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defective vibrator units




 
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« on: May 29, 2019, 09:13:37 PM »

I have 3 DY88 power supplies for the AN/GRC9. Today I tested the 2 spare units, and none worked, failing 105 V. So I opened them and they actually were brand new inside, with spare vibrators and iron hydrogen valves. So I tested the spare vibrators and also these did not work. So I opened them up and measured the contacts Even when pushed together, no contact. The contacts were quite black. I think hat there is a material from the sponge rubber that does react with the silver. That a chemist may chime in  (silver sulphide?) So I did clean the contacts with  fine sand paper while pushing them together which solved the problem.
So if you have e nop vibrator, don't directly buy an other one. Also NOS vibrators can have this problem. Simply clean the contacts.
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W2PFY
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« Reply #1 on: May 30, 2019, 10:20:17 PM »

I think I remember that somewhere along the line, solid state vibrators were manufactured in the original looking cans. Am I dreaming or was this indeed a product?

Good going on your repair. I have some equipment with six volt vibrators. I guess to make them work off of modern power supplies, I'll have to use a high wattage low value resistor to drop from 12 volts?
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The secrecy of my job prevents me from knowing what I am doing.
PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #2 on: May 31, 2019, 11:13:42 AM »

using 12 V with a series resistor may be dangerous, than the voltage will depend very much at the consumption and may clime up too much when receiving
There are small and very cheap DC-DC converters from China. For a few bucks you can drop 12 V to 6 Volts at 10 amps or so. They are current limited and most are short circuit proof. But you have to put then inside a tin can with feed-through filters for the noise which is a hassle.
But a  10  V zener and a power FET as source follower will do as well. That gives you approx 6 - 7 Volts Only generates a little heat
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WD5JKO
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WD5JKO


« Reply #3 on: May 31, 2019, 11:08:36 PM »


You might find this of interest:

https://youtu.be/E8dHik39FIU
http://radio.pekorf.com/RVB1_Intro.html

"You own a nice piece of vintage equipment, maybe perfectly restored, but without means to
keep it running anymore! What is a vintage radio aficionado to do to keep his or her vintage tube equipment running?
The answer: Our PeKo RVB-1 solid-state radio vibrator board. This board was specially designed by us to replace a wide variety of radio vibrators, WITHOUT the need of any modifications to your vintage equipment. The RVB-1 solid-state vibrator board is designed to be a direct drop-in replacement to many different mechanical vibrators."

Jim
Wd5JKO
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PA0NVD
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Nico and Chappie (Chappie is the dog...)


« Reply #4 on: June 01, 2019, 01:47:56 PM »

That's a nice solution Jim. Thenks for the links. I did not know that these boards did exist. Indeed the site states that it is the sulpher from the sponge rubber that gives the problem.
 I made a solid state one a few years ago using a 4047 Cmos to drive two mosfets. Very simpel and not even 5$ worth of materials. . I don't think that these boards were available by than. It is still working in a vibrator unit for a 1938 car radio. But when I want one of those boards here in Costa Rica, it will cost me at least 60 - 80 $ including import, duty etc.  I consider that a little expensive, but that true for many imported materials in CR.
I did clean the contacts of a vibrator for the GRC9 about 30 years ago, and it still works perfectly. That was 30 minute work and saved me the cost.
Yesterday I cleaned all spare ones I had (NOS) and they all work fine . Cleaning is still a lot less work than going solid state
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W6TOM
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« Reply #5 on: June 04, 2019, 05:07:51 PM »

  In the May 2017 issue of Electric Radio is an article by N6CAV on rebuilding a DY-88 vibrator using an Aurora Designs vibrator module, the modules are not cheap but work very well. I did the photos for the article and have converted a few of the DY-88 vibrators with good results.

  Email me and I can provide a source for the modules in California.

   W6TOM


* G.JPG (183.61 KB, 826x768 - viewed 81 times.)

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Patrick J. / KD5OEI
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« Reply #6 on: June 05, 2019, 01:26:13 AM »

Here are six circuits for solid state vibrator replacements.

* solid state vibrators info.pdf (1805.63 KB - downloaded 63 times.)
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