[Collins] 75A2 / 75A3 mixer modification

[Dr. Gerald N. Johnson]

On Tue, 2006-06-27 at 12:41 -0400, Jim Brannigan wrote:
> I changed both mixers in a 75A3 many moons ago, 
> 
> QST 56,57,58?
> 
> Jim
> 

The ARRL on line index for QST from 1915 on doesn't admit such an
article. My index searches spotted a mixer article in 73 magazine for
October 1961. I recall more than one such article on triode mixers, but
I didn't find that issue in its box on the shelf so I couldn't check it
out. I didn't check CQ indices for the late 50s yet.
> 
> > On Mon, 2006-06-26 at 18:56 -0700, Glen Zook wrote:
> >> I had an inquiry about a 75A3 that has had the first
> >> mixer changed out from the 6BA7 to a 12AT7.  Since I
> >> had not seen this change before I thought that I would
> >> see if anyone had any information on the modification
> >> so that I could pass along the information.
> >> 
> >> Of course the same modification would work on the 75A2.
> >> 
> >> Glen, K9STH
> >> 
> > I think that was published in an early 73 magazine, though it could have
> > been a 50s vintage CQ that is in my collection. The 12AT7 has far lower
> > noise but also lower gain. It may take days to find the article, but I
> > recall it being published.
> > -- 
> > 73, Jerry, K0CQ, Technical Advisor to the CRA
> > All content copyright Dr. Gerald N. Johnson, electrical engineer
> 
-- 
73, Jerry, K0CQ, Technical Advisor to the CRA
All content copyright Dr. Gerald N. Johnson, electrical engineer