Eico 753 - ADJUSTMENT OF MICROPHONE GAIN

3a. If microphone is equipped with PTT switch, return MODE switch to SSB. Depress PTT
button on mike and adjust the CARRIER BALANCE control for a minimum meter reading.
NOTE
If this is the first time the 753 is placed in
operation, set the BIAS adjust on the rear
apron so that the minimum meter reading
obtained with the CARRIER BALANCE
control in 3a above is 50mA.
3b. If the microphone is not equipped with a PTT switch, return the MODE switch to SSB. Set
the FUNCTION switch at VOX. Leave the MIC GAIN fully ccw (but not past the detent).
NOTE
If this is the first time the 753 is placed in
operation, now adjust the rear panel VOX
controls as described in the NOTE of Step 2
in the subsequent MICROPHONE GAIN
adjustment.
While holding the relay in the transmit condition with a steady tone or sound into the microphone,
set the panel CARRIE R BALANCE control as described in step 3a (and the rear apron BIAS adjust,
as given in the NOTE following 3a, if this is the first time the 753 is placed in operation).
4. Reset the MODE switch at TUNE and adjust EXCITE R tune and PA TUNE as described in
steps 1 and 2. Slowly turn the PA LOAD control cw and "dip" meter reading with PA TUNE control
until the meter reads between 250 and 300ma. Reset MODE switch to SSB. This completes proper
tuning and loading of the transmitter.
NOT
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Tune-up procedures should not be prolonged
more than Wseconds in any one adjustment
period to avoid excessive heating of compo-
nents in out-of -resonance conditions.
ADJUSTMENT OF MIC ROPHONE GAIN
1. For push-to-talk operation, set FUNCTION switch at PTT. Depress mike PTT· button and
turn MIC GAIN control cw while speaking until the average meter reading is between 100 and 150ma.
As the MIC GAIN is advanced further cw, a point will be reached where the average meter reading
with uninterrupted speech will hover around 150ma. When this occurs, peaks .will actually be in the
300ma region. If the MIC GAIN is advanced past this point, the average meter reading will not in-
crease because of the ALC action. Do not turn the MIC GAIN clockwise past the point where there
is no increase of the average meter reading on normal uninterrupted speech, as doing so will not
increase output power but simply result in excessive gain and unnecessarily increased noise.
2. For VOX operation, turn the FUNC TION switch to VOX. Set the MIC GAIN control fully ccw
(but not past the detent).
NOTE
If this is the first time the 753 is placed in
operation, now adjust the rear apron VOX
controls as follows (unless they have already
been adjusted as required in the NOTE of
step 3b, in the previous TRANSMITTER
TUNE -UP FOR SSB OPE RATION procedure).
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