Tait T860 Series II, Service Manual

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D3.4 T869 Initial Adjustment
M860-00-Preliminary
30/06/98 Copyright TEL
Check that the regulated power control supply is approximately 7V.
Note: The output power and alarm levels should be set with the cover shield on.
If the cover is removed for other adjustment procedures, make a final check
of the output power and alarm levels with the cover shield on.
3.3 Setting The Output Power
Caution:
If the temperature shutdown power level has not yet been set or is
unknown, check that the unit does not overheat while setting the out-
put power.
Note 1: Cables and connectors can easily cause a power loss of several watts if either
too long or poorly terminated. Always use the shortest possible leads (or
connectors instead of leads) between the T869 and power meter set-up.
Note 2: You will need appropriate extension leads if you wish to carry out the
adjustment procedures with the T869 withdrawn from the rack in the
latched position. Alternatively, disconnect and withdraw the T869 and
reconnect it behind the rack.
Note 3: The actual power used may be limited by regulatory requirements.
Connect the exciter output to the PA input via a thru-line wattmeter with a 1W
full scale reading. Special BNC/N leads will be required.
Connect an RF power meter to the PA output. Set the front panel power control
preset (RV63) and the driver power clamp (RV69) fully clockwise.
Key on the drive source.
Check that the power output exceeds 120W.
Note: If the output power level is low, check that the temperature shutdown cir-
cuit has not activated by verifying that IC3 pin 8 is low.
Adjust RV69 to reduce the maximum power output to 110W.
Adjust RV63 to set the power output to the required level (e.g. 100W).