[R-390] New (to me) R-390A

Sat, 25 May 2002 09:15:48 -0700

Barry,

Here is another way to align the tube 'blind' that works with the type of
tube sockets in the R-390A.  There is a tit on the rim of the shield
attached to the socket.  You can feel it with your finger.  Use the same
finger to find space of the 'missing' pin on the bottom of the tube.  Align
these two points and the tube will plug into the socket.

This was taught to me by a Master Sargent on my first day in the field with
the USAF in the 60's.  Funny, in one year of tech school nobody mentioned
it.
Craig

-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of blw
Sent: Saturday, May 25, 2002 8:10 AM
To: [email protected]
Subject: Re: [R-390] New (to me) R-390A

My radio has been in a rack for a long time. I usually leave a few inches
for cooling space on the top with enough room to get my hand inside. I can
get all of the tubes out, including V207. The problem I had was orienting
the tube correctly when putting tubes back in since I couldn't see well. I
scanned the line drawing of the top and bottom layouts of the radio. I use
these sheets to write notes when I test all of the tubes, etc. The most
useful thing about using prints of the layouts is using notes on each tube
base how the tube should go in. I drew almost complete circles to indicate
the pins for each socket. I look at the sheet and orient the tube right
before trying to push it down into the tube base. It takes all of the
guesswork out of putting the tubes back in. Saves a lot on bent pins and
saying bad things that cause family members to come see what is wrong.

the other other Barry

> I've been able to get V207 out and in again without removing any
hardware --
> maybe nearby tubes.
>
> If you have an IERC heat dissipating shield, they're friction fit.  Just
> grab the top edge with a needle nose pliers and pull up -- maybe with a
bit
> of wiggle action.  The shiney bayonet ones are generally easer.  Just put
a
> small screwdriver into the one of the spring retainer slots and rotate --
> make sure you're going in the right direction.  It will pop up, then fish
it
> out with the needle nose or a bent paper clip.
>
> OH -- just remembered, before starting, work the tuning knobs to raise the
> slugrack for maximum clearance.
>
> After you've got the shield off and out of there, you can use one of those
> wire tube pullers, or I've found the tong type to be even better.  These
> look like kitchen tongs, but with "tooobuler" shaped ends coated with that
> tool handle rubber dip.  They were originally made for use as tube
pullers,
> then repackaged (by GC for example) as tongs for use in etching PC boards.
> (Just don't squeeze too hard ;-)  Another trick is to use some adhesive
> tape -- electrical, duct, scotch, whatever and work it onto the sides of
the
> tube, then pull up while gently wiggling.  The same method may be used to
> lower the tube into position, then press down on the top (with some kind
of
> cushion so the "nibbie" doesn't puncture your index finger.)
>
> If the tube or tube shield are stuck, well that's another story.
>
> Barry

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