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[AMPS] shielding

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Subject: [AMPS] shielding
From: (Jon Ogden)
Date: Sun, 3 Oct 1999 23:01:25 -0500
Clinton Herbert wrote:

>> Gentlemen,
>> Seeing the post on the four 3-500z's has prompted me to ask a question I
>> have been wondering about.  I also have a amp that runs four 3-500ZG's BTW
>> I have never run it over legal limit Pat, will your car go over the speed
>> limit????  Anyway I would like to cut the top of the amp out and install a
>> piece of Lexan in its place to view the tubes when they are lit up.  Any
>> pro or con on this?????
>> Larry K0AEY
> Wouldn't that put yourself, and your eyes to risk? I believe that there's a
>reason why high-power amplifiers have metal shielding. Perhaps I am wrong on
>this one, but you still won't catch me staring inside of an amplifier when it
>is transmitting.

Amps aren't shielded with metal shielding to protect your eyes!  They are 
made of metal primarly for the purposes of strenght and RF grounding.  
The filaments in a tube are dimmer than a lightbulb.  You could look at 
them for hours without harm.

My 4-1000A amp has a nice lexan cutout in front that allows me to see the 
nice glow of the tube when keyed.  Really cool!

Regarding Larrys question on the Lexan, it might be OK, but yet it could 
end up creating some RFI problems due to the lack of the shielded cover.  
Additionally, it could cause instability in the amp.  Many times the amp 
cabinet be some sort of a resonant structure for the tube at its anode 
resonant frequency.  The cover could be part of the amp design.

Short of those two things, if replacing the cover with lexan doesn't 
cause either of those two problems, go for it.  I had some stability 
issues with my 4-1K amp when I put the cover on and was about to replace 
the metal cover with lexan.  Solved the problem though!



Jon Ogden
KE9NA    <--- CHECK IT OUT!  It's been updated!!!!!

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