FWIW, a member of our contest club had problems with massive IMD
interference to other radios caused by bad PIN diodes in a used Alpha 86 he
bought. Being a thrifty fellow, and not needing QSK for multi-multi
contesting, he simply bypassed the PIN diodes with a standard relay-based
T/R switching system (not even a vacuum relay.) Aside from the PIN diode
problem, my understanding is that the RF portion of the amp is excellent and
a real workhorse.
73, Dick WC1M
> -----Original Message-----
> From: SamuelR717@aol.com [mailto:SamuelR717@aol.com]
> Sent: Sunday, June 05, 2005 11:59 PM
> To: amps@contesting.com; n4dek@triad.rr.com
> Subject: [Amps] Alpha 86
>
>
> 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
> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>
> 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
>
>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|