It never hurts to ask Alpha for information instead of speculations...
The early 99 amps used a board at the front of the bandswitch (inside the
front subchassis) to turn on the plate choke relay that K9FD's amp has,
this relay pulls down the clapper arm to short out part of the plate choke
on higher bands. If the arm isn't adjusted to pull down solid enough, the
contact point can burn.
If anyone ripped off Ameritron it wasn't Alpha. Alpha changed to the RF
Parts RFC3 plate choke, bought in batches from RF Parts, then started
winding their own to the same specs. It will work in the earlier 99, no
other changes were made.
All the bandswitch wafers WERE aligned correctly when the amp was built,
how could it have passed a 48 hour transmitting burn-in? Who has been
poking inside of a 15 year old amp since it was originally adjusted?
Email Alpha for the 99 factory adjustment procedure.
http://www.alpharfsystems.com/
Glenn AE0Q
On Wed, Apr 26, 2017 at 9:06 AM, Jim Thomson <jim.thom@telus.net> wrote:
> Date: Tue, 25 Apr 2017 18:52:14 -1000
> From: Merv Schweigert <k9fd@flex.com>
> To: amps@contesting.com
> Subject: [Amps] Alpha 99
>
> Any Alpha 99 gurus out there, I have an early model 99 with the tapped
> plate choke and clapper system. The clapper has finally a hole burnt
> in it, and I was thinking I have seen a late model 99 with just a choke in
> place of
> all that relay / clapper junk. I usually use Ameritron chokes in my home
> brew amps and hoping one will fit the 99, has any one done this?
>
> Also does any one have updates and setup information on setting the various
> pots on the control board?
>
> Need to pull the amp out of service and replace the rear wafer on the band
> switch, it was not aligned when built and the rear wafer is 1/2 step
> off, thus burning a contact or two.
>
> Thanks 73 Merv K9FD/KH6
>
> ## I believe the alpha used a 2 section plate choke, and the bandswitch
> shorted out
> one section of the plate choke, when on the higher bands. Done, so both
> windings
> wont series resonate on the upper bands. The henry 8 k ultra did the same
> thing, but
> used a relay. Later alphas ripped off the gapped choke idea from
> ameritron, and
> came out with their own version. IF the newer alpha gapped choke fits,
> and is not
> too long vs the oem choke, its should work. The ameritron choke, IF it
> fits, should
> also work.
>
> Jim VE7RF
>
--
Glenn and NATCH Katie,
NADAC Elite Versatility Award, O-WV-E, O-TG-E, HP-O,
MXB, MJB, OF
http://www.hoopsandjumps.com/
http://funagility.webs.com/
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