[R-390] Hosing those 390A

[Francesco Ledda]

compressed air... not water

-----Original Message-----
From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net]On Behalf Of Francesco Ledda
Sent: Tuesday, March 21, 2006 10:28 AM
To: r-390 at mailman.qth.net
Subject: RE: [R-390] Hosing those 390A


I have rebuild few 390a and other radios.  Some were so dirty that water
washing was required.

In the case of a 390A, I remove all the modules and put them aside.  I wash
the chassis with a mixture of water and Simple Green; I remove the excess
water with compressed water and leave it in the sun (Texas sun) for few
hours.

Next, I remove and label all the tubes from the modules.

Now, I wash the audio amp and the power supply modules; again, I use
compressed air to remove the excess water, and I put the module in a oven at
130 degrees for 30 min or so.

I remove slugs and coils,  from the RF group.  I degrease and wash the RF
group and dry it using the same methods mentioned above.  I clean the RF
coils separately with a humid cloth. I clean the variable capacitors, as
well.

Now, before cleaning the IF module, I remove the BFO and the mech filters
cover. Clean the top module with a humid cloth and a brush, and I wash the
bottom part hot distilled water; I hold the module, on top the sink, and I
spray water from the bottom, to minimize the possibility of water getting
inside the coils. Dry everything and start putting things back together.

I have used the same methods for many other receivers and never had any
problems.  My best and favorite 390A is a blue stripper that I bought for
about $100.  It was a great satisfaction to bring it back to life. I
repainted the front panel, knobs and redone the engraving.

By the way, I only replace failed components and black beauties.

I would never wash meters or PTOs.

Regards,

Francesco

-----Original Message-----
From: r-390-bounces at mailman.qth.net
[mailto:r-390-bounces at mailman.qth.net]On Behalf Of James A. (Andy)
Moorer
Sent: Tuesday, March 21, 2006 9:41 AM
To: r-390 at mailman.qth.net
Subject: Re: [R-390] Hosing those 390A


They are made of cardboard, but they are also impregnated with
something-or-other. Water bounces off them as off a duck's back. The slugs
themselves, however, are porous. The water doesn't hurt them, but they need
to be dried out. Better to remove them first. The meters started out
perfectly sealed, but they often aren't.

James A. (Andy) Moorer
www.jamminpower.com

----- Original Message -----

>
> Are not the coil forms of the R-390* made of cardboard? I have replaced an
> antenna coil due to the cardboard being scorched from excessive RF or a
> lightning strike. The slug wouldn't pass. Would not water dissolve the
> coil form? I would think that one would have to go to extreme measures to
> protect the coils from miosture during a water bath.
>  ..Steve...N8YE
>

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