[R-390] Corcom 3ED1 filter

[Perry Sandeen]

Good news my fellow Heretics!
The Corcom filter screw mounting holes are an an exact match for the OEM filter.
Now it's true (close your eyes purists) that you will have to cut the OEM round hole to a rectangle to inset the filter. but the filter covers the top and bottom of the hole so it's hardly noticeable. 
Now you have the chance to repair on OEM wiring configuration that does not meet current (pun intended) standards.
The "Hot" wire should be attached to the on-off switch.through the fuse.  AFAIK both the "A" and our sister receiver, the SP 600 originally had the fuse on one side of the input and the switch on the other.
There are several benefits to do this upgrade.  First if you lose your dedicated green ground, you won't get nasty tingle, or worse, if you'd touched the chassis and a true ground.  Next the filter allows you to use a standard computer cable instead of the usually found funky power cord connections.
One gains space to be able to replace that bathtub electrolytic used on the RF gain control.  It most likely has high leakage being around 50 years old.  Additionally there is now space to install a CL 90 thermistor for a slow warm-up and will have open space so it does't cook anything when it heats up.
Now if it does't bother your conscience, you can sell it on ebay for more than you paid for the Corcom, (Not recommended) 
Regards,
Perrier