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Title: Viking II CDC Post by: W9BHI 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 Title: Re: Viking IICDC Post by: W9BHI 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 Title: Re: Viking II CDC Post by: ve6pg on June 05, 2012, 03:58:36 PM ...where in the archives?..i'd like to see it..
..tim.. ..sk.. Title: Re: Viking II CDC Post by: W9BHI 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 Title: Re: Viking II CDC Post by: KM1H 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 Title: Re: Viking II CDC Post by: kb3ouk on June 05, 2012, 06:34:27 PM http://www.eham.net/ehamforum/smf/index.php?topic=12735.0 (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. Title: Re: Viking II CDC Post by: KA0HCP on June 05, 2012, 07:13:34 PM The technical term for that is "Armageddon Audio Quality".
Title: Re: Viking II CDC Post by: KM1H 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.
Title: Re: Viking II CDC Post by: ve6pg 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.. Title: Re: Viking II CDC Post by: WA1GFZ on June 06, 2012, 11:39:29 AM I left the 6J6 in and carefully adjusted it to give a little compression. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
The stinkonium rectifier was removed. I think it is pretty useless. |