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Author Topic: Viking II CDC  (Read 5698 times)
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W9BHI
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« on: June 05, 2012, 11:17:54 AM »

I noticed something different on a Viking II CDC.
There is a diode in series with the secondary of the modulation transformer that goes to the final plate circuit.
The manual says it is a "high level negative peak limiter".
Is this one diode really an effective limiter?
If so, could this approach be used on a Valiant II?

Thanks,
W9BHI
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W9BHI
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« Reply #1 on: June 05, 2012, 02:45:28 PM »

I have since looked in the archived posts and this question has been asked and answered before.

W9BHI
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ve6pg
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« Reply #2 on: June 05, 2012, 03:58:36 PM »

...where in the archives?..i'd like to see it..

..tim..

..sk..
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...Yes, my name is Tim Smith...sk..
W9BHI
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« Reply #3 on: June 05, 2012, 04:17:37 PM »

I guess that I didn't see an exact answer pertaining to my question but there were alot of diode negative peak suppressor discussions for 1, 2, 3 and 4 diode types.
Sorry for the misunderstanding.
Maybe someone will still chime in on my original post.

W9BHI
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KM1H
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« Reply #4 on: June 05, 2012, 04:54:04 PM »

I removed that diode (its actually a big selenium) and completey rebuilt the audio chain in my CDC following a 1998 series of articles in ER Magazine. Havent bothered with any 3 diode peak clipping mods yet as it doesnt appear necessary.

Carl
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kb3ouk
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The Voice of Fulton County


« Reply #5 on: June 05, 2012, 06:34:27 PM »

http://www.eham.net/ehamforum/smf/index.php?topic=12735.0
Here it says the Viking II CDC was built with the negative peak limiter and also had a type of modulation AGC to make it easier for non-experienced operators to use in an emergency. So I guess that meant that during an air raid or something, the receiving end could still understand the frantic op that was screaming into the mic.
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KA0HCP
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« Reply #6 on: June 05, 2012, 07:13:34 PM »

The technical term for that is "Armageddon Audio Quality".   
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KM1H
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« Reply #7 on: June 05, 2012, 10:30:15 PM »

It sounds like it in stock config which is why I ripped the diode and 6J6 circuit out. The 115VAC PTT relay is also loud and clunky but after replacing the 2 tiny seleniums and the filter cap it works OK for now. I may change it to what I did to the Viking I.


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ve6pg
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« Reply #8 on: June 06, 2012, 08:40:05 AM »

..i was thinking abt removing/changing caps, as well as the 6j6 circuit......what are the values of the resistor, and cap, off of pin2 of the mic connector?..

..sk..
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WA1GFZ
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« Reply #9 on: June 06, 2012, 11:39:29 AM »

I left the 6J6 in and carefully adjusted it to give a little compression.
The stinkonium rectifier was removed. I think it is pretty useless.
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