Bird Technologies 4331 - Manual (Page 62)

will also be noticed upon transmitter de-energization as the meter needle
sweeps back to zero. Also, the meter reading may be expected to waver
approximately 2-3 minor scale divisions when voice modulation is used as
the peak detector attempts to follow peak power variations associated with
voice modulation.
Model 43P Peak Calibration
If it is felt that the peak readings are questionable, or for any reason
recalibration is required, proceed as described.
Remove the rear cover, follow these instructions.
1. Remove the four 8-32 Phillips flat head screws that se-
cure the rear cover. There are two on either side of the
meter housing.
2. Pull the cover straight off.
Refer to figure 15 for the following calibration instructions:
1. Insert the Model 43P between an RF (CW) signal source
and a 50 ohm load.
2. Insert an element for the appropriate power and fre-
quency range into the Model 43.
3. Turn the element in the direction to read forward power.
4. Place the mode switch, on the side of the Model 43P, in
the CW position (LED off).
5. Turn on the signal source.
6. Adjust power to give a stable reading on the Model 43P
Wattmeter in the upper half of the scale.
7. Switch to the PEAK mode (LED on).
8. The RF power reading should remain the same. If it does
not read the same, adjust potentiometer (R9 -top center
of the PC board) until the PEAK reading is the same as
Bird Model 43 Wattmeter
48