Eico 753 - TRANSMITTER ALIGNMENT; CRYSTAL FILTER

ALIGNMENT PROCEDURE
Before proceeding with the alignment, the transceiver should be removed from the cabinet and
the cover should be removed from the VFO compartment. In removing the latter , it will be necessary
to temporarily remove the fibre extension shaf t from the P. A. tuning capacitor. The shaf t should be
reinserted af ter the VFO cover is removed.
A 40 to 80 ohm dummy load capable of dissipating at least 125 watts should be available. A 100
watt light bult may be substituted for the dummy load if necessary. Some means of measuring relative
H. F. power output to the dummy antenna should also be provided. An R. F. ammeter or an in-line
watt meter will be helpful toward this end.
Three reference signals from a well calibrated VFO or crystal oscillator will be necessary.
These are 7. OOMc, 7. 30Mc, and 3. 80Mc. VFO alignment should not be attempted unless the signal
source is well calibrated. If a calibrated communications receiver is available, it may be used to
set the external source. In any case, a crystal oscillator is to be pref erred.
RECEIVE R ALIGNMENT
a) IF Strip
1. The transceiver should be connected to the EICO 751 (or 752) power supply. There
should be no microphone connected to the unit at this time. Before turning the unit on, set the controls
as follows:
MIC GAIN . . . . . . . • . . . ... . . .fully ccw (but not past detent)
R F GAIN . . . . . . . . . . . . . . . . . . fully ccw
A F GAIN . . . . . . . . . . . . . . . . . . fully ccw
CARRIER BALANCE . . . . . .. . . . mid-rotation
MODE SWITCH . . . . . .. . . • . . .SSB
FUNC TION SWITCH . . . . . . . . .OFF
MAIN TUNING FREQUENC Y. . . . . . . . . . 7. OOMc
PA TUNE . . . . . . ... . • . . . . . . .Mid- rotation
BAND SWITCH. . . . . • • . . . . . .40 meters
PA LOAD. . . . . . . . . . . . . . . . . . fully ccw
RC VR OFFSET . . . . . . . . . . . . .mid-rotation (at centerline)
EXCITE R TUNE . . . . ... . . . . . mid-rotation
NEUTRALIZING CAPACITOR C 107. . . . . . . . . . fully un-meshed
2. Connect a small capacitor (between 20 and 50pf ) from pin 3 of V4 to pin 7 of V l7. This
is a temporary measure and is best done with a pair of clip leads.
it at PTT.
3. Set the FUNC TION switch at STANDBY, and af ter one or two minutes of war mup, reset
4. Advance the RF GAIN control to the fully cw position, and adjust the slugs of IF coils
T3, T4, and T5 for maximu m S-Meter reading.
5. Return the RF gain control to its fully ccw position, and turn the FUNCTION switch to
OFF. Disconnect the clip leads installed in step (2).
This completes the IF strip alignment.
b) VFO
1. The controls are set as in step 1 of part (a).
2. Set both trimmer capacitors C40 and C42, on the VFO board, to mid-rotation.
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