From: "Gerry" 
Subject: RE: [drakelist] T-4XB apparent vs actual plate current


52 ma seems like in the ball park. Those meters were "probably" +/- 5%, a
typical figure for that vintage meter. If I remember correctly, Drake didn't
use precision resistors for shunts and multipliers. Your DMM is certainly
many more times accurate than the meter movement ever was in the first
place.

-----Original Message-----
From: owner-drakelist{at}www.zerobeat.net
[mailto:owner-drakelist{at}www.zerobeat.net] On Behalf Of W5EI{at}cs.com
Sent: Wednesday, March 03, 2004 12:47 PM
To: drakelist{at}www.zerobeat.net
Subject: [drakelist] T-4XB apparent vs actual plate current


OK, Garey-I checked the meter, and it showed .16 volts thru the connections
on the back of the housing.  The shunt resistor measures 3.1 ohms in
circuit, and 3.3 ohms out.  Using the 3.1 ohm figure, that would make the
actual current around 52 mA.  This is with the pot on the back of the AC-4
set to read an apparent 70 mA on the meter.  Assuming my cheapie DMM is
anywhere near accurate, I am seeing a significantly higher appparent vs
actual plate idle current reading.  I looked through the T-4XB manual, and
did not find anything specific as to meter calibration.  What is the usual
cure for this situation?

On the bright side, the AC ripple in the transmit signal is now gone with
the replacement of the old C4 cap in the AC-4 PS.

73,

Don, W5EI
Troup, TX    
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