Model 686C Section IV
Paragraph 4-6 cont'd
-
POWER METER
. ._ ~
ACCURACY 5 .2db
Y Lo-L-aII
ACCURACY *2% OF READING
90" ELBOW 6" LONG MAX
I
Figure 4-1. Measuring RF Output
3) Turn on equipment and adjust for rated cw output. B. FREQUENCY DIAL CALIBRATION
(See figure 2-1 for recommended turn-on procedure. )
1) Connect a wavemeter and detector system to the
sweep oscillator as shown in figure 4-2. The use of
4) Allow 15 minutes for the Sweep Oscillator and the
@ Model 430C Power Meter to stabilize. three wavemeters is a convenience, not a necessity.
When one wavemeter is used, change its setting for
5) Reduce power output to zero with the CATHODE each frequency check.
CURRENT control and zero-set the power meter on 2) Adjust the Sweep Oscillator for rated cw output.
the 3 milliwatt range.
3) Tune the wavemeters to 8.2, 10 and 12.4 kmc.
6) Reset CATHODE CURRENT value at designated
frequency. Rotate SWEEP SELECTOR to RECUR, A FREQUENCY
to 14 and SWEEP RATE to lk.
7) Rotate the FREQUENCY dial slowly from one
4) Rotate the FREQUENCY dial to the checkpoints
end of the band to the other and note power change. and watch for the wavemeter pip. Turn the FRE-
The change should not exceed kl.5 db for the full band.
A thermistor mount with low swr must be used to ob- QUENCY dial until the wavemeter pip has moved to
the start of the rf sweep. Dial reading should agree
tain maximum accuracy. within *l% of the wavemeter reading.
NOTE
NOTE
The power output can be severely reduced
by use of excessive lengths of flexible wave- When more than one wavemeter is used, the
guide or even short lengths which are not in wavemeter tuned to the low-frequency end
good mechanical condition. Any discontinui- may also resonate near the high-frequency
ties will cause reflections in the system. The end. If there are two pips at the high end,
attenuator must have very constant attenuation the true pip may be identified by "rocking"
across the band. The X382 has excellent the high-end wavemeter: move its frequency-
accuracy. It is also possible to use a 10 db setting control back and forth a few degrees
directional coupler such as an @ Model X752C while watching the oscilloscope. The true
for an accurate attenuator. high-frequency pip will move.
00034- 1 4- 3 |
ACEC
