Hi Al -
That works. Four measurements and two calculations.. :-) I used to lift the lead from the cathode feedthrough and insert a meter. Then I got "uptown" and now use an HP Clip-on Hall-effect meter on that lead.
Several more than one way to skin the proverbial ...
73, Garey - K4OAH
Al Parker wrote:
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: <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
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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