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An 8877 is NOT a thoriated tungsten fil !? ? ? ?On the 8877, and other OXIDE tubes, you CAN'T? run the heater at reduced voltage and increase tube life.? ?You can only do that on? directly

In the book by Eimac called “The Care and Feeding of Power Grid Tubes”, in para 6.11.1 Maximum Tube Ratings; it states that: “At some point in filament voltage [reduction] there will be a

Great follow up Dave. Thanks and 73, Alek VK6APK.

You should have been a poet, Hal. Totally agree !

I just calculated the percentages of Mains and Filament Voltage drop from idle power to 1.3 KW. The Mains dropped 2.4 Volts from 242 VAC, that is a 1% drop. The Filament Voltage dropped 0.29 VAC, that

On Mon, Oct 16, 2023 at 01:53 PM, Dave w6de wrote: > > > > Measured Voltage results of Alpha 9500 key down testing. > > > > AC Mains Voltage at Amplifier switch box. > > > > 142 VAC Amp on

I just remembered the company, it was Sola and the product is/was the Constant Voltage Transformer. Looked on ebay and there's quite a few listed with a wide range of

Years ago there was a company that produced a regulating 1:1 or 2:1 transformer with a ferro-resonant winding. hTeret had a capacitor across to hold the voltage steady. I don't know the specifics of

Gents, One of the bug-a-boos about QRO tubism is the regulation and acceptability of filament voltages. Okay, tube manufacturers tell us "10%," and we have to live with whatever Con Edison or

Measured Voltage results of Alpha 9500 key down testing. AC Mains Voltage at Amplifier switch box. 142 VAC Amp on at Standby. 239.6 VAC Amp at 1.3 KW into Dummy load Filament Voltage 5.3 VAC at

Hey Dave, If your amp has been operating "normally" for a length of time (i.e., with apparently normal/full output) and only recently started showing signs of decreased power, then it's probably a

And a "soft" tube acts as a soft fuse. W4DNR

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,

The duds could be eye candy for one's shack.? Maybe put them on QRZ, etc. Andy? K9ATX

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.

Yes, when shop/shack was constructed, I specified the wiring as #10 and multiple 240 outlets each on separate breakers (according to code) and over saw the construction and wiring. I know if it was

Hi Dave. My question is about your AC mains supply. Is it up to the task? Section 3.2 and table 3-1 talk about what you can expect from different mains supplies. Also, I looked in the manual to see

I’ll do that this afternoon. 73, Dave, w6de Sent: 15 October, 2023 02:04 To: [email protected] Subject: Re: [ham-amplifiers] Symptom(s) for a fading 8877 tube? No need to "side-line" your

I may just do that after I test my spare tube. 73, Dave, w6de

Plan B: The few extra hundred watts really doesn't make much difference. Just use that tube until it doesn't......