{Collins} Re: 75A2 Schematic



Gary -

I have a Sam's Photofact on the 75A-2 with a schematic showing the 6BE6 
mixers.  It is Folder 4 of Set 171, dated 6/52.  I also have a QST 
article from July 1955, written by Collins engineers E A Andrade, W0DAN 
and E W Pappenfus, W0SYF, which discusses "updating" the 75A-2 design 
"three and one half years" after it's original design.   The article 
describes revision of the RF amplifier "for s/n 1299 and under", and 
"1300 and over", (apparently the mechanical filter was changed at 
1300.)   Replacement of 6BE6 mixers with 6BA7's (only four steps, but 
one of them is enlarging the tube socket holes from 7 pin to 9 pin).  
Improvement of the IF selectivity curve and alignment and a change to 
improve AVC noise immunity

Unfortunately, the schematic is typical Sam's, that is, about two feet 
long, making it a pain to scan.  Some large libraries still have Sam's 
folders and even QST.  If you are unable to find either or both of these 
locally, I'd be glad to scan them for you.

73, Garey - K4OAH
Atlanta

GARY ELLIOT wrote:

>Greetings,
>Is there anyone on the list that could scan me the schematic of the early 75A2, the one that has the mixers as 6BE6's  NOT THE 6BA7's.
>I would greatly appreciate it so I can continue with my restoration and search for a earlier manual.  Thanks in advance.
>
>73 Gary
>  
>

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