[R-390] OT: Low-voltage tubes

[Roy Morgan]

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!
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