Yes Charles, I neglected to say, I did replace all old electrolytics
in the speech amp. The couplettes don't seem to be a problem. As I
remember- does the speech amp also have a compressor? That seems to work OK
as well, without distortion. Well the reason I used 1500 volts in the
modulator is because thats what I had available. The replacement was bad
and the maker would not make good on it- so mods
came into play. My intention was to keep it as original- but when the 816s
kept flashing, I found they are as rare as hens teeth. Too pricy for
something easily replaced. I have not run mine in several years also.
Neighbors complain- RFI big time. Another story.
73s Good luck Russ
From: Charles Ring W3NU <[EMAIL PROTECTED]>
Reply-To: [email protected]
To: [email protected]
Subject: Re: [AMRadio] Globe King
Date: Thu, 19 Sep 2002 15:11:36 -0400
russ dworakowski wrote:
> Charles, I have a 500B, that came to me as basket case. I ended up
with
> all new iron. Hopefully, yours was stored well, and not ina damp
> location. If so, it would be good to just fire it up and let it dry
out.
> Its amazing how much moisture those old open transformers
> soak up. When all said and done,my GK 500B, had changes in the
> modulator- A higher voltage on the plate transformer- 1500v. I put
neg. 5
> volts bias on the 811s. In the speech amp, I did not change anything.
I
> used a D104 mic and I got real good audio rpts. I also solid stated
the
> modulator power supply- the 816s kept flashing over,so bye bye.
Also
> switched to 3B28s in the RF power supply.
> Have fun! Russ
I have owned my 500A for 30 years but havent used it for maybe 15. It seems
to
have survived basement storage with all iron intact. It already has 3B28's
and
i can see that the 816's will be at least an inconvenience so they might
go. I
have a D104 and will try it before i modify the speech amp, but eventually
i
want to get rid of the couplettes and try a Shure SM5B and a broadcast mic
compressor left over from my years as a broadcast engineer. I am not
inclined
to trying to boost the modulation since i won't be in an Arbitron-driven
loudness war. I do see a number of very old original small electrolytic
caps in
the modualtor that probably should be replaced.
73 de W3NU
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