[R-390] Differences between CV-591 and CV-1758

[Don Reaves W5OR]

Randy, 

There are some circuit differences.  I'd say the CV-1758 is the improved
version internally.  The CV-591 and CV-591A are based on the TMC MSR-1 and
MSR-4, respectively, and the CV-1758 is based on the TMC MSR-9.  Those
models span a life time of mid 50's to mid 60's.  

Functionally, they are the same, and the interconnect diagrams are the same
to your R-390 or other 455KC IF receiver. The CV-1758 has an additional
front panel switch for a limiter on/off and a slightly different scheme to
select upper/lower sideband.

 
Don Reaves       W5OR
www.militaryradio.com