[Milsurplus] Collins 75A-4 Receiver Coverage

[Mike Morrow]

Robert wrote:

>I thought someone else would have asked this err now but the obvious question 
>is why buy the limited coverage 75A variant instead of the 51J? 
>... God knows SAC could have gotten away with buying 51J-4's.

The answer is that the 75A-4 is designed purposefully for SSB reception and has
front panel controls specifically to accomodate SSB.  Apparently it was the
first "all-in-one-box" Collins receiver that was rated for CW, AM, and SSB.

The earlier 75A receivers, all the 51J receivers, and even the R-390(*) receivers
were AM and CW.  No *official* manufacturer's rating or controls for SSB.

I think that the closest contender for bona-fide SSB service would have been an R-390A
with an external SSB adapter like the TMC CV-591/URR.  But those came after the 75A-4.

Mike / KK5F