Cuz the amp is not designed to be loafed in the HV position, efficiency
sucks do to the much different plate load.
The LV position is a bit more efficient.
Why are you loafing an 8877 for anyway? Drive it with 50W and tune for max
in the LV position and then measure.
Carl
KM1H
----- Original Message -----
From: "Gary Smith" <Gary@ka1j.com>
To: <amps@contesting.com>
Sent: Wednesday, March 12, 2014 4:58 PM
Subject: [Amps] HV & temps
I have started working RTTY for the first time in 25 years (sending
using the CW paddle & having the K3 convert it to RTTY). I thought
I'd use the amp to give me a better signal and take it very easy on
the K3. I have a temperature probe in the air exhaust and it tells me
when the tubes are heated enough to fry an egg or not.
I had the amp set for 300 watts output using the higher volt setting
of 3,800V and saw the exhaust temps closing in on 180F pretty
quickly. After fiddling with the load plate settings I ended up with
pretty much the same results of high temps with low output power.
I then tried with the voltage in the low HV setting of 2,600V and for
the same 300 watts out, it takes a whole lot longer to get to a
higher temp.
Why would this be? With the higher V it takes less current & with the
lower volts it takes higher current to get the same wattage. Why does
using the higher voltage setting result in a hotter exhaust?
Gary
KA1J
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