW editor for his phone. Really.
-- Vic WA4THR also working on uBITX power out improvement.
-- Tobias weighs in on Kludge. As in Fudge.
-- Tony G4WIF notes that when he changes his oil he often removes sludge, not slooge.
-- Consultations with Lexicographer Steve KB3SII.
-- Walt AJ6T says CW operating declined after FCC ruling in 1970s about callsigns.
-- Ramakrishnan VU3RDD now VU2JXN has joined the VWS. An old friend of SolderSmoke. Urged us to launch a blog back in 2008. We announced his daughter’s birth - - now Ram is getting ready to build a DC receiver with her.

Some notes on the Herring Aid 5

Sure, this receiver is not "state of the art."  But that's the whole point.  I wanted to finish the receiver project that I couldn't finish back in 1976. 

I tried to stick as close as  possible to the original design and parts.  NORCAL came up with an updated schematic in 1998 with parts that are more readily available.  But Designer Jay Rusgrove was shooting for something that could be built with all the parts coming from Radio Shack.   I think that is probably one of the factors that attracted me to the project way back when.  That's why Jay went with varactor tuning (no hard-to-get variable caps!).  And that's why he used coils that were wound  on Radio Shack 10uH RF chokes (no need for hard-to-find toroidal cores).  In this sense there is some common ground between the BITX rigs and the Herring Aid 5.

I stuck with the RF-choke as a coil idea for the VFO, but went with the NORCAL-prescribed toroids for the front end and mixer coils.  (I may go back and try to use chokes in these circuits, but I'm not sure my junk-box will yield the kind of RF chokes that Jay used).

I wish I had known a few things when I was building this back in 1976: More knowledge about how to wind the coils would have been a big help.  I wish I had realized that I could use a SW receiver to get the oscillator on the right frequency. I guess this was in the days before Ugly and Manhattan building techniques, but it would have been nice to know that there was no need to actually etch a board for this project (I did!).

The coils really are a bit tricky.  Jay didn't use any trimmer caps, so I guess you had to just hope that the front end coil and cap resonated somewhere near 40 meters.   As for tuning the oscillator, Jay recommended scrunching and un-scrunching the turns on the RF choke.  Yikes!  Give me some trimmer caps! 

I also found that you have to watch the level of the RF going from the oscillator to the mixer.   Too much, and the receiver is deaf.  Too little, same result.    You need to experiment a bit with the number of turns on the pick-up coil from the oscillator.   

The warnings about the pitfalls of that single BJT mixer were right on the mark:  Lots of AM SW breakthrough.  But I kind of like the background music.   Strong RFI from local FM broadcast stations was another story (WMZQ is a country music station!).  I reached into my junkbox and found a low-pass filter from a Heathkit DX-60.    I just put that between the antenna and the receiver and the country music was GONE! 

I really love this little receiver.  I have it playing 40 meter CW as I type.  It sounds great.   I feel the urge to built a Tuna Tin 2 and put both of them on 40. 

In the original Tuna Tin 2 article, Doug DeMaw notes that Jay Rusgrove was thinking of doing a companion receiver and says that he was thinking of calling it the "Clam Can 5" !  There were jokes about receivers for hams with "tin ears" and about there being "something fishy" about these rigs.

Thanks to Doug DeMaw and Jay Rusgrove and QST for bringing us these little circuits. 


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

Making Fish Soup from Herring and Tuna (How to Build a Fish Soup 10 Transceiver)

Just in case some other fanatic someday thinks about trying to turn a Herring Aid 5 and a Tuna Tin 2 into a Fish Soup 10. This will also serve as a note to myself on how I did this.  Above are my suggestions on how to get the VFO signal into the transmitter and the receiver.  Both RX and TX can easily be returned to their original condition. 

A Fishy Rig: Herring Aid Five, Tuna Tin Two, VU2XVR Key

Haunted by a fear of rapid expulsion from the QRP Hall of Fame, I decided that I should immediately do something to establish some form of QRP street cred.  Looking around the shack, I realized that all of the ingredients were there:  My Herring Aid Five Direct Conversion receiver (completed after only 38 years), my Tuna Tin Two transmitter, the VU2XVR key that Farhan gave me, one 7050 kc  FT243 crystal.   I put it all on a piece of scrap plywood. A couple of nice connectors from W8NSA supported the DPDT T/R switch and the coax connector. I keep the receiver LO running all the time.

Now, let's be clear: running 250 milliwatts, rock bound with a Direct Conversion receiver that tunes both sides of zero beat is not for the faint of heart.  The log book does not fill up rapidly. But hey, I made one contact the following morning.  K1PUG said I was 559 in Connecticut.      

Long Lost Varactor Receiver Found!

SolderSmoke fans will recall that for a long time I have been looking for the radio magazine article that propelled me into a  receiver construction project that failed and left me tech-traumatized. I tried to build a solid state receiver back in high school.  All I remembered about it was that it was direct conversion and varactor-tuned.  And that I couldn't get it to work. I think the problem was in the oscillator.   

Well, I think I found it.  Chuck Adams and the qrp-tech guys were talking about a receiver project and someone mentioned the old Herring Aid Five, a receiver companion to the famed Tuna Tin Two.  That got me thinking.  The time of publication was exactly right: July 1976.  I had just graduated from high school.  This morning I renewed my ARRL membership and then immediately accessed the QST archives.  Sure enough, the Herring Aid Five is varactor-tuned.  That has to be it. 

So this one is now definitely on my to-build list.  I will finally get this receiver working.  Sometimes projects take a long time...  Thanks again to all those who helped me in this search. 

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

Herring Aid Error: C14

Yea, take a look at C14 in the AF amp.   At 1000 Hz 10uF is about 16 ohms.  That would put a serious dent in the AF gain.  And indeed, when I went back to my Herring Aid 5 (38 years from start to finish) and pulled C14 out, there was a dramatic increase in AF gain.  

Mistakes happen, but I wonder if anyone else spotted and reported this one.   Could someone with access to the QST archives check to see if an Erratum was ever published?   The project also appears in the 1977 ARRL book "Understanding Amateur Radio" with the problematic C14.  My guess is that it was just an error in the value of the cap.  

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.  

Kirk's Herring Aid, Tuna Tin, and Regen Adventures

 

Hello Bill!

 

Just a quick hello from MN to tell you how much I have been enjoying your podcast. Although I have "plugged" your stuff in multiple magazine columns over the years, I'm a bit late getting into the listening game. My current contract job has me doing a lot of driving, however, so I now have several years' worth of soldersmoke to enjoy.

 

Several of the most recent episodes have made it clear that we have covered some common ground in our amateur radio careers.

I was licensed in 1977 at age 15 -- a year after I built my Tuna Tin 2 :) The transmitter was a smashing success. I used it with my Tempo One transceiver, or at the electronics repair shop at a local National Guard base (where my mom worked as a civilian administrator). I would ride my bike to Camp Ripley (only 8 miles or so), and the guys in the signal shop would let me use the shop's Collins KWM-2 HF transceiver (and attached dipole). Other than my efforts, I don't think the KWM-2 got much use...

 

I, too, tried to get the Herring Aid 5 to work, with no luck at all. Listening to your podcast was like being in a time machine of sorts :) I wonder if I got the "sense" of the oscillator secondary messed up? I never did get that thing to make even a sound. I don't have it any longer. The same goes for the TT2. They got "lost" when I stored a bunch of stuff at my dad's place in-between moves, as did a home-brew 4-400A amplifier and a 6146B amplifier for my Ten-Tec Argonaut. Darn!

 

Don't forget about the matching VFO -- the Chopped Beef Slider (CB Slider), which was built into a chopped beef can, of course! I didn't build one, but as I recall it was a diode-tuned 40-meter VFO for the TT2.

 

Your "regen rage" and its subsequent easing was also amusing. I have had a love-hate relationship with those buggers, too, although mine was mostly love. You referenced Dave Newkirk's (now W9VES) 40-meter QST regen article in a podcast. I was fortunate enough to be a QST editor at the time Dave was in his "second residence." That guy forgot more about receivers than I will ever know, and he helped me tremendously in official and unofficial capacities.

I have attached a photo (above) of a multiband regen that Dave helped me build (he designed and dispensed wisdom while I built the radio). He took a schematic from a 1930s ARRL Handbook and tweaked it a bit, helping me add a VR tube, "more modern" tubes and a few other goodies. Just to be difficult, I sampled the tank circuit with a tiny-value capacitor and a high-gain MMIC amplifier so I could drive a frequency counter, which displayed the receive frequency as long as the tank was oscillating. It was fun, but it was difficult to isolate the digital noise from the counter, so I only really turned on the counter as necessary, or to calibrate a dial, etc. The chassis used to be an Eico audio signal generator... In the photo the Jackson Brothers dial and bezel/tuning scale isn't completely installed. After sitting in a box for 25 years, the regen still works but probably needs new tubes, as it's rather deaf :) Blasphemy aside, I'm moving on to solid-state regens...

 

I, too, just got a Rigol DSO. Wow, the "one-button" measurement is almost too easy.
 

I'm prepping my book, Stealth Amateur Radio, for release on the Kindle (and maybe other e-book formats), but it's available now from my website, www.stealthamateur.com.
 

Keep up the good work, Bill.

I'll be listening. :)

73,

--Kirk Kleinschmidt, NT0Z
  Rochester, MN

Editor, 1990 ARRL Handbook
Technical Editor, Ham Radio for Dummies
QST Assistant Managing Editor, 1988-1994
Ham Radio Columnist since 1989 for:
   Popular Communications
   Monitoring Times and now,
   The Spectrum Monitor (www.thespectrummonitor.com)

My book, "Stealth Amateur Radio," is now available from
www.stealthamateur.com and on the Amazon Kindle (soon)

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

The Road to QRO Perdition

I want to start out by saying that this is NOT my fault.  I have been TRYING to do QRP things. Remember my recent Tuna Tin 2, Herring Aid 5 rig?    I am aware of the ever-present threat of expulsion from the QRP HoF.   We all remember what happened to poor Pete back on April 1, 2017. 

But sometimes people just deliberately put temptation in your path.   That is what happened this week.  Our old friend Rogier KJ6ETL (formerly known as PA1ZZ) sent me the very LARGE chunk of aluminum that you see in the picture above.  Look at that thing.  It is practically begging to be turned into a very QRO push-pull amplifier.  

At first I told myself that it would be impossible to tap the big heat sinks on the sides.  How would I get the drill in there?  But then I realized that I can just put the threads in from the outside.  I can almost smell the machine oil. And the heat sink compound... 

Thanks lot Rogier. This is all your fault.