[AMRadio] Screen bypass caps (was DX-100B on Phone - bad audio distortion /oscillation)

[Bernie Doran]

I just found that the built in screen bypass caps failed on a pair of Eimac 
4cx250 sockets, one was full open the other flipped back and forth, on and 
off at about a 1 second rate. Nerver saw anything like that before.
----- Original Message ----- 
From: "Jim Wilhite" <w5jo at brightok.net>
To: "Discussion of AM Radio in the Amateur Service" 
<amradio at mailman.qth.net>
Sent: Thursday, December 15, 2011 10:55 PM
Subject: Re: [AMRadio] Screen bypass caps (was DX-100B on Phone - bad audio 
distortion /oscillation)


> They tend to change value due to poor contact of the lead to the silver 
> plates, then eventually open.  I have never seen an open one but have seen 
> them with flakey contacts internally, causing circuits to misbehave as you 
> are experiencing.
>
> Also some of those pink ones are paper.  If they have the six dot 
> identification system, with the arrow pointing right, thirst dot top-left 
> will denote paper or mica.  There are two colors, white and black, check 
> any old handbook for the legend.
>
> Rick Poole <wa1rkt at arrl.net> wrote:
>
>>At 08:47 PM 12/15/2011, L L bahr wrote:
>>
>> >>>>>
>>>Not true.  Silver micas have "silver migration", over time.
>><<<<<
>>
>>OK, but then wouldn't that mean they would short rather than open?
>>
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