Floyd,
The procedure for calibrating meter indicated Ip and Ig on the 422 multi-meter
is:
1. Insure that the unpowered meter is mechanically zeroed.
2. Unplug cable #4 located on the HV Rectifier-filter board (81538).
3. Feed 2.2vdc + to pin3 ,- to pins 1 and 4 of cable #4.
4. Select Ig metering mode, and adjust R3 (on display board 81540) for 240 ma
meter indication.
5. Select Ip metering mode, and adjust R1 (on display board 81540) for 800 ma
meter indication.
This procedure only calibrates the display board Ip and Ig metering circuit
components.
The values of the resistors in the source networks (located on the 81538 HV
RECTIFIER-FILTER board) should be checked to confirm that source data for the
display-board metering circuits is correct/accurate.
I calibrated the Ep meter value by measuring the plate voltage with a HV probe,
and adjusting R2 on the display board accordingly. I adjusted R4 and R5 to
achieve meter readings consistent with external wattmeter readings.
Hope this helps. If you can't achieve the prescribed Ip and Ig meter readings
per this procedure, chances are that the meter movement is kaput...and, that
would be a very bad outcome. The meter is a custom "vane" type (not
D'arsonval), and my search for a replacement was unsuccessful.
Good luck, and 73...
Allen--W7GIF
----- Original Message -----
From: Floyd Sense<mailto:k8ac@k8ac.net>
To: tentec@contesting.com<mailto:tentec@contesting.com>
Sent: Wednesday, September 28, 2016 8:20 AM
Subject: [TenTec] Tentec Centurion meter adjustment document?
A while back, I ran across some online documentation describing the
procedure that Tentec technicians used to calibrate the Centurion
meters. I failed to print it out at the time, and now can't locate it
again. Can anyone point me to that document? My memory is sketchy on
this, but as I recall the document instructed the technician to apply a
specific DC voltage to the various pins on the Display Board and to
adjust the 5 pots on the board for specific meter readings at those
voltages.
73, Floyd - K8AC
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