Category: Old radio

LA6NCA’s German Military WWII Receivers, and a Luftwaffe Receiver with FAST QSY

Discussions of old military radio gear are dominated by talk of U.S. radios. Yesterday in the comments section of the SWLing Post I found two interesting videos about German WWII equipment. Above you can see LA6NCA’s receivers. Below there’s a video of a Luftwaffe receiver with an amazing capacity for really rapid frequency change.

Jean Shepherd Works Through a Satellite in a School

Ah, 1975. Obviously a very different time… I’m not sure if Shep would fit in well in the classrooms of today. There was bit of Rodney Dangerfield in his demeanor — that would likely cause some trouble.
But this clip was fun. Shep was right on target when he talked about how getting your ham license used to mean that you’d “mastered a technical art.”

The OSCAR satellite they were using was 2 meters up and 10 meters down. There was a Heathkit HF transceiver with a transverter. And a Simpson multimeter. That mic was a Turner +3

Thanks to Steven Walters for alerting us to this.

EXCELSIOR!

The VFO that I am looking for: The Globe VFO deluxe

I mentioned this in the last podcast. I’m looking for one of these. I had one as a kid, and used it with a DX-40 and a Lafayette HA-600A. It is now the only piece of gear that I need to recreate my novice station.

Does anyone have one of these, perhaps gathering dust in some corner of the hamshack? Please let me know. Thanks.
Here’s the manual:
http://www.oldtuberadio.com/data/Globe/GlobeV-10Manual.pdf

Guilt Trip: Video on the Heath QF-1 Q Multiplier

Hack-A-Day had a nice post about this piece of gear:

My radio emotions were swinging wildly as I watched this video.

Readers may recall that over the years I have brutally cannibalized several QF-1s. I was enticed into doing this precisely by the tuning cap that the videographer so alluringly describes. It has a built in 7:1 reduction drive! How could I resist? These wonderful caps live on in several of my homebrew rigs.

I also put the conveniently sized metal cabinets to good use — one holds frequency counters for my AM station, the other houses an Si5351 VFO/BFO that can be used with many rigs.

After extracting the cap and putting the boxes to good use, I was left with the remainder of the circuitry. I recently put even this stuff to use by using the coils to make a triple LC circuit filter for 455 kHz. This may someday be used in a receiver. So you see, I’ve not been wasteful.

And the thing only cost 9 bucks back in the day… So I didn’t really do anything bad. And besides, adding a regen circuit to a superhet is kind of backwards, right?

But then the video producer started talking about how nice his QF-1 looks, even after more than 60 years. And about how much it improved the performance of his AR-1. And then, the kicker: He said the QF-1s are now “relatively rare.”

I hang my head in shame. I am a serial QF-1 killer. And I don’t know if I can stop.


STOP. LISTEN. Shep on Building a Shortwave Receiver

Oh man, how could I have possibly missed this one? Perhaps I didn’t, but even if this one has been on the blog before, it is so good that it is worth repeating.

Shep really captures the frustrations and joys of a teenage radio builder. I could really identify with this. It all reminded me of my heartbreaking effort to build the Herring Aid 5 receiver.

So much cool stuff in this 1963 recording:

— The wonderful smell of radio service shops.
— The terrible shirt and tie choices of radio service guys.
— The truly dire consequences of mistakes in published schematic diagrams.
— The AGONY of not being able to get a homebrew radio to work.
— The JOY when you finally do get it to work. Shep’s “whole life changed” when that happened.
— Hugo Gernsback, Lee DeForest and “unscientific scientists.”

As the YouTube video plays, they show several covers of old Short Wave Craft magazines. At one point they show some homebrew phone rigs. I think they look like my wooden box BITX rigs. And the front panels are clearly Juliano Blue. TRGHS.

Here is the 1933 Oscillodyne article that launched Shep’s effort:

EXCELSIOR!

KLH Model Twenty-One II — Is My Speaker Dried Out?

A few years back Rogier PA1ZZ very kindly sent me a box of electronics parts. Included was an FM table-top radio with a nice walnut case. Thanks Rogier!

I hadn’t looked at the receiver in years, but this week I dusted it off and looked it up on the internet. Turns out that it is kind of famous. It was produced by the KLH company. The K stood for Henry Kloss, one of the giants of Hi-Fi audio gear. Henry appears in the picture below.

I got the receiver working, but it sounds awful. It sounds much better with an external speaker, which is disappointing because the internal speaker was the main attraction of this receiver. It even has a little badge on the front panel trumpeting(!) its “Acoustic Suspension Loudspeaker.”

I’m wondering if the problem is in fact the speaker. The cone looks intact, but it seems very dried out. It has been more than 50 years… What do you guys think? Picture above. Any other suggestions on what to do with this thing, or how to make it sound better?

Some KLH history:

https://klhaudio.com/history

https://antiqueradio.org/KLHModelTwentyOne21FMRadio.htm

KLH receiver with pillow

“Radio, Radio” By Elvis Costello and The Attractions

Wow. At one point in the video Elvis C. climbs onto a radio chassis and sings while standing between two Thermatrons. FB OM.

And here is an interesting article about Elvis Costello’s music, and opposition to Fascism.

6EQUJ5 — SNR, the Big Ear Radio Telescope, and the “Wow” Signal

https://hackaday.com/2020/11/25/the-wow-signal-and-the-search-for-extraterrestrial-intelligence/#more-448808

This Hack-A-Day article explains the significance of 6EQUJ5 on the paper readout of the Big Ear radio telescope. It is a signal-to-noise readout.

The article also has interesting information about the radio telescope that was used.

I have on my shelf John Kraus W8JK’s wonderful book “Big Ear Two — Listening for Other Worlds.” John Kraus is the guy who built the Big Ear. In a reminder of how new radio technology really is, Kraus got his start in radio as a ten year-old boy in 1920. He ripped the wire out of the ignition coil of a Model T Ford to make a tuning coil for a crystal radio. He took the earpiece out of the family telephone. His father gave him a chunk of Galena. He used the crystal radio to listen to the early broadcasts of WWJ in Detroit.



On the Cover of The Rolling Stone (Almost) — Jac Holzman, Elektra Records, and Ham Radio

Thanks to Stephen VK2BLQ for alerting us to this. That is Jac Holzman of Elektra Records fame, pictured in a recent article in Rolling Stone:
https://www.rollingstone.com/pro/features/elektra-records-the-doors-jac-holzman-1074071/

The Rolling Stone caption says he is in his “home studio,” but we recognize it clearly as a ham shack.

Here is another article about Jac:
https://www.nytimes.com/2013/05/07/business/media/miss-the-music-of-the-doors-theres-an-ipad-app-for-that.html?ref=todayspaper&fbclid=IwAR38NEVLwrIA_2x4TQC6w6v68iE1Z51z9ZU_ty3njuSPRnWN7FESyU1H9bw

ARRL reports that his callsign was K2VEH.

Hey, Pete plays guitar. So does Farhan. Should we have our people call Jac’s people? Maybe do lunch?

Too Simple? Deficiency of the Lafayette HA-600A Product Detector?

I’ve been having a lot of fun with the Lafayette HA-600A receiver that I picked up earlier this month. Adding to the mirth, I noticed that on SSB, the signals sound a bit scratchy, a bit distorted, not-quite-right. (I’m not being facetious; this is an interesting problem and it might give me a chance to actually improve a piece of gear that I — as a teenager — had been afraid to work on.)

Before digging into the circuitry, I engaged in some front panel troubleshooting: I switched to AM and tuned in a strong local AM broadcast signal. It sounded great — it had no sign of the distortion I was hearing on SSB. This was an important hint — the only difference between the circuitry used on AM and the circuitry used on SSB is the detector and the BFO. In the AM mode a simple diode detector is used. In SSB a product detector and BFO is used. The BFO sounded fine and looked good on the scope. This caused me to focus on the product detector as the culprit.

Check out the schematic above. Tr-5 is the product detector. It is really, really simple. (See Einstein quote below.) It is a single-transistor mixer with BFO energy going into the base and IF energy going into the emitter. Output is taken from the collector and sent to the audio amplifiers. (A complete schematic for the receiver can be seen here: https://nvhrbiblio.nl/schema/Lafayette_HA600A.pdf )

I had never before seen a product detector like this. One such detector is described in Experimental Methods for RF Design (page 5.3) but the authors devoted just one paragraph to the circuity, noting that, “We have not performed careful measurement on this mixer.” The lack of enthusiasm is palpable, and probably justified.

A Google search shows there is not a lot of literature on single BJT product detectors. There is a good 1968 article in Ham Radio Magazine: http://marc.retronik.fr/AmateurRadio/SSB/Single-Sideband_Detectors_%5BHAM-Radio_1968_8p%5D.pdf It describes a somewhat different circuit used in the Gonset Sidewinder. The author notes that this circuit has “not been popular.”

To test my suspicion that the product detector is the problem, I set up a little experiment. I loosely coupled the output of a signal generator to the IF circuitry of the HA-600A. I put the sign gen exactly on the frequency of the BFO. Then, I switched the receiver to AM, turning off the BFO and putting the AM diode detector to work. I was able to tune in the SSB signals without the kind of distortion I had heard when using the product detector.

So what do you folks think? Is the product detector the culprit? Or could the problem be in the AGC? Should I start plotting a change in the detector circuitry? Might a diode ring work better?


HA-600A Gets a New Coat of Paint — After Almost 50 years!

The HA-600A that I picked up last week was looking kind of sorry. There was a lot of rust on the cabinet. Below is the before picture.
I’m not really into cabinetry or radio aesthetics, but it is amazing what a 6 dollar can of spray paint can do. Formula 409 also helps. I moved the light bulbs forward a bit to get more light on that Juliano Blue dial.

I am really enjoying this radio. It has brought back many memories. I think I got one for Christmas in 1972. I was 14. I got my Novice ticket on April 27, 1973 and made my first contact on July 19, 1973. For that first contact I was using an HA-600A and a Heathkit DX-40. Later I used the Lafayette with a Heathkit DX-100. The HA-600A was replaced by the far superior Drake 2B on April 11, 1974. So I used this receiver for more than two years.

Looking around inside this receiver (and following up with Google) I learned some more about it:
— It was made in Japan.
— The manual says it has a “mechanical filter” but in fact it has a Toyo ceramic filter. This may have been just an honest mistake by the folks who wrote the manual — maybe they didn’t understand the difference between the two types of filters.
— There is a big difference between the HA-600 and the HA-600A, mostly in the front end circuitry. The HA-600 has fewer amplifier circuits at the front end. This probably explains why the HA-600 I picked up did not seem to live up to my memories of my teen-year HA-600A.

The fellow who gave it to me tells me that it had belonged to the short-wave listener father of a friend of his.

I know we have a lot of tube-type receivers that are much older than this thing, but I still think it is pretty amazing that this is a receiver that I used almost half a century ago. And it is still as good as new.

Mike WU2D’s Great Drake TR-3 Refurb Video — Part 2

Mike WU2D made another very nice video about his Drake TR-3 refurb.

He cracked me up when he noticed that one of the calibration oscillators was 30 Hz off. “Let’s pretend we care,” said Mike. Indeed. But it was probably wise to tackle this problem, given how upset modern hams seem to get with 30 Hz discrepancies. Mike noted that the problem was casued by “aging cystals.” Yikes! Another thing to worry about, along with the Southern Magnetic Anomaly.

Once again Mike has added a useful term to our lexicon: “The Dribble Method” of signal injection (or extraction): Just wrap a few turns of insulated wire around the tube or IF can and inject or measure away.

 Neutralization! Now there’s a blast from the Thermatron past. I haven’t done that in a long time. I liked Mike’s “reverse neutralization” method.

Mike’s video featured some real Boatanchor eye candy. That Heathkit HR-10 receiver caught my eye, as did that HP signal generator.

Thanks Mike. One hand behind your back OM.

WU2D’s TR-3 — Mike Refurbishes a Nice Old Drake Transceiver (PART 1) (Video)

There is a lot of Tribal Knowledge in this video. And good discussion of the many moral issues faced by those of us who work on old gear.

— Mike seems apologetic about his blatant and blasphemous spray painting of the Drake copper chassis. As well he should be.

— His stubborn replacement of the tube socket (to allow for shielding) seems wildly reckless to me. The Radio Gods may retaliate with some unexpected instability in that circuit.

— He CORRECTLY refers to the rewiring of the final circuity (to accomodate 6146s) as “the evil thing.” Indeed.

— I love in the beginning how he is listening to some ham radio chatter and the guy is talking about the selection of COM PORTS. With old radios “we don’t have COM PORTS — we have an antenna connector.” Well put Mike.

— I was struck by how much the TR-3 innards look like my 2-B receiver. But the TR-3 has no dial strings. That is a major technological improvement. And it has a PTO. Was this a case of Collins envy?

 — Mike adds a useful word to the lexicon: “shotgunning” — the indiscriminate replacement of entire categories of parts in old radios. Now I don’t mind shotgunning the electrolytics (some people bitterly oppose this). But I agree with Mike on the wisdom of keeping the paper caps in there.

I am looking forward to Part II. These videos are like “This Old House” but instead “This Old Rig.” And I will go back and look at Mike’s video on the Power Supply refurb. Thanks Mike.

Radio Schenectady

A while back I posted a picture (see below) of the shortwave dial of an old receiver used by my wife’s grandfather. I noted the odd presence of ‘Schenectady” among the exotic foreign locations on the dial. Pete immediately connected the dots by noting that Schenectady was the home of General Electric. This week Chris Waldrup KD4PBJ sent us a great web site describing the shortwave stations in Schenectady. Check out the tube that runs 100 kw AM (Big Bertha).

https://www.radioworld.com/news-and-business/schenectady-shortwave-transmitters-1941

 Chris also sent information about BIG AM broadcast band stations:

In addition to Schenectady being home to GE it is the city of license to clear channel AM 50 kW WGY 810. WGY was started by GE so if the radio was GE it was probably a way to promote their station at the time. I heard mention of Rochester too and that would be for 1180 WHAM another 50 kW clear. Both WGY and WHAM are still there going strong banging out their 50 kW.

 And Pete reminded us of KDKA, describing its long-lasting impact on one of his ears:


Let us not forget KDKA in Pittsburgh at 1020 which I think is no longer clear channel. I used to listen to KDKA on my crystal set when I went to bed at night. My bed had an exposed bed-spring which was my antenna. To this day there is a slight kink in one of my ears where my Brush headphones rested –I am a side sleeper.