{Collins} Re: 75A-4 help reversing mod/repair



At 02:03 PM 7/25/2004 -0400, you wrote:
... there was B+ on the filter input (zap--ouch!).
>  ...  In this scheme, it looks like V5's plate is fed
>*through* the input coil of the mechanical filter!
>(1) Anyone see this before?

Chris,

If by "this" you mean the B+ being fed through the filter(s). Yes. It's 
normal on at least the early receivers.

>   I'm just wondering if it's a standard mod,

Howard Mills normally removes the B+ from the filters when he overhauls a 
radio, as do many other people as far as I know.  It is a very good 
idea.  I don't have my copy of "The Compendium" with me, but I seem to 
remember at least one of the articles in it details this mod.  If you don't 
have "The Compendium" I suggest you get one.  You can download the SB's and 
SIL's from:
<http://www.collinsradio.org/html/servebull.html>

(sorry, can't help with other questions because I don't have any manual or 
radio at hand.)

>(3) Where is the filter socket pin 1 "bus" ground point supposed to be?

I seem to remember that the ground(s) for the filters are mentioned in the mod.

Roy

- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
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