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Showing posts with label Old radio. Show all posts
Showing posts with label Old radio. Show all posts

Thursday, January 18, 2024

Some Great Reading Material -- Links to Radio Publications

 


My fellow Hambassador Dave WA1LBP sent this to me today (from Taiwan, I think).  Lots of great  ham radio and SWL info in these many publications.  The one that caught my eye was "The Modulator,"  an ARRL publication done by the 2nd District in the 1920s.  Really interesting.  I will sent this to Lyle, W7QCU who has an interest in radio from this era.   


Thanks Dave!  73! 

Thursday, November 16, 2023

The Grid Leak Detector -- Follow-up from Yesterday's Post on the Whole Earth Catalog's "Hippy" One Tube Receiver

Click on image for a better view
When I first looked at it in the Whole Earth catalog circuit, I thought it was a regen.  But a commenter correctly questioned this conclusion.  I remembered the grid leak circuit (WN2A provided more info in the comments).  This morning I found a Wikipedia page that explains it all very well.  I especially like the description of how this detector works both with small signals in the "square law" range of the tube, and with larger signals in the linear range of the tube.  The history of the discovery of the need for the large resistor is also very interesting.  I remember building FET amplifiers and finding that they would -- after time -- shut down.  This would happen as charge built up on the gate.  I had neglected to include the normal 100k ohm resistor (that would "leak" this charge to ground).  Once I put this resistor in, the amp worked fine.  

Here is the Wikipedia article:  


Sunday, October 15, 2023

Spy Rigs, Para Sets, Bugs, and Enigma Machines -- Dr. Tom Perera W1TP (video)


This is a really amazing presentation by Tom Perera W1TP to the Fairlawn (NJ) Amateur Radio Club. 

There is so much great info in this presentation.  Some of the highlights for me: 

-- The U.S. Civil War telegraphic (wired) spy set was just mind blowing.  I had never heard of this.  

-- The way the Nazis transmitted a signal 1 kc off the BBC frequency, so that Germans who tuned their Nazi-issued receivers to the BBC could be detected by neighbors (from the resulting 1 kc tone!) and turned in to the Gestapo.  

-- "Things don't land gently when dropped by parachute." Indeed.  This was a reminder of the courage of the young women who parachuted into Nazi-held territory during WWII.  Like Paulette.  It was great to see her with her Paratrooper wings on.  AIRBORNE!  And the picture of the operator with the bicycle generator was of Virginia Hall.  See: https://www.npr.org/2019/04/18/711356336/a-woman-of-no-importance-finally-gets-her-due  That portrait hangs in the hallway of the National War College. 

-- How they put the schematic of the PRC-5 right into the box.  Great idea.  But it had a terrible receiver.  One of the schematics showed a 455 kc IF and a BFO.  So they sent in superhets, not just regens. 

N2CQR operating the Para Set of G3ROO around 2009

This video makes me want to build a Para Set. 

Thanks a lot to Tom W1TP and the Fairlawn ARC. 

Thursday, September 28, 2023

A Look at Old Radios in Australia (video)

I thought you guys would like Peter Parker's latest video.  And in it, Dean KK4DAS might see a clue or two for his Halli restoration/repair project.  

What really struck me was the dial markings on the Australian radios.  They seem to be mostly oriented toward the reception of Australian AM or LW broadcasters -- not many exotic DX locations are marked.  Australia is big! 


Looks like a lot of crystal detectors in glass tubes.  At first I thought they might have been coherers, but I think they are crystal detectors. 

Many variometers visible. 

I saw one Geloso-Milano Communications 8 receiver.  Va bene! 

I also saw one "Tasma 780" Superhet.  Cool name! 

What is up with the "Green Theme"? 

I have some of the headphones they showed. 

Please note in the Comments section anything special that you noted in watching Peter's FB video. 

More on the coil winding machine here: 

Saturday, August 19, 2023

Valveman -- The Story of Gerald Wells


Don't be deterred by the annoying test patterns at the start of this video.  Just skip past them.  The rest of the video is quite good.  Or you could just click on this link and avoid the first 83 seconds of test pattern:  https://youtu.be/Y8w6iwaAGJ4?t=83

Gerald Wells has been mentioned on this blog before, but I don't think we've ever presented the full documentary on this fellow.  Here it is.  Gerry is clearly one of us: a radio fiend, obsessed (as he admitted!) with wireless, a victim of THE KNACK.   

George WB5OYP of the Vienna Wireless Society got to meet Gerald Wells and visit his museum. George alerted me to this video.  Tony G4WIF also was able to visit Gerry and his museum. 

The documentary is full of interesting stuff, and is, in itself, a Knack Story.  Wells mentions the Crippens murder so well described by Eric Larson in "Thunderstruck."  It was this crime that brought radio to the center of public attention.  

Tuesday, July 4, 2023

A Very Early Radio-Controlled Device -- Using Spark and a Coherer, in Spain


Click on the picture for a better view -- check out the coherer and the tapper 

Hack-A-Day has an interesting story about Leonardo Torres Quevedo and his very early automated chess machine.  Torres Quevedo was a Spanish inventor active in the early years of the 20th century. 

The chess device was really interesting, but two things caught my eye about this fellow: 1) he lived and conducted some of his experiments in my old home of Bilbao, Spain and 2) he built a very early radio-control system that used -- in the receiver -- a coherer as the detector.  

There is a lot material on Torres Quevedo.  Here is just a sample of what is out there  

His book:  https://www.torresquevedo.org/revistas/index.php/BIB/issue/view/12/1.  Discussion of the Telekino device is on pages 109-127. 

The Branly Tube or Coherer: https://en.wikipedia.org/wiki/Coherer

https://en.wikipedia.org/wiki/Leonardo_Torres_Quevedo

https://www.researchgate.net/publication/2998424_Early_Developments_of_Wireless_Remote_Control_The_Telekino_of_Torres-Quevedo

https://cyberneticzoo.com/wp-content/uploads/2010/12/Telekine-Yuste.pdf

1903 article in Electron (Spain) about the Telekino and Coherers. https://hemerotecadigital.bne.es/hd/viewer?oid=0028654330&page=6

https://alpoma.net/tecob/?p=13766   This article contains the diagram of the device (see above).  You can see the coherer with its tapper.  

Here we see the Telekino installed in a boat in Bilbao harbor.

Monday, May 1, 2023

Apex Surplus in Los Angeles


The Polaroid camera for the Tek 'scope was pretty cool.  And the comments about the Simpson 260 made me feel good about finding one at a recent hamfest, but I don't think mine is an extremely rare Model 2.   

Friday, April 28, 2023

Who is the Man in the Portrait in Artie Moore's Shack?

 


Who is this person?   He is in a prominent position in Artie Moore's very early radio shack.  Artie was obviously big on labeling things, and there is a label under the picture but I can't make it out.  What do you folks think?  Who is this?  

Monday, April 24, 2023

Four Old BBC Shows on Radio: Hams, Physics, and Antique Wireless


The first one, about ham operators in general, is pretty depressing. Then it goes downhill as they shift to those who are listening to baby monitors and cell phones.  Yuck. 

The second one seems to show some physicist having understandable difficulty explaining particle-wave duality in a short TV segment.  

There is a short bit (that I didn't quite get) about the BBC's "Teddy Bear's Picnic."  

The final one is about Gerald Wells and his Antique Wireless Museum in South London.  Note the white coat -- clearly a boffin.  For a while I confused him with Rupert Goodwins G6HVY (similar white coat, but a different bloke).  

Thursday, February 23, 2023

Early (1912?) Ham Station

 
Perhaps a bit overdressed by today's standards, but he's got a familiar look on his face.  Confidence and pride in his rig, and a steely determination to make contacts with it.  

If you zoom in you can see the crystal and the cat's whisker. 

More on this here: 

http://uv201.com/Photo%20Pages/ham_3.htm?fbclid=IwAR10Lbi2CAsYeiBDUjWb5KIQrh1SJVGwDyL2_1ZrkPk1VbllAUbeahwxsAI

Sunday, February 12, 2023

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!  

Saturday, February 4, 2023

To Re-Cap or Not to Re-Cap -- Curious Marc on the Electrolytic Controversy in Ham Radio


A while back I got some fairly acerbic feedback when I DARED to suggest that perhaps it would be a good idea to replace the old electrolytic capacitors in ham radio equipment.  It was as if I had attacked motherhood and apple pie!   

Yesterday I was looking at CuriousMarc's YouTube channel and I came across the above video.  While I had been in the preemptive replacement camp, Marc makes a good case for leaving some of the old caps in place.   The fact that the electrolytics usually are open when they fail, and that there are fuses in the power supply to protect the transformers,  are important points.  His admonition not to replace electrolytics with tantalum caps (which fail closed) was also very useful. 

OK, my flame-proof suit is on! 

Wednesday, February 1, 2023

Hammarlund HQ-100 Misidentified in 1963 FCC Film


Oh the indignity!  It appears at 7 minutes 16 seconds in this FCC film.  It is clearly an HQ-100, but the FCC subtitles identify it at an HQ-110.  It is clearly an HQ-100 ( the model without the clock). 

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

As the owner and operator of what must be one of the few remaining HQ-100s, I feel obligated to defend the reputation of this fine piece of shortwave gear.   

How many of you have HQ-100s?  


Saturday, January 28, 2023

Hugo Gernsback -- Was he Like Wayne Green?


"The Electrical Experimenter" sent to me by Nick M0NTV reminded me of Hugo Gernsback.  Many of the radio books I have on my shelf have his name on them.  He played a big role in early radio and television, and in science fiction. Check out the Wikipedia article on Gernsback:  

I see similarities between Hugo Gernsback and Wayne Green.  What do you guys think?   

Gernsback's TV goggles in 1963 

That's Gernsback watching TV in 1928

Tuesday, January 10, 2023

SolderSmoke Re-Play: Shep tries to build a Heising Modulator -- Shep on Parasitics and Troubleshooting: "That way madness lies"


You guys really have to listen to this.  This is culturally important.   

In this 1965 radio broadcast, Jean Shepherd describes his teenage struggles with parasitics and other technical problems in his homebrew 160 meter transmitter.

He describes the sound of parasitics on a signal, saying that they sound as if the signal is being attacked by "debauched erotic locusts."

He really nails it in describing the scornful, dismissive tone that many hams use in telling their fellow radio amateur that there are problems with his signal. ( I have recently been on the receiving end of this kind of treatment.)

He observes that no one is more worried, "than a man who has built something and can't get it to work." Indeed.

During a date with a girl from his high school, he is so obviously preoccupied with his transmitter trouble that she tells him that something is wrong with him and that his mother "should take him to a doctor."

And he describes the joy that comes when you figure out the problem and get the thing to work.

The REALLY good stuff begins at about the 25 minute point.

http://ia310115.us.archive.org/2/items/JeanShepherd1965Pt1/1965_01_29_Ham_Radio.mp3

Shep was quoting from King Lear: "O, that way madness lies; let me shun that; No more of that."  In other words: "BASTA!"  

EXCELSIOR!

Wednesday, December 14, 2022

Faust Gonsett and the SB-33 in 1963

 
Click on the images for better views

When this ad appeared in 73 Magazine in February 1963 I was 4 years old, living on Manhattan Island.  Pete N6QW was in the Navy, heading to Midway Island. 

Pete writes: 

-------------------
This ad has a tremendous impact on the foundations of our hobby. The SBE-33 was pure genius in its design and implementation.

  1. It is a hybrid rig using Germanium transistors –the transistor was only 15 years old
  2. The Mechanical band switching showed the strong use of mechanical assemblies
  3. The small size was simply amazing
  4. The Bi-lateral circuitry predates any Bitx circuits.
  5. The urban legend was that a team of illuminati were involved in its design (Don Stoner is one name that pops up)
  6. The Japanese were a quick study and the FTdx100 in 1967 is a result, only better.
  7. Many are still around in shacks. I have three

 

Gonset was well known for innovative designs – the Gooney Box is another example. Look at all of his compact mobile equipment.

 

The next point – the final owner of SBE was Raytheon thusly the next generation of SDR Radio Equipment for the US Air Force can trace its pedigree to the SBE-33.

 

This was the appliance box of 1963. I saw my 1st SBE-33 (August 1963) when likely you were in the 2nd Grade and I was headed off to Midway island.

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

 


I have an SBE-33 that N6QW sent me. Thanks again Pete!

Also, I'd like to note that W6VR had a very cool name.  Faust Gonsett.  I just sounds like the name of a real radio guy.  Google says this of the given name Faust: 

"Faust as a boy's name is of Latin origin, and the meaning of Faust is 'fortunate, enjoying good luck.'   Indeed. 

Friday, December 9, 2022

R-390s, KWM-2s, Airplanes, and Magnetic Loops -- A Really Interesting Interview with Ted Robinson K1QAR


Eric Guth 4Z1UG has a really interesting interview with Ted Robinson K1QAR.  

I really enjoyed hearing Ted's inspiring story: 

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

https://www.qsotoday.com/podcasts/K1QAR

Listeners will like the discussion of the R-390 and the KWM-2.  And his talk about airplanes.  And the joy of repair.  



Here is Ted's QRZ.com page:  https://www.qrz.com/db/K1QAR

Thanks Eric!  Thanks Ted! 

Saturday, September 10, 2022

The Cure for Frequency "Bunching Up" in Analog LC VFOs -- It Is Not So Simple. But we have a good calculator. Comments sought!

Bob's calculator shows good tuning linearity with an ordinary SLC capacitor 

One of the complaints about analog LC VFOs is that they have non-linear tuning -- when you turn the dial (usually attached to a variable capacitor) the space between frequencies is NOT constant.  This is especially apparent at the high end of the frequency scale where frequencies (and stations) appear to be severely bunched together, making tuning difficult.  This problem contributes to the defection of some great homebrewers:  They give up on LC VFOs and they switch to digital VFOs.  Sad. 

But there is hope:  Not all LC VFOs tune this way.  Even on rigs from "back in the day," back when the Si5351 hadn't even been thought of,  some LC VFO rigs tuned linearly.  My beloved Drake 2-B and my almost equally beloved HT-37 are good examples.  How did they do this?  How did they escape the dreaded "bunching up?"  

For a while, I thought that it might have had to do with the use of the series tuned Clapp circuit.  But on further noodling, this didn't seem to make much sense. 

Then -- like others -- I thought that it  must be caused by the adroit use of special capacitors. You see, in ordinary variable capacitors when you turn the dial, the capacitance increases linearly.  But in the LC circuit, frequency changes as the inverse of the square of the capacitance. Thus the bunching up. So the solution must come from the use of the special capacitors that compensate for this, that -- because of the shape of their plates --  produce linear tuning.  With these variable caps, frequencies on the dial are spaced out nicely, there is no bunching up. Great right?  

From Terman, Radio Engineers Handbook, 1943, page 123

Over the years, many hams have jumped to the conclusion that rigs with good tuning linearity MUST be using these special caps. For example, in 2013 a ham posted in the Antique Radio forum this message: 

There are three types of open, variable plate caps;
SLC= straight line capacitance where the capacitance varies linearly,
these are the most common and have half-circle plates
SLF= straight line frequency where the plates are tapered to allow
for linear tuning of the frequency
SLW= straight line wavelength, you get the idea...

SLF and SLW caps have oblong plates.

The effect on tuning a receiver can be dramatic. One example is the
Hammarlund SP series of receivers where the ham bands are very
compressed at one end of the tuning range. They used SLC caps
in the VFO. On the other hand rigs like the Kenwood TS-520
and FT-101 series have linear tuning across each band. These use
SLF variable caps. Most old 1920's battery radios used SLW
where stations were identified by their wavelength.

Well, not really.  

-- I now have several VFOs from the extremely linear-tuning FT-101.  But when you open them up to look at the tuning capacitor, it is NOT a Straight Line Frequency capacitor.  

-- Many of us over the years have built VFOs that are quite linear in their tuning without resort to these special capacitors -- we did it with ordinary Straight Line Capacitance caps.

-- When you look at the "How to build VFO" literature in the ham radio books, you see a lot of good recommendations about using solid, brass-vaned caps with ball bearings at either end.  But never do you see circuits that require the use of SLF or SLH capacitors. If they were the key to tuning linearity, we'd see them mentioned in the literature. But we don't.   

So where does the linearity -- or bunching up -- come from?  

The answer comes to us from a really neat calculator from Bob's Electron Bunker: 

http://electronbunker.ca/eb/BandspreadCalc.html

This calculator allows you to select your frequency range, and the tuning range of your variable cap. It then displays for you what the tuning range will look like on your dial.  You can see if there will be bunching up, or if the frequencies will be nicely spread out.  And -- and this is the really cool part -- you can then specify if your capacitor is SLF, SLW, SLC or Midline-Centerline.  This really illustrates the effect of the different capacitor types. 

I used Bob's calculators to do some experiments with various types of capacitors, various frequency ranges, and various combinations of trimmers and padders.   You can see what I did here: 

http://soldersmoke.com/VariableCapsSLCSLF.pdf

One important thing to keep in mind:  The SLF caps were made for AM broadcast receivers that were tuning from 540 to 1600 kc.  That is a 3:1 tuning range.  Most of the time in HF ham radio, we are tuning across a much smaller range, say from 5 MHz to 5.5 MHz.   That is a 1.1:1 tuning range. In those cases where we ARE tuning across a wide tuning range -- for example with a receiver covering 3-9 MHz, the SLF cap can help prevent the bunching up. 

But we can have fairly good linear tuning without resort to SLF caps.  Bob and his calculator point out that by narrowing the frequency range of interest, and by using either smaller range caps (ordinary SLC caps), or SLC caps with trimmers and padders, we can achieve tuning linearity.  And sometimes, when you have achieved this nice tuning linearity with a plain SLC cap, putting a fancy SLF cap makes tuning linearity worse. 

One piece of VFO tribal wisdom that is confirmed by all this:  It is better to use a smaller variable cap with a maximum capacity of about 30 picofarads. 

I think we should spend as much time focusing on VFO tuning linearity as we do on VFO frequency stability.  Bob told me that in the old days, the calculations for various tuning linearity scenarios were difficult.  But now we have Bob's calculator.  When building a VFO, just use Bob's calculator, plugging in the numbers to get a preview of what your tuning linearity will be like. If it is bunched up, you can play with the trimmer and padder values to achieve the tuning linearity you desire.   


Thanks to Bob of Bob's Electron Bunker for this great calculator. 

You can see another discussion of "bunched-up" tuning in the comments section of this article: https://www.nutsvolts.com/?/magazine/article/may2015_Whipple

What do you folks think of this?   Please put comments below. 

Monday, September 5, 2022

Why Do Some VFOs Tune More Linearly Than Others?

This has been one of the major complaints about our beloved analog LC VFOs:   The frequency tuning on these circuits is often not linear.  For given amount of VFO frequency dial turn you can get vastly different changes in frequency.  At one end of the tuning range the frequencies are nicely spaced and tuning is easy.  But at the other end of the tuning range all of the frequencies are bunched together.  This is one of the problems that leads some homebrewers to defect to the sad land of "digital VFOs." 

But wait.  It appears that the old designers found a solution to this problem.  Just look at the tuning dial of my HT-37.  The frequencies are all spaced out evenly.  How did they do that? 

I had been thinking that this success may have resulted from Hallicrafters' engineers using the series-tuned Clapp circuit.  Here the main frequency determining element is a series-tuned LC circuit and not the parallel tuned LC circuit that we see in the more commonly used Colpitts circuit.  

But hold on -- how could that be?  The frequency bunching problem that we attributed to the Colpitts circuit must also exist in the Clapp, right?  I went back to SSDRA where there was a good discussion of Colpitts and Clapp VFOs.  The advantage of the Clapp was said to be in its use of a larger value coil which helped minimize the effects of stray inductances.  But there was no mention of the Clapp offering improved linearity in tuning.  

I have in front of me two transceivers:  The Mythbuster uses a 9 MHz Clapp circuit (see below).  The 17-12 rig uses a Colpitts Circuit.  I checked the tuning linearity of both.  Both appeared quite linear in tuning, with no real difference between the two.  

Then I looked at the tuning capacitor in the Mythbuster 17-12 rig.  It came out of an old Hallicrafters transmitter, probably the HT-44.  I looked closely at the stator and the rotor plates.  Both are curved.  I'm guessing that this may yield a more constant change in capacitance for a given movement of the main tuning dial.  

Next I opened up the VFO on the Mythbuster.  (It is the VFO from an old Yaesu FT-101.)  I couldn't see the stators very well but it appears that their shape is different from the square shape we often see in variable capacitors.  Could it be that this variable capacitor was also made to provide linear tuning?  

Back in 2013 Norm Johnson wrote about all this in the Antique Radios.com forum: 

A capacitor that has uniform increase in capacitance with rotation will have the stations at the high end of the band squeezed together. Another type known as the straight-line frequency variable capacitor has, as you might guess, a characteristic that gives even spacing of frequencies with shaft rotation. These were popular in the 1920's but weren't very good for superhets where you needed to have a dual section capacitor that would tune both the RF and local oscillator, and have them track each other properly. The midline variable capacitor is more compatible with a superhet, and easier to make both sections track properly. This is the type that you see in most receivers from the late 1930's to the end of the tube era. They don't have quite the equal spacing between stations across the band that the old straight-line frequency caps had, but they're much better than the variables that change capacitance linearly with rotation.

I wrote an online calculator that helps in the design of the tuning. It shows what frequency range you'll get with a specific type of variable capacitor, including the effects of padder and trimmer capacitors. It also displays a dial scale that shows how the frequencies are lined up accross the dial.
http://electronbunker.ca/eb/BandspreadCalc.html

Steve W6SSP also provided some really good info back in 2013: 

There are three types of open, variable plate caps;
SLC= straight line capacitance where the capacitance varies linearly,
these are the most common and have half-circle plates
SLF= straight line frequency where the plates are tapered to allow
for linear tuning of the frequency
SLW= straight line wavelength, you get the idea...

SLF and SLW caps have oblong plates.

The effect on tuning a receiver can be dramatic. One example is the
Hammarlund SP series of receivers where the ham bands are very
compressed at one end of the tuning range. They used SLC caps
in the VFO. On the other hand rigs like the Kenwood TS-520
and FT-101 series have linear tuning across each band. These use
SLF variable caps. Most old 1920's battery radios used SLW
where stations were identified by their wavelength.
Steve W6SSP

These two variable caps came out of my junkbox.  Both are Eddystones, made in England.  My guess is that the one on the left is SLF.  But could the one on the right (out of an old regen) be SLW?   

The Drake 2-B also has perfectly linear tuning.  I looked at the manual:  "The tuning condenser is of special design..."   I'm guessing that they used an SLF variable capacitor. The 2-B had no need for ganged capacitors -- the "preselector" was tuned via a separate front panel control. 

I looked at the tuning dials on my Hammarlund HQ-100 receiver.   It is fairly linear in its tuning, but not as linear as the HT-37 or the Drake 2-B; on all of the tuning ranges the frequencies seem to spread out a bit at the lower end.  My guess is that Hammarlund used the midline variable described above by Norm Johnson.  The HQ-100 did use a ganged variable cap, with one section tuning the RF amplifier and the other tuning the local oscillator. 

Mythbuster on the bottom.  17-12 rig on the top


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