I almost hate to break the thread chain on the Bird Meters. Every day I seem
to learn something new. However, I have a couple of questions for the group
regarding an Amp Supply LA-1000 that I picked up.
Upon opening the unit, it had obviously just barely survived an episode with
a secret cult made up of members of the meat packers union.... Well, wait a
minute, this was in such bad shape I might be insulting the meat packers if I
said that......OK I'll take that back.
The main circuit board had arc burns on the bottom from what appears to be an
insect nest that went undiscovered when the last lid powered the thing up.
The power input jumpers to choose between 110 and 220 were wired incorrectly,
all tubes were bad, the filter caps in the voltage doubler were unsoldered, and
the list continues. What the heck, I always enjoy a good challenge!
My questions to the group are:
1. On the tuned input board, the toroids for 40 and 20 meter inputs obviously
got hot. They rest directly on a small circuit board and the board is
discolored. The windings themselves look to be OK. I am guessing this thing was
driven near max input for long periods and that's what heated these things up.
Anyone have any guesses if the toriods may have changed their values
significantly
due to the heat?
2. Since I need to replace all 4 6MJ6 sweep tubes, do I find a nice set to
use this weekend at Timonium or might I look at a conversion with some other
tube?
3. For some reason, it appears a previous owner clipped out a bus on the
loading capacitor so it now is just using two of its three gangs. It also
appears
there was playing with the bandswitch. (Bandswitch appears OK). My sense is to
return both to the original configurations in the manual. Anyone know of any
reason someone might have tried this? Maybe a CB'er trying to juice up 10
meter performance, but who knows. By the way, the coils and plate choke appear
OK.
As a side note, I too am intrigued with some of the new high voltage
transistors. I have always wanted to construct a near legal limit solid state
amp.
Since some of these are in voltage ranges near 110/220, if makes me think there
ought to be a way to develop a supply without a transformer or switching
circuits to really lower the cost of the project.
Thanks in advance for everyone's help on this.
John Coupe
WA3BXH
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