[TenTec] Tentec Centurion meter adjustment document?

[Floyd Sense]

Thanks for the info, Allen.  I'll give that a try and see how close the meters are.  Since there are adjustment pots in series with the meters for each function, the most accurate approach would probably be to pass a current through the shunt resistors from an external supply, adjusted to the full scale meter readings, then adjust the series pots to read that value full scale.  Haven't checked the shunt resistor values yet, but since the amp is now 25 years old, I'd suspect they've drifted up in value a bit.  Will also check the dividers for the HV metering.

73, Floyd - K8AC







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