Troubleshooting an Intermittent with Mr. Carlson. And Troublesome Tube Re-Branding.

This is a really great video on how Mr. Carlson (VE7ZWZ) did troubleshooting on a tube-type receiver. The problem was an intermittent.  They can drive you nuts, but Mr. Carlson show us how to stay sane. 

-- His use of ordinary observation at the start of the process is very important.  He notices a flickering glow in the voltage regulator tube.  The flickering coincides with the intermittent noise that he is trying to fix.  That is an important clue. 

-- He also can see that the grid of one of the AF amplifier tubes is getting way too hot: grid emission.  That is another important clue.  

-- He checks the grid voltage on the AF amplifier and finds that it is way too low.  It is fine on the other side of the resistor that carries the voltage to the tube.  But it is close to zero at the grid.   This means that the mica capacitors on the grid are suspect. 

-- He uses some fairly esoteric test gear -- a homemade device and an an old Heathkit signal tester -- to check his diagnosis.  They confirm that the mica caps are the problem.  He replaces the caps and the problem is gone.  A very satisfying troubleshoot. 

Mr. Carlson presents us with a lot of good info: 

-- 6K6 tubes were often in fact 6V6 tubes.  And 12AX7s were often 6VJ8s!  Manufacturers were deliberately re-branding tubes. So we shouldn't be surprised if some of our solid state devices turn out to be a bit different from what was promised.  This practice goes way back. 

-- I liked Mr. Carlson's final sensitivity test on the receiver -- he just waved his hand near the antenna connection and we could hear the receiver respond.  Excellent. 

-- Mr. Carlson is very negative about the use of polystyrene caps in oscillator circuits.  But we these simple and cheap caps being used to good effect in oscillators in India.  

-- The leaky and bad micas were a bit surprising.  Carlson speculates that their proximity to heat-producing resistors might have caused the trouble. 

Finally, it is interesting to hear the Canadian pronunciation of radio words:  Solder with the L pronounced (as in the UK).  Farad with the second A long and the final D emphasized (I say it just as the first two syllables of Michael Faraday's last name). 

Thanks Mr. Carlson. 

Mr. Carlson Restores an All-American Five -- Tribal Knowledge! SITS! Flattening the Curve! (video)

It is always a pleasure to see a new video on Mr. Carlson's awesome YouTube channel, especially in these days of Staying-In-The-Shack (SITS).  Obviously Mr. Carlson is doing his bit in this area.  FLATTEN THE CURVE!   Thanks OM! 

My recent bout of S-38E madness has peaked my interest in the All American Five design, so this March 10, 2020 video was especially interesting to me.  Mr. Carlson puts out so much great tribal knowledge.  I didn't know about "rounder" resistors.  I didn't know that you have to be careful not to short out (to the IF can case!) the 455 kc transformers.  I really like his approach to dial cord restoration.  

Mr. Carlson's discussion of the adjustment of the front end tuner circuit on this broadcast band radio was very interesting.  Unlike the S-38 radios, there are no front end coils being switched in as you change bands. In fact, it appears that that big coil/antenna inside the back cardboard piece IS the front end coil.  This discussion has caused me to question my front end alignment technique for the S-38E.  Did I have an appropriate antenna or antenna substitute across the antenna terminal when I set the peak on the input LC circuit?   I will check on this.  Hooray!  One more thing to do during the COVID-19 SITS period.  

UPDATE:  I checked on this using the test set up described in an earlier post, but this time with my antennas connected.  First with a 40 meter dipole, then with my 130 foot doublet, then with a 50 ohm dummy load I was still able to see the resonance dips at exactly where I wanted them to be. 

My favorite bit of Carlsonian wisdom from this video?  Mr. C's confirmation that some hum in All American Five receivers IS NORMAL!  (This may be too much for the folks who find normal band noise to be offensive.)  

Mr. Carlson's Grand Receiver Restoration Project -- Your Input Sought (video)

Mr. Carlson (VE7ZWZ) is launching a series of videos on the restoration of some old boatanchor receivers.  I have been working on an old HQ-100, so this all resonates well with me. 

He asked for viewer input on which of these receivers he should work on first.  I voted for the SP-600 because I wanted to see how difficult it really is to change out the infamous Black Beauty capacitors.  My second choice was the R-390, but I warned Mr. Carlson that he might need a chassis crane for that one.  No kidding.  Really.   

I look forward to watching the series.  Thanks in advance Mr. Carlson. 

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. 

Mr. Carlson Replaces Old Capacitors -- Bathtub Capacitors

I recently posted a video from CuriousMarc about whether or not to replace electrolytic capacitors in old pieces of gear.  This is a hot topic in restoration circles. 

This week Mr. Carlson put out a video (above) in which he got rid of a bunch of "bathtub" capacitors in an old receiver. 

One of the many interesting things in Mr. Carlson's video was how his test gear initially showed the old capacitors to be good, but on further examination with better test gear he found them to be BAD! 

Out with old, in with the new!  

Wow. Mr. Carlson's New Old-Time Radio and Test Gear Lab. VE7ZWZ -- Homebrew Hero

It has been a while since we last visited Mr. Carlson's lab.  As always, we found it amazing.  The awesomeness just keeps increasing. Previous visits: https://soldersmoke.blogspot.com/search?q=Carlson

As was the case before, this is really almost too much.  THREE DX-100s in the shelves.  A massive collection of tubes, some sorted, some un-sorted.  But don't worry -- Paul has a good memory and remembers where everything is.  I believe him. 

For his amazing shack and workshop(s) and for his willingness to repair old-time test gear, Paul VE7ZWZ clearly deserves homebrew hero status.  

Thanks Paul. 

Mr. Carlson's ART-13 Transmitter (with Dynamotor)

Here we have a really cool video from Mr. Carlson.  In it he reveals (admits!) to what we already know:  HE IS A HAM RADIO OPERATOR.  FB Mr. C!

You can see that he is a true ham, with a true case of THE KNACK, when you see his reaction to the inside view of the ART-13.  He seems to gasp as he notes that there is a lot of "RF goodness" in that box.   There is a vacuum relay, a bread-slicer capacitor, there is even a variometer. And lots of good, big THERMATRONS.  Only a true ham, a true Knack victim can recognize this RF goodness. 

The Dynamotor that goes with this transmitter is really interesting to me.  I have been hearing these things whining in the background (audible noise, not a signal defect) on many early morning (Saturday 3885 kHz) of the Old Military Radio Net.  I can often hear the dynamotor of Buzz W3EMD as he transmits from Rhinebeck, New York.   It was great to see the inside of this device.  

Back in 2017, Hack-A-Day took a look at Dynamotors: 

https://hackaday.com/2017/07/04/retrotechtacular-dc-to-dc-conversion-rotary-style/

There are several good ART-13/BC-348 pictures on W3EMD's QRZ page:

 https://www.qrz.com/db/W3EMD   

I was especially taken by the handwritten frequency chart on the front panel of the ART-13.  This reminded me a lot of the handwritten readout that I have been using on various rigs, including (most recently) the 15-10 SSB transceiver. I hope Paul focuses on this paper-and-pencil frequency chart;  it is nice to step away a bit from the glowing numerals of San Jian. 

Mr. C points out that the ART-13 was the transmitter that was paired up with the BC-348 receiver.  He will be working on both in the weeks ahead. 

Thanks Mr. Carlson. 73 OM. 

Mr. Carlson's Lab Attacked by Dangerous Canadian Snow Static! (Video)

Even when describing something as simple and basic as snow, Mr. Carlson is electronically awesome.   This video made me realize that in the event of an EMP, his will probably be the only lab to survive.

The SolderSmoke Daily News took up the topic of snow static back in 2011.  Be sure to read the comments, especially the one from KC7IT about the QUARTER INCH ARCS that woke him up in the dorm at MIT.  Check it out: 

https://soldersmoke.blogspot.com/2011/10/snow-static.html#comment-form

I've got to get one of Mr. Carlson's 2020 calendars! 

  

Mr. Carlson Restores a BC-348 -- But 40 Meters Sounds Very Weak. Why?

Mr. Carlson mentions that he is a ham radio AMer.  He is also on SSB, but AM is, he says, his preferred mode.  FB. 

I got a real chuckle about the MVC switch position on the front panel.  "Manual Volume Control"  like "Manual Gain Control."  I thought I had invented this term.  You know, "real hams control their gain manually."  This is why Farhan never put AGC in the BITX20. But it seems the Army Air Corps was way ahead of me with the BC-348.    

Mr. Carlson makes it sound (!) like the Dynamotors are a thing of the past.  Not true.  Every Saturday morning I listen to the Old Miltary Radio Net and hear a number of Dynamoters spinning in the background.  One belongs to Buzz W3EMB who uses a BC-348.  Buzz has an SDR attached to the IF of his BC-348, which I think is an admirable mix of the old and the new.  Those BC-348s are, after all, quite old.  WWII old -- like 85 years old.  And still working.  

Paul has a good discussion of the importance of short lead length, and of mounting shielded capacitors properly, and of the usefullness of a good groundplane under the capacitor.  Go Manhattan boards!  Paul's presentation on how to identify the outside foil of a capacitor was very good, but I was wondering if you could also find out by using a file to remove some of the yellow insulation, then test with a DMM to see which terminal is connected to the foil. 

"Lots of times you have to add solder to remove solder."  Indeed. 

The importance of testing for BOTH capacitance and leakage.  Yes. 

But why bother with "period correct" internal wiring harnesses, when you have already put a bunch of modern caps in there?   I mean, I'm in favor of the re-capping, but this seems inconsistent with the need for "period correct" internal wiring harnesses. 

When Paul first fired up the receiver, I was hoping he would disconnect the antenna to see how much band noise was getting through. 

When Paul got to the IF alignment, he spoke of the dangers of working on energized high-voltage gear.  I had been thinking about getting a BC-348 myelf, but Paul's comments reminded me of why this is probably not a good idea for me.  Paul's comments about "knowing where your hands are" is on target.  "One hand behind the back, " is a good rule for this kind of energized testing -- this will help prevent current from a mishap from flowing through your chest.  

I may have more comments later.  Off to the beach now.  

Back from the beach:   

"Contrary to popular belief, the simpler the receiver, the better they hear."  Amen Mr. C. 

Paul's heroic cleaning of the 915 kc crystal made me feel like a wimp for not having tried to do this with some "bad" 455 kc rocks I was given while trying to build the Mate for the Mighty Midget receiver.  I may go back to those crystals and try to clean them as Mr. C did. 

The grand finale of this 2.5 hour video was, as expected, a demonstration of how good it sounds.  But unfortunately it did not sound good.  Paul tuned through the 40 meter band and I heard NO CW signals.  I didn't even hear FT8.   There were a few anemic SSB signals and, as he reached the upper portion of the band some very weak AM broadcast signals.  I didn't even hear CHU Canada's time signal.  Huh?  Why?   Our very simple homebrew Direct Conversion receiver sounds a LOT better than that.  I mean look at the sweep of 40 meters that I did using only a simple dipole:  https://soldersmoke.blogspot.com/2024/12/an-evening-bandscan-on-40-meters-using.html  Why is there such a big difference in performance? 

Could it be the antenna that Paul was using?   He was on what he calls the 369 antenna.   Could there be a problem in the receiver?  Could it be band conditions?   

Mr. Carlson's New Lab and Workbench

I am very glad to see that Mr. Carlson is NOT slowing down.  In fact he has built another lab and is ramping up.  FB!  

Mr. Carlson Makes a Thermatron Power Supply for a BC-348

When I was 14, I had to make a power supply for a Heath HW-32A.   Mine ended up working, but it was nowhere near as nice as Mr. Carlson's BC-348 supply (shown in the video above).  I didn't have a sand blaster, nor a drill press, nor much of anything else, really.  

But hey, don't real boatanchor hams use Greenlee chassis punches?  What's with the drill press and the hole saws? 

Note that Mr. C takes care to make sure that the rectifier tube is in the proper angle FOR OPTIMAL VIEWING.  That's some serious attention to detail OM.  And whoa, DELICATE SURFACE MASKING TAPE from 3M?  Respect!  Also, era-specific looming material. 

His point about the importance of the cardboard washers in the power transformer was really useful.  I hadn't thought about that. 

Here are the two previous BC-348 videos: 

https://www.youtube.com/watch?v=nX87kwSshZ8

https://www.youtube.com/watch?v=Zqe6CBe0iGs

Thanks Paul! 

Looking at the World Through a 1 inch Cathode Ray Tube (the RCA 913) (videos)

Joh DL6ID sent me the above video.  We have been e-mailing each other about the W9YEI Television Receiver built in 1939 or so.  We have kind of concluded that the builder used an RCA 913 tube as the CRT.  This was an oscilloscope tube and was often described as looking like a metal 6L6 with a tiny screen on top.   This is kind of neat -- like using something from the old days to peer into the new world of video.  

We wondered about the image persistence of this tube.  Fortunately for us, we found several YouTube videos showing recent builds or repairs of oscilloscopes with RCA 913 tubes.  

Of course, Mr. Carlson has a video on one of these devices (and -- as expected -- has another in his junk box.  Mr. Carlson has at least two of everything.) 

Here are a few other videos showing RCA 913 tubes in action. 

https://www.youtube.com/watch?v=1-qidcmN-sI

https://www.youtube.com/watch?v=IfN2mmEIfTE   (with Men at Work audio)

https://www.youtube.com/watch?v=TJF22Ra2kIM    (Summertime.... And the Livin' is Easy)

Here's a nice video from Tektronix on CRTs: 

https://www.youtube.com/watch?v=jHGAnJjnNY0

The Truly Amazing Workbench and Shack of VE7ZWZ (Video)

Brace yourselves.  This is almost too much.  Prepare for sensory overload and possible palpitations.
 
Wow.  This is really amazing.   Note the very casual way Paul manages to mix Eico 430 oscilloscopes with the latest Tek touch-screen 'scope.  Heck, the doesn't even mention the SP-600s!  He does briefly note "a very large transmitter." Indeed. And he has a microscope on the bench.

This video is part of an excellent YouTube channel called "Mr. Carlson's Lab."   Great stuff in there.  Paul works on everything from old tube type receivers to modern Yaesus and Icoms.

It took me a little digging to find his ham radio call sign.  There are many Paul Carlsons on QRZ.com, but Paul's pronunciation of "solder" gave him away.  It seems our Canadian friends also (like the Brits) pronounce the "L."  VE7ZWZ. 

Check out his channel.   Lots to learn there:   

https://www.youtube.com/watch?v=qqmegXoB7lA

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

Stepping Inside an AM Transmitter (video)

Very cool video.  We have visited VE7ZWZ's amazing shack before. This time he takes us inside a BIG commercial AM transmitter that he has modified for use on the amateur bands.

I know that he had the plate voltage turned off, but I still felt myself cringing when he reached up to touch the plate connectors on those enormous thermatrons.  The filaments were on, adding to my unease.  Dude, don't do that! And if you are standing INSIDE the transmitter, keeping one hand behind your back might not be as beneficial as it normally would be.

His comments on his VFO were interesting.  I was kind of disappointed that he went with a varactor circuit.  A varactor?   Amidst all those bread slicer variable caps?  It just doesn't seem right.  (And BTW they are bread slicers, NOT "potato slicers.")  But I kind of liked the heater--thermistor--insulation set up that keeps the VFO at constant temperature.

I thought it was interesting that these transmitters were kept on, with the tubes glowing for years at a time.

Thanks Mr. Carlson, for another great video! 

Back to Mr. Carlson's Lab

I like the Vedolyzer in the wooden box. 

Mr. Carlson's New Lab. And his Amazing Tek Collection

Some Really Amazing Test Gear

Wow. Really great test gear, and an amazing parts collection.   This guy even gets a "nice workshop" comment from Mr. Carlson.   Pac1085 seems to be in Rochester N.Y. and he says he specializes in the repair of vintage audio gear.  He should have more subscribers.  Does anyone have more info on him?  

Here is his channel:  https://www.youtube.com/@pac1085/featured

CuriousMarc Repairs the French Oscilloscope of His Youth -- ACHTUNG!

It was very cool to watch CuriousMarc go back and repair the French Oscilloscope that he used as a kid. 

I was reminded of my work on a Tek 465 scope.  There is a LOT of high voltage around those CRTs.  I needed to measure the HV on my Tek 465 -- Alan Wolke W2AEW lent me a high voltage probe. Thanks again Alan.  I eventually gave up on the Tek 465 but that was because mine had plug-in transistors.  Yuck -- one bump of the elbow during troubleshooting and you could easily inject new problems into the broken machine. 

Marc's work also caused me to think about working on the HAMEG 10 MHz scope that I have in the shack.  Also there is the older Eico scope that was so bad and so limited in bandwidth that it has been banished to the basement.  But I must say, watching Mark move around high voltage made me realize why so many of us have migrated to solid-state scopes.  I have modern Rigol scopes in both my shacks. 

As with Mr. Carlson, I must say that Marc should be more careful with energized gear and capacitors that hold their charge.   Marc seems to think that those insulating gloves protect him from HV, but he still grabs that beast with both hands and makes skin to metal contact with at least one arm.  Yikes!  Don't do that!  Volts jolt but mils kill OM!  One hand behind your back!  Marc does recognize the danger, and displays this sign at least three times during the video.  (Marc is obviously NOT a dummkopf!)     

Google Gemini said this about the sign: 

The language is German (though it is a bit grammatically jumbled and misspelled).

Translated to English, it roughly means: "Is it not for work by blockheads!" or "Is this not for use by fools!"

A Quick Breakdown

The phrase looks like a slightly mangled variation of a classic piece of old internet joke-lore known as "Blinkenlights."

Back in the early days of computing, tech rooms often had mock-warning signs posted in broken, comical German (often called "Mock-German" or "Germlish") to warn non-technical people not to mess with the machines.

If you are looking at a quirky warning sign or an old tech joke, the proper full phrase usually goes something like this:

"Achtung! Alles Lookenspeepers! Das computation-machine ist nicht für gefingerpoken und mittengrabben! Ist easy schnappen der springenwerk, blowenfusen und popencorken mit spitzensparken. Ist nicht für gewerken bei dummköpfen!"

In short: "This is serious equipment—no touching, and it's definitely not meant to be operated by fools!"

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

And be sure to check out the oscilloscope music as seen by Marc's old scope: 

https://www.youtube.com/watch?v=JCukVSqoZyI