[R-390] The ultimate heresy?

[Tim Shoppa]

mike Kana <aa9il at sbcglobal.net> wrote:

> Hi all
>
> Dangerous question....  Has anyone attempted to
> completely
> rebuild the modules or (entire?) R390 A radio with new
> low noise
> resistors, modern caps, wiring, etc - obviously all
> the mechanics, tubes, slugs, major components, etc
> stay.  
>
> Regards
> Mike 
> AA9IL
>
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Well, many of us have gone through and replaced any questionable caps
and any questionable resistors in some/all modules.

Doing everything everywhere could prove disastrous in the case of
special tempco parts. There must be some of these in the PTO.

And remember there's not just the caps in the chassis but also caps
inside many of the coil cans.

Replacing wiring sounds a more than just a little bit overboard.  You'd
still have the same old connectors (which would be the weak point).  Some
here have replaced individual bad cables etc. in the harness, and it's
a fair amount of work to unlace the harness, remove the cable, put in the
new cable, and lace it all back up.  While I've done some cable-lacing
in the past I can guarantee you that I would never be able to put it all
back together as well as it was done at the factory.

The parts most likely to be in need of refurbishment are the mechanical
controls and switch sections.  Many of these have custom wafers/contact
arrangements that make them certainly NOT off-the-shelf items. Usually
donor rigs are found and/or Deoxit + some very particular refurbishment
takes care of the problem area.  I'm guessing the cost of fabricating
new switch wafers/contacts throughout would run into thousands of
dollars, very much discouraging en masse replacement from "new stock".

Tim.