Thanks, Phil. I've seen that specification from Ameritron and it prompted
me to ask the loss question since it's not disclosed by Ameritron. When I
see optional cooling fans being offered by manufacturers for RF switching
equipment and external tuners, I'm not left with a warm & fuzzy feeling
about their operating efficiency.
One area I need to validate is whether or not I had kept the SPE amp in
bypass during my 100W loss testing. I did not test the QSK-5 at 1KW;
testing only occurred at 100W with the SPE in bypass. My QSK-5 is modified
to work a bit differently than most units since I always keep the SPE key
line active and optically control MOSFET bias from the QSK-5.
http://72.52.250.47/images/QSK-5-Interface.pdf
But that part of the circuit is strictly at the logic level and in no way
interferes with MOSFET bias voltage settings. I took this measure since I
never have to worry about truncating the first keyed element in a series of
characters. That's a limitation of the QSK-5 and Array Solutions
QSK-Master unless the amp remains keyed. But in amps where FET or plate
idling current is non-zero when the amp is keyed without drive generally
calls for a means to externally control bias when idling.
I also need to verify if SPE bypasses the antenna tuner in the standby mode.
I do know that the tuner must be auto-adjusted in standby and it's
impossible to bypass the tuner in the operate mode. So, its possible that
the added loss is occurring through the SPE's tuner while in standby.
Paul, W9AC
----- Original Message -----
From: "Phil & Debbie Salas" <dpsalas@tx.rr.com>
To: <amps@contesting.com>
Sent: Friday, February 12, 2010 2:42 PM
Subject: [Amps] QSK-5 insertion loss...
> "More investigation is needed as I came to the same calculated power
> dissipation for 1.5 dB of loss at 10m. I've validated my measurements on
> three separate devices into a Bird Terma-Line load but the QSK-5 does not
> appear to run unusually hot at 1KW from an SPE Expert amp. I'll report
> back
> when I find the root cause. Seems like this might be a good use for an
> industrial IR-detecting temperature scanner."
>
> Paul - I see that Ameritron rates the QSK5 at 1500 watts PEP, but 750
> watts
> continuous power. For greater than 750 watts continuous, they recommend
> an
> optional cooling fan.
>
> Phil - AD5X
>
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>
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