[R-390] RE: Field Changes

[David Wise]

>From: Laird Tom N [mailto:LairdThomasN at JohnDeere.com]
>
> 7           EIMB   shipboard installations  Decals located on VFO in
>supplementary radio
>                       see EIB-911           assembly and RF amp-spaces
>only lifier chassis
"Modified
>by FC7"
>
>of the connector. Then cables to J105 and J106 are swapped. I have no
idea
>what FC7 does! Roger N1RJ

The above text is a bit scrambled.  An original FC7 job will have
"Decals
located on VF0 assembly and RF amplifier chassis" that say "Modified by
FC7".  The mod was intended for radios used in "supplementary radio
spaces only".

It increases the value of two screen dropping resistors.  This
weakens the output of the VFO and the first crystal oscillator,
to reduce emissions that could be picked up by neighboring
equipment.  With less injection at the mixers, an FC7 radio is less
sensitive than normal, which is why they only applied it to the
less important radios where it didn't matter.  I learned this by
applying it to my own radio.  After I understood, I undid it, and
would never recommend that anyone else do it.  If I acquired a radio
with FC7 and it was for use and not a museum, I'd undo it.

73,
Dave Wise (SWL in Portland OR)