[Elecraft] K3 and Alpha 91b

[Brian Machesney]

Mike,

I have used my K3 and A91b successfully on all bands from 160 through 10
meters for over a year. No problems with SSB on any bands. I have run full
output on 160 and 80/75, both SSB and CW. Net: I can't think why you're
having trouble.

I do have one problem on the low bands that I do not associate with the K3
but might be playing into your situation somehow. I believe my house wiring
is picking up RF, which kills my DSL connection whenever I run high power on
160 and sometimes when I only run 100W barefoot from the K3.

Have you run the setup into a dummy load?

Brian K1LI

On Tue, Jan 19, 2010 at 3:59 PM, <n9qr at aol.com> wrote:

> I have an Alpha 91b hooked to the K3 (SN 8376) and I'm having an "Odd"
> problem ... on 75/80 meter SSB, if I run the amp at 45 watts, which is what
> works on CW without issue, I encounter significant nuisance tripping of the
> Amplifier to the fault condition.  The amp also exhibits a power spike into
> the 2KW range often times when it faults.  If I reduce the  power to 30
> watts on the K3, the amp runs 1500 watts OK without tripping.   Please ....
> resist the temptation to say "Run at 30 watts then".  All  other bands ...
> except 6 meters which I didn't check, do not exhibit this  issue.  Power
> out from
> the K3 is 45 watts and the amp runs  1500 watts  out with NO nuisance
> tripping.  I've talked to the tech's at Alpha and at  least one other K3
> owner
> has had this same problem.  He asked me to check  the amp with another
> radio
> so, using my spare radio, Yaesu FT-450, to drive  the amp I have no
> nuisance
> tripping on any band while running 45-50 watts into  the amp.  Neither
> radio
> has ALC hooked up, only the TR relay.  Both  radios and amp are grounded to
> the same ground buss.  RF calibration was  done when the radio was
> assembled and I have not re-done that process.
>
> Any ideas as to why the radio would exhibit a tendency to over drive the
> amp just on 75/80 meters?
>
> Mike N9QR
>