[R-390] New owner with (probably dumb) questions

[Jim Miller]

From:
http://r-390a.us/R-390A_Modifications.htm
"Tube shields:  Tube shields are needed on V201, V206, V505, and V701 (HSN
issue 5, page 3 or HSN reprints, page 3).  Others are often removed if
shiny, but should be kept in place if black (inside and outside).  IERC
shields are the most highly regarded, with WPM coming in second."


----- Original Message -----
From: "blw" <ba.williams@charter.net>
To: "R-390 List" <r-390@mailman.qth.net>
Sent: Sunday, April 20, 2003 10:27 PM
Subject: Re: [R-390] New owner with (probably dumb) questions


>
> > Almost all of the R-390's had silver tube shields on them. The IERC's
are a
> > rare item. You can get a set of them but it will significantly increase
your
> > investment in the radio. I am not convinced that they are worth the
money
> > they are selling for these days. Tubes are still pretty cheap ...
> >
> > Enjoy!
> >
> > Bob Camp
> > KB8TQ
>
>
>
> I think that if you are going to spend the money on the black IERC
shields,
> then get the best shields. I used to have a detailed report of lab tests
> that somebody sent the list a few years ago, probably Dr. Jerry. Anyway,
> without finding the specs of the tests, the shiny shields do damage to
tube
> life by reflecting heat back to the tubes. There are 2 types of IERC tube
> shields. The type that doesn't do the job as well are the type with only 3
> or 4 large finger tabs on the inside to contact the tube glass. The good
> shields are the ones with a lot of small, mini fingers to grab the glass.
> Those dissipate the heat more efficiently.  That report had temps from the
> different combinations, etc.
>
> There are only a few tubes that should be shielded. Chuck has those listed
> on his website, or he used to have it up there the last time I looked.
> http://www.R390A.com/. I only shield those that he suggests.
>
>
> Barry
>
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