From: "Al Parker" 
Subject: Re: [drakelist] T-4XB apparent vs actual plate current


Hi Don,
    If you measure the final cathode resistors (accurately), and measure
the voltage directly across them when at idle, you can calculate the
actual final current probably more accurately than  the way you've done it
(remember, they don't go directly to gnd).  That's the way I do it when
ckg/fixing meter accuracy.  I thought you had mentioned earlier that you
had ckd the screen & cathode resistors, replaced the screens', but I can't
find that msg now.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
http://www.hammarlund.info


----- Original Message ----- 
From: 
To: 
Sent: Wednesday, March 03, 2004 12:47 PM
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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