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Re: [Amps] plate bypass caps

To: "Bill K0ZL" <k0zl.ham@gmail.com>, <amps@contesting.com>
Subject: Re: [Amps] plate bypass caps
From: "Carl" <km1h@jeremy.mv.com>
Date: Tue, 20 Jan 2009 21:56:19 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
I cant think of any postage amp micas that will handle over 2kV, most 
are much less, typically 500V.

Since the early style SB-220 grid bypass caps and the 80M fixed loading 
cap are known failure items as silver migration causes a breakdown, Id 
be leery of using them in anything.

Heck, I had to replace 3 of them in an old receiver 2 weeks ago.

Carl
KM1H


----- Original Message ----- 
From: "Bill K0ZL" <k0zl.ham@gmail.com>
To: <amps@contesting.com>
Sent: Tuesday, January 20, 2009 9:30 PM
Subject: Re: [Amps] plate bypass caps


>3 or 6 KV ceramics sold by RF Parts work best for plate bypass;
>
> However for other apps, the old postage stamp micas will work fine.
>
> I tested a whole bagfull of these things and they were all within one 
> or two
> percent of their ratings.
>
> Bill K0ZL
>
> ----- Original Message ----- 
> From: <amps-request@contesting.com>
> To: <amps@contesting.com>
> Sent: Tuesday, January 20, 2009 10:00 AM
> Subject: Amps Digest, Vol 73, Issue 29
>
>
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>> Today's Topics:
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>>   1. Re: plate bypass caps (Roy)
>>
>>
>> ----------------------------------------------------------------------
>>
>> Message: 1
>> Date: Tue, 20 Jan 2009 10:49:12 -0600
>> From: "Roy" <royanjoy@ncn.net>
>> Subject: Re: [Amps] plate bypass caps
>> To: <amps@contesting.com>
>> Message-ID: <4595D5891B17410A9F0A9ACEE5DD9674@RoyPC>
>> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
>> reply-type=original
>>
>> About,
>>
>> "I have quite a few of the old-style transmitting mica caps (C-D, 
>> Sangamo,
>> Solar, etc.).  Are these okay to use in a nearly-legal-limit amp for
>> either
>> plate-choke bypassing, or antenna load padders?  (etc.)"
>>
>> In at least one edition of my Editors And Engineers Radio Handbooks, 
>> it
>> stated that mica caps are not suitable for HV bypass application 
>> service
>> because of "dielectric molecular migration."
>>
>> I presume someone did not simply make this up. There must be basis 
>> for
>> such
>> a flat warning statement.
>>
>> 73,  Roy,    K6XK
>>
>>
>>
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