[Boatanchors] restored radio question

[J Forster]

jeremy-ca wrote:

> It appears that some old wives tales and other myths never die.
>
> New electrolytics, once reformed from a long rest, can be left alone for
> many years again. Some of my collection doesnt get turned on for 5 years or
> more after restoration and they suffer no ill effects. If an electrolytic is
> an ancient original it was already starting the breakdown process when the
> radio was stored, no amount of turning on will do anything except hasten its
> demise.

Not so. I've successfully reformed many old electrolytics and once reformed,
they work just fine. However, reforming requires several days, and running the
equipment occasionally, keeps them in good condition.

> Receiving type tubes, if not gassy when stored, wont be gassy in another 10
> years or more. Some also attribute the glow from some beam tubes as gas when
> in fact it is simply charged electron flow.  It is a different story with
> some transmitting tubes that have an established reputation of having seal
> problems.

By operating old, slightly gassy, tubes in a tube tester with both filament and
plate applied, it is possible to degas receiving tubes. (The plate voltage is
needed because it's necessary to ionize neutral gas molecules before they will
react with some getters.) I've done it with several hundred WW II tubes. About
90% are recovered using this technique. Occasional use will keep them happy.  As
to 'old wives' takes' I made careful engineering measurements on this topic
about 5 years ago. I wanted to restore some WS 19 sets to original condition and
had no desire to realign them, hence wanted to keep the original tubes in their
original location. Oh, and helium (present as a trace in the atmosphere)
diffuses through most glasses, so even a tube  with perfect seals can go soft.
It's easy to prove that by exciting a gassy tube and looking at the glow with a
spectrometer. Beam power tubes can have envelope glow where the accelerated
elewctrons hit the glass envelope.

Best,
-John

> Rubber insulation deterioates over time so be sure to check AC line cords at
> every use.
>
> Carl
> KM1H
>
> ----- Original Message -----
> From: "J Forster" <jfor at quik.com>
> To: "Gerry Steffens" <gsteffens at pitel.net>
> Cc: <Boatanchors at mailman.qth.net>
> Sent: Tuesday, October 09, 2007 11:23 PM
> Subject: Re: [Boatanchors] restored radio question
>
> > IMO, I'd run each a few hours (say 4) every month or two. Here's my
> > reasoning:
> >
> > Electrolytic capacitors need to be kept formed, and after reforming, a few
> > hours
> > a month should be enough to keep them in good shape.
> >
> > Tubes need to operate a bit to prevent gas buildup. For this to happen,
> > they
> > need to be operated with BOTH filament and plate voltages applied.  BUT,
> > I'd not
> > run then so long that they get 'used up'
> >
> > FWIW,
> > -John
> >
> >
> >
> > Gerry Steffens wrote:
> >
> >> OK Anchorites, what do you think about the following?
> >>
> >>
> >>
> >> I have approaching 300 radios in the collection.  Many work fine to
> >> adequate
> >> for now.  Many others have been fully restored.  Hopefully, more will be
> >> restored after retirement in a few years.
> >>
> >>
> >>
> >> How often and for how long per session should these functioning radios be
> >> turned on and used to preserve their functionality?
> >>
> >>
> >>
> >> Gerry