[R-390] Waking up my non-A

[Roy Morgan]

At 07:09 PM 1/6/2006, David C. Hallam wrote:
>In spite of all that has been written in various reflectors, etc. and
>conventional wisdom aside, it is not a good idea to "bring up slowly with a
>variac" a vacuum tube radio.


Hear, hear!  I agree.
My diatribe against using variacs this way is available upon request.

It turns out that the main filter cap in an R-390/URR is an oil-paper cap 
and is very unlikely to be shorted or leaky. In any case, it won't exhibit 
the leakage phenomenon that gets you in trouble by "bringing it up slowly 
on a variac".  Still, I urge you to not do that to an R-390 of any sort.

There may be other caps in the R-390/URR that will cause trouble.

Morgan's Diatribes available:

Variacs.txt  Why your variac can blow up your radio and what to do about that.

powercordsandbypassing.txt  About fused line cords and how they can make a 
widow of your wife.  How to bypass your line cord for RF and reduce the 
chances of disaster, AND solve the "hot chassis" phenomenon.  Information 
about the European line cord color code, and about fuses, GFI devices, and 
outlet testers.

reform.txt How to reform electrolyitc caps and how to test other caps for 
leakage (like the Black Beauties)


Roy



- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Cell 301-928-7794
Work: Voice: 301-975-3254,  Fax: 301-948-6213
roy.morgan at nist.gov --