[R-390] Capacitor Replacements Vitamin Q

[nryan at mchsi.com]

Hi, All,

On one or two decks I did wholesale paper cap replacement including Vitamin Q's, but quickly realized it's best simply to go after the BBODs and the potential mechanical filter killer cap, C553.

After pulling any VQ and testing it, I've found it good in each instance -- thus my remorse.  Orange Drops in lieu of BBODs are my choice despite the challenge of fitting them in.

73 de Norman, KG4SWM


----- Original Message -----
From: rbethman <rbethman at comcast.net>
To: r-390 at mailman.qth.net
Sent: Mon, 24 Jan 2011 13:55:48 -0600 (CST)
Subject: Re: [R-390] Capacitor Replacements Vitamin Q

BBODs, Tiny Chiefs, and similar are INDEED paper caps.

So are the brown postage stamp ones of old.

I haven't had a single Sprague Vitamin Q give me an issue.

Bob - N0DGN

On 1/24/2011 2:43 PM, Barry wrote:
> Aren't BBODs paper?
>
> Barry - N4BUQ
>
>
>   On Mon 24/01/11 11:26 AM , Tisha Hayes tisha.hayes at gmail.com sent:
>> A good rule to follow is to replace what is proven bad and leave the
>> restalone, unless you have good reason.
>>
>> Good reasons to replace capacitors;
>> 1) They are paper
>> 2) They are BBOD's
>> 3) They are way out of spec
>> 4) It is the "killer cap" on the mechanical filters
>>
>> Wholesale replacement may sound like a nifty idea but you can end up with
>> aradio that is seriously out of alignment if those caps are in the RF/IF
>> deck.
>>
>> I have tweaked with capacitor values in the audio section to improve
>> frequency response and done a few AGC mods to eliminate the "moment of
>> silence". Sometimes I change cap values in the B+ supply to reduce
>> ripple(Chuck Ripple , ).
>>
>> To a large extent, there is a similar set of rules for the wholesale
>> replacement of resistors.
>>
>> -- 
>> Ms. Tisha Hayes/ AA4HA