Hello to All on the reflector
I usually don't get into discussions on the reflector but enjoy reading them.
I have some questions about the Alpha 99 amplifier . I bought about 8 month
ago . I have lost the tuning capacitors in this amplifier twice . Alpha has
sent me the same capacitors for replacement. I am waiting for the third set now
. I have been talking with Gordon Hardman, via- E-mail . Hoping to come up with
the reason these capacitors keep blowing out . These capacitors have a rating
of 5 x 75 pf at 6 kc . I think if they were increased to 7 kv , it would solve
the problem.... ::
If there are other users here on the reflector using the Alpha 99 on 160 please
let me know if you have had this problem . The amplifier works beautifully on
all the other bands with out a problem . Gordon tells me they have not had any
reports of this problem from other owners . Perhaps most operators do not use
their amplifier on 160 . Which separate the men from the boys. As the saying
goes ...
Here what Gordon had to say .
Randy,
I think we are talking past each other. I was referring to the INPUT SIDE of the
pi-L network- this network is connected between the plates of the tubes and the
coaxial output. The pi-L network is used to transform the impedance of your
antenna to the impedance the tubes need to see in order to generate 1500 watts
with around 2.5kV on the plates. This is around 2100 Ohms give or take, and the
pi-L network's job is to produce this impedance regardless of the antenna SWR.
So the RF voltage swing on the plates of the tubes is always the same, and hence
the stress on those capacitors is always the same.
Soliciting your input .
73 Randy
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