Vacuum Tube Equipment

Roger Kolakowski
Sat Sep 3 07:38:45 EDT 2005

If the radio was working before, but had hum, and is now dead silent, I
would check the B+ voltage before and after the hum-bucker coil on the
speaker. If no coil then before and after choke between the filter capacitor

You might have fried the rectifier tube, if you have filament voltage and no
smoke (from the transformer) and absolutely no audio, even slight hum turned
all the way up, then the two stages to start with are the B+ supply and the
audio output, which are "intertwined" on many of the "older" tube sets.

The voltage you are looking for is around +350 vdc. which will give you a
kick on dry land and probably stop your heart if you are standing in water.
Additionally, if you have an open circuit before any load on the supply, the
filter caps will retain the high voltage even if the radio is turned off.
Some care should be observed.

----- Original Message ----- 
From: "A. Joseph Ross" <>
To: <>
Sent: Friday, September 02, 2005 9:39 PM
Subject: Vacuum Tube Equipment

> Well, I got the parts to replace the filter capacitor in the old vacuum
tube radio that I have.
> I've done this a number of times before, but for some reason, after I
installed the new
> capacitors and turned on the radio, I couldn't hear anything.  The tubes
light, as do the dial
> lamps, but no sound at all.  I checked the wires to the speaker, and they
seem fine.
> So it seems that I must have damaged something in and around the filter
capacitor.  Any
> suggestions on how I can find out what?
> -- 
> A. Joseph Ross, J.D.                           617.367.0468
>  15 Court Square, Suite 210                 Fax 617.742.7581
> Boston, MA 02108-2503              

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