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Author Topic: FL-2100B problems  (Read 1830 times)
ON5JW
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Posts: 1




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« on: June 12, 2004, 11:04:09 AM »

Hi,

I recently bought a FL-2100B but it seems to output only 250 Watt with 100 W input. I guess the tubes may need replacement? Is there a way to test the tubes? Or other hints or tips to check the amp out?

Kind regards,
Jan

ON5JW
VK2IZZ
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WB2WIK
Member

Posts: 21836




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« Reply #1 on: June 14, 2004, 11:56:49 AM »

If you feel comfortable working around high voltage and tube amplifiers, there's lots of things you can do to test the amp:

-Operate with just one tube (either one) and see what happens; then, operate with just the "other" tube (still one, but the other one), and see what happens.  If you get the same gain and output with just one tube as you do with two, chances are you've got one bad tube!

-Of course, look to make sure both tube filaments are "lighted" and glowing as they should be.

-While you're inside, look to be sure both plate "caps" (anode connections) are tight and secure, make sure both tubes are firmly seated in their sockets (they operate horizontally in the Yaesu, and that can make them get "loose" in their sockets much faster than operating them vertically with the bases down), and make sure there are no signs of any components being burned, cracked, or missing in the 572B plate compartment area.

The amp *should* draw about 500mA key-down under normal conditions.  Is it doing that?  Then, with just one tube, plate current should be about half that (about 250mA).

Remember if you operate with the amplifier's cover removed, two things are necessary:

1.  Defeat the safety interlock, or the amplifier won't turn on;

2.  Be careful!  2400 volts hurts a lot, or maybe worse...

WB2WIK/6
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