N4DEK wrote
I have just purchased an Alpha 86 amplifier that is supposed to be in like
new condition inside and out and working perfect with full output. This is my
first Alpha amp and I am interested in any pros/cons that I need to be aware
of with this model. I'm curious about all the talk about the PIN diodes being
weak in this one. What if anything do I need to do to protect these from
being a problem? Do I need to keep some spare fuses on hand for this? Any and
all help welcome.
Thanks,Don
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Base on my experience, get a large supply of the small receive fuses! I had
an 86 for several months; it was a fine amp, EXCEPT for the pin diodes
causing the receive fuse to blow every 4 or 5 times I used the amp (into a quad
with flat SWR on all bands). When the fuse blows, the amp still functions,
but
you can't hear anything unless you manually switch into "Standby" mode. Not
fun trying to break a pile-up that way! I must admit that I hoped the guy
who sold it to me (without mentioning this problem) would develop some kind of
very unpleasant skin condition...
I had LENGTHY conversations with Alpha Tech Support. I replaced the pin
diodes, at their suggestion, which had no effect (which they warned me might
happen). Their final word was that not much could be done--some 86s had this
problem, some didn't, and they really didn't know why or how to fix it, short
of pulling the pin diode system and replacing them with vacuum relays. They
also warned me NOT to use a higher rated receive fuse, at risk of blowing the
HV PS.
I finally sold it (at a loss) to a W6 who is a broadcast engineer, and who
rebuilt it with hi speed relays and re-sold it.
I eventually brought a used 87A. I had some initial probs, but worked thru
them with help from Tech Support, and it has served me well for the past 2
years. I still like Alpha products, but they seems to have gone astray on the
86.
Good luck, and 73
Sam
AA3VD
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