Greetings everyone
I hesitate to use my KPA-500 here at this CN98pi QTH. LIne frequency here
varies daily between 58.xx-to-61.yy Hz and line voltages vary between
110-to-130VAC due to the limitations of the governor controlling the
communities 200KW hydro system (Chelan County PUD remote facility).
When the refrigerator motor 'groans' I know the line frequency is
approaching 58-plus Hz and the system may crash if the auxiliary 75KW
diesel generator is too slow to pickup an instantaneous heavy load !!
I do NOT want to chance destroying my KPA-500 here, so only use it when at
CN97uj where line frequency variations amount to +/- 0.001Hz as displayed
in the PUD's main control room !
73 Dick/w7wkr
===========================
Message: 16
Date: Wed, 6 Jul 2022 12:53:12 +0000
From: Andy Durbin <a.dur...@msn.com>
To: "elecraft@mailman.qth.net" <elecraft@mailman.qth.net>
Subject: [Elecraft] KPA500 Voltage range?
Message-ID:
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"My kpa500 has the taps set to provide 71-72 VDC no load and drops to 60 at
500 watts."
Do you know how your house line input voltage varies? Mine can be as high
as 122 and as low as 118 and the local transformer is less than 50 ft from
my house.
I see unloaded KPA500 voltage over 80 with tap selected to keep loaded
KPA500 voltage at or above 60. If your loaded voltage does not drop below
60 for all bands, all antenna loads, and all used output powers, I see no
reason to change the tap. Band, loading, and power output all have a very
significant influence on efficiency, PA current, and voltage drop in the PA
HV supply.
Spot check values:
Line voltage 122.0
Unloaded HV 81.4
TX 500 W, 6 m band, SWR 1.15, HV 60.3
Andy, k3wyc
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