Date: Mon, 12 Dec 2016 20:50:04 +0200
From: Vic Rosenthal 4X6GP <k2vco.vic@gmail.com>
To: Amps reflector <amps@contesting.com>
Subject: [Amps] TL922 efficiency
I suspect my measurements are incorrect, and possibly someone with
another TL922 can give me a sanity check.
On 40 meters, I am measuring the following into a dummy load:
Output: 1200 watts (several reliable wattmeters agree).
Drive: 65 watts.
Grid current: 200 ma.
Plate current: 580 ma.
Plate voltage 2600 V under load (3 kV no load).
Zero signal plate current: 140 ma.
This represents an input power of 1508 watts. If I assume that 60 watts
of the output is fed through from the input, then 1140/1508 = 0.76, or
76% efficiency. I find this hard to believe. I am wondering whether the
plate current or voltage measurement is wrong.
My amp has the grids directly grounded, if that means anything.
What do others see from TL922's?
--
73,
Vic, 4X6GP
Rehovot, Israel
Formerly K2VCO
## My guess is the plate current meter is reading way too low. I never
subtract the
drive power or a portion of the drive power, from the PO.
## I get on my L4Bs...
800 ma plate current
300 ma grid current.
2500 vdc under load.
110 watts of drive.
1290 to 1320 watts output
This is on 40M.
64-68% eff is typ on 40m with most GG amps.
Jim VE7RF
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