[R-390] RF Deck Problem

[Bob Camp]

Hi,

The following applies to a R-390A and may not work with a R-390 not an A. I
don't have a not an A handy to check it on. However I'd be glad to give a
warm and loving home to any strays out there :)

There is a way to hook up the RF deck, but it's a *major* pain. The IF deck,
the audio deck, the PTO,  and even the power supply all do just fine that
way but not the RF. You have to more or less flip it up over the back of the
radio. Imagine the radio sitting normally with and the RF deck sort of
sitting straight up in the air. The issue is that both the radio and the
deck are pretty big and need to be supported properly so you don't destroy
the harness. It is a classic need at least four hands and a bunch of 2x4's
sort of job to get it all positioned properly.

The easiest way to do the same thing would be to get a wiring harness from a
defunct radio and hook it up that way. The second easiest way probably is
clip leads.

You may have already tried the following - if so I apologize for bringing it
up ....

Normally here's how it is done:

    1) Figure as best you can if the problem is at all frequency dependant.
Even if it's not that narrows things down.
    2) Grab your supply of tube socket extenders or make a set if you don't
already have any. They also show up on the auction sites fairly regularly.
    3) Get a copy of almost any of the R-390 or R-390A repair TM's from the
usual download sites.
    4) Check the DC voltages on the module.
    5) Check the AC voltages on the module.

At that point you should be able to ask - "what's wrong in the first mixer
stage?". Needless to say that's a *lot* easier than going after the whole
assembly. Just about everything you can get at under the module is available
on one tube socket pin or another. The key to the process is the extenders.
The only thing to be careful about is plugging them in to a live radio.
Something about B+ on the clip on pins and your hand completing the circuit
...... (yes that is the voice of experience speaking).

    Take Care!

        Bob Camp
        KB8TQ




----- Original Message -----
From: "Kurt Schnabel" <classicmotorcycleclub@hotmail.com>
To: <r-390@mailman.qth.net>
Sent: Thursday, January 02, 2003 8:27 AM
Subject: [R-390] Happy New Year!


> Happy New Year to all members!
>
> Would like to begin 2003 asking the R390 experts: Can I repair the R390 RF
> module with all cables connected? All Tubes were checked, but I could not
> find any faulty component with the supply disconnected. Can I tune to a
> specified frequency, say 10 MHz and try to find the reason for a very weak
> reception?
> Many thanks for your help!
> Kurt Schnabel
>
>
>
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