Yes, those numbers are about right Peter.
On that much larger allowable linear plate swing on the tetrode, that
characteristic and efficiency difference is also evident on my valve HiFi
amplifier using the "Kinkless Tetrode" KT88 tubes in Ultra-linear P-P.
When I switch the screens from their normal 43% UL taps on the output
transformer to "triode" mode by strapping them to the plates, one observes
the said much lower Po and efficiency...but with a completely different
distortion in IMD spectrum...that some critical listeners prefer.
Leigh
VK5KLT
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of peter chadwick
Sent: Friday, 1 November 2013 4:24 AM
To: TexasRF@aol.com; keepwalking188@yahoo.com; dezrat1242@yahoo.com;
amps@contesting.com
Subject: Re: [Amps] GS23B Plate load resistance for HF
Assuming 3kV on the plate, 500 volts on the screen and AB1 operation in
grounded cathode, I calculate a PEP output of 1540 watts, a dissipation of
1240 watts, efficiency 55% and a load resistance of 1570 ohms - calculation
method as per RCA. Peak plate voltage when loaded is 3700 volts.
The 4CX1000A has a much bigger allowable plate swing before the plate
current curve starts to bend - which helps the efficiency.
73
Peter G3RZP
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