[R-390] OT: Low-voltage tubes

Scott, Barry (Clyde B) [email protected]
Fri, 15 Aug 2003 15:13:24 -0500


Roy,

Thanks for the advice.  I probably would have done just what you outlined
and blown the entire chain.  I haven't examined the schematic closely enough
yet to find the little Gotcha's.

Hmmm, if the 1L6 is working, perhaps I didn't do too badly with this
purchase.  I'm eager to get home and test it now.  I need to find out if I
have other blown tubes that I need to look for tomorrow as well.

Thanks!

Barry(III) - N4BUQ

-----Original Message-----
From: Roy Morgan [mailto:[email protected]]
Sent: Friday, August 15, 2003 3:08 PM
To: Scott, Barry (Clyde B); R390 (E-mail)
Subject: Re: [R-390] OT: Low-voltage tubes


At 11:20 AM 8/15/03 -0500, you wrote:
>I recently had to have a Zenith TransOceanic.  This is the H500 model so it
>is still tube stuff (except for the selenium rectifier).
>
>My question is do these low-voltage tubes glow very much?  These are types
>1U4, 1U5, 1L6, and 3V4.

Barry,

Beware:

1) The 1L6 is worth forty bucks if it is working.

2) IF you have an open filament in one tube, AND you run the radio on the 
power line, AND you then plug in a good tube, ALL The tube filaments will 
BLOW OUT.   This is because the filament filter cap has charged up to a 
high voltage and will apply excessive voltage to the whole string when you 
plug in the last non-open tube.

>  I put them in my tester and did not notice any glow
>but without the glow, some still tested okay.

The total filament power is extremely low.  Do your testing in the dark and 
use a magnifying glass to see the glow.

Roy


- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing!
7130 Panorama Drive, Derwood MD 20855
Home: 301-330-8828 Work: Voice: 301-975-3254,  Fax: 301-948-6213
[email protected] --