[R-390] Ballastubes

[Barry Hauser]

A caution on the paperclip thing ...

I have recently found that some chrome paper clips are not exactly
conductive out of the box.  Apparently they're covered with some other kind
of silvery finish or chromed then clear coated. I'm in the habit of using
jumbo paper clips to make temporary test connections as they are of a
convenient diameter.  Came across this recently.  Thought the radio was
dead -- nope -- defective paper clip.  Check first with an ohmmeter.  I
found some could be scraped and then made the connections.  Just don't
assume zero ohms -- or infinity either.

Barry

----- Original Message ----- 
From: "Drew Papanek" <drewmaster813 at hotmail.com>
To: <r-390 at mailman.qth.net>
Sent: Thursday, July 01, 2004 1:04 PM
Subject: [R-390] Ballastubes


>
> Walter Schulz  <k3oqf at localnet.com> wrote:
>
> >Does anybody know where I can find Ballast tubes for my R-390A/URR? Sure
> >would appreciate any >advice on this.
>
> Walter,
>
> You've by now seen the high price quotations for the 3TF7 ballastube,
making
> modifications to
> replace that tube attractive.
>
> I suggest you go to r-390a.net.  Click on references, Pearls of Wisdom.
> There you will find  a wealth of information (and controversy!) regarding
> that R-390x topic and others, all gleaned from this forum over the years.
> Thanks go to Wei-i Li for his untiring compilation efforts!
>
> I personally like and use the "Two 12BA6 and a paperclip" mod whereby the
> 6BA6's used in PTO and BFO are replaced with 12BA6's and then the
ballastube
> socket is jumpered out (a piece of paperclip
> works well).  The mod is extremely simple, inherently reversible, and
> dissipates less heat  than the
> various modifications or even the stock configuration.
>
> One mod mentioned is Dr. Jerry's simple AC current regulator.  I can
e-mail
> you the schematic and notes.
>
> Drew
>
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