[Collins] 75A3 accessory?

[David L. Thompson]

I thought the main difference between the 75A2 and the 75A3 was the A3 had a
product detector?  Collins would even modify your A2 for you to bring it up
to A3 specs.  The 75A4 product detector still left something to be desired
compared to say a Drake R4 series RX..may have to do with AVC/AGC.  I have a
Hammarlund Engineer modified HQ120 and he used the popular circuit of the
day which is the 12AU7
(its a 12AU7A).  He put it in so its switched in when you go to CW.   SSB
sigs have that pump you hear on the 75A4 or even the HQ170.
Collins seems to have fixed that with the S1/S3 RX!

Dave K4JRB

> Are you sure it's not a 12AU7? That was a very common product detector
> modification. Basically it amounted to building a 75A4 detector in the
> receiver.
>
> Regards,
> Darrell, WA5VGO
>