Re: High filament current on the 8877 amplifier tube
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I bought one off of Ebay once for about $30. The seller claimed it had low output. It didn¡¯t matter to me because at the time I was contemplating building an amp with one of them. My elmer Eric, WB4VVI(SK) always insisted on using a tube with low or no output to test the HV section and grid drive section. That way if you missed something during your construction and an ¡®event¡¯ happens during the testing phase, you will have ruined a tube of little value as opposed to a new or one with full output. ? Mod-U-Lator, Mike(y)/W3SLK ? ? ?
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From: [email protected] [mailto:[email protected]] On Behalf Of DupyRail
Sent: Monday, October 16, 2023 10:22 AM
To: [email protected]
Subject: Re: [ham-amplifiers] High filament current on the 8877 amplifier tube? The duds could be eye candy for one's shack.? Maybe put them on QRZ, etc.
Andy? K9ATX
On 10/16/2023 1:46 AM, Tim Duffy K3LR wrote: I am still testing 8877s here. Two or three every day. They warm up with filament only for 4 hours before HV. What I have learned is that 8877¡¯s drawing 15 amps of filament current are bad tubes. They draw zero plate current. So the five tubes that are high filament current ones, are ¡°duds¡± ? So what is the proper way to dispose of these bad tubes? ? 73 Tim K3LR ? ? Most 8877 tubes that I test draw 11 amps of filament current at 5 volts. I have tested three recently that draw 15 amps of filament current. All of these tubes are used and have little ¡°dings¡±. ? Is 15 amps an indication of a problem tube? Or should I apply HV to the plate and see what happens? ? 73 Tim K3LR
-- "Where the Old Soo crossed the New Soo" Duplainville, Wisconsin ? Web page:? ? Youtube Channel:?
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