[Collins] 75A-3

[Dr. Gerald N. Johnson]

I think you should make those Collins bulletin mods. They can make some 
difference in the operation.

73, Jerry, K0CQ, Technical Adviser to the Collins Radio Association.

On 1/15/2012 10:34 PM, Joe Walden wrote:
> Hello again from Joe w5jdy in Okla...   Thanks to the members for good
> advice concerning the problems I had with the PTO unit and the low and high
> tunable IF's in the 75A-3 that I have been working on...  I got it from a
> friend and it did not work..  I removed some mods that were different than
> the manual and schematic showed and wired it according to the schematic...
> I now have it working on all bands with good sensitivity,selectivity and
> plenty of volume..  The PTO still won't zero on either end but is within the
> range of the error indicator..  (I adjusted it for zero in the middle of the
> band as I was told to do here on this reflector)..  My question today is
> about some mods that Collins sent out back in the 1950S...  I have these
> three bulletins...  Bulletin #1 is a mod to reduce internal noise and
> improve the signal to noise ratio under average operation conditions..
> Bulletin #2 is for receivers serial #1300 and over.    Bulletin #3 is for
> receivers serial #1299 and below..  My receiver is serial #391..  This
> bulletin concerns a 2 to 1 improvement in the cross modulation and blocking
> characteristics...  Should I make these modifications in bulletins #1 and
> bulletin #3???   Joe
> Thanks for your patience.......
>
> _