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Re: [Amps] OMPower 2000+ Heater voltage ? is 8.6 to 8.7 volt heater enuf

To: "'amps'" <>, "Edward stallman" <>
Subject: Re: [Amps] OMPower 2000+ Heater voltage ? is 8.6 to 8.7 volt heater enuf?
From: "Carl" <>
Date: Sun, 22 Sep 2019 20:38:37 -0400
List-post: <>
A couple of thoughts

What is the gettering/regettering process of that particular series of tubes? An arc is often caused by internal gases released when the tube is overheated.

Are you using a True RMS meter to read the filament voltage at the socket? If it is consistently low consider adding an external transformer and small variac, 10V transformers are common. I have never liked combining filament and HV transformers in one unit.

OTOH the manual claims that the boundaries are +/- 2.0V so why the obsessions from many about that voltage? If there is a valid reason for precision then by all means do it.


----- Original Message ----- From: "Edward stallman" <>
To: "'amps'" <>
Sent: Saturday, September 21, 2019 10:40 PM
Subject: [Amps] OMPower 2000+ Heater voltage ? is 8.6 to 8.7 volt heater enuf?

I was reading with entrust about the FU728 tube failure and heater voltage . I understand the heater voltage should be 9 volts , Checking my heater voltage on my new OMPower 2000+ It's reading 8.7 volts most of the time , sometimes flickering to 8.8 volts .... I've seen it as low as 8.5 volts on occasion's . At 1500 watts much less ..This has been a concern sense buying the amp close to two months ago . I've had one tube arc last week that blew a small fuse near the tube while using it on SSB . The amp was tuned properly and I was not tuning when the fuse blew .

Am I safe with the heater voltage at these levels ?

When the fuse went , I was thinking of moving the tap from 240V to 230V but it was already on the 230V tap ... Thought about moving it to 220 but left it where it was at . My line voltage reads 240 to 245.

Thanks for reading , like to hear your thoughts . Ed N5DG

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