|[AMRadio] Amp / Tube question|
jpl15 at panix.com
Wed Nov 23 01:34:15 EST 2005
Now, be it known to all hams by these presentiments: That I have never
owned or operated a 'real' RF amplifier before - I've always run at
whatever power the transmitter in use was rated for. So forgive me for
asking questions that might be 'obvious'.
I got around to wiring in the 220 circuit for my 'new' Ameritron AL-80
[note it's a plain -80, not an 'A' or 'B'] to see how much smoke I could
I took out the tube (3-500Z) and brought it up slow on a variac and 100W
lamp-load - got it up to full line voltage with 2600V registering on the
meter. Checked the tube for gross shorts and fil continuity - good to go.
Put the tube in, plate cap off - fils light, fan runs - I left it to soak
for an hour or so.
Shut it off, put on the plate cap, hit the power sw - BAM! as Emeril
might say. A large blue flash went off in the tube and I welded the line
fuse to it's cap. And smoked the meter dropping resistor - though it's
been replaced before, I see.
So obviously the jug is toast - or is it? Am I missing something really
stupid here? I thought to ask right before I buy a nice new one and cream
Finally, I have no manual for this unit, and BAMA only lists the "A"
version, which of course is substantially different. I have found one
book for sale at a 'manuals' website, but if anyone has one that they'd
like to loan me for copying - I'll make a PDF of it and send you back the
original plus CDR, and pay for the shippin'.
Cheers, and Happy Thanksgiving....
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