[Collins] 75A-3

[Joe Walden]

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.......