1.
Set the transceiver up in the receive condition and apply an input signal to the ANTENNA
connector. The signal may be on any frequency in any of the three bands covered. Tune the trans-
ceiver to this signal and set the RF GAIN control so that, at maximum, the S-Meter reads S-9.
2.
Upon tuning slowly past the signal, the S-Meter should indicate two peaks, both on the same
side of zero-beat.
If
the RF gain control has been set so that, at each peak, the reading is S-9, then
at zero beat the meter should read between S3 and S4.
If
this is not the case, or if both peaks do not
yield equal S-readings, proceed to step
(
3). Otherwise, the filter is in proper alignment and no adjust-
ments should be made.
3.
Tune the receiver to a point midway between the two peaks, and adjust the slug of T2 for
maximum S-Meter reading. Repeat step (2) above.
If
the filter is still not in alignment, offset the
slug of T2 slightly, and repeat the measurement. The setting of this coil will be quite critical and
its adjustment must be made caref ully.
If
it is not possible to achieve a reasonable pass-band by
adjusting T2, set T2 for a maximum S-Meter reading midway between the two peaks and proceed to
step (4).
4.
Repeat the procedure in step (3), only this time adjust the slug of transformer
Tl
on the crystal
filter assembly. Exercise caution in making this adjustment since too great a misalignment of this
coil will cause the pass=band to widen, thereby reducing selectivity and sideband suppression.
It
will
be possible to properly align the filter by repeating steps (3) and (4) several times until the desired
pass-band is obtained. No adjustment of L
l
will be necessary.
DC VOLTAGE AND RESISTANCE CHART
The following chart lists the approximate DC voltages and resistances to ground at each of the
ter minals of those tube sockets which are chassis mounted, and is off ered an an aid in troubleshooting.
Reasonable deviations from the values given should be expected and cause no concern, since compo-
nent values will vary within their allowable tolerances to produce such deviations.
Three tables are listed. The first, Column A, lists the DC resistance to ground from each
tube socket pin. These values are to be measured with no external connections to the transceiver,
meaning that the power supply, speaker , antenna, microphone, etc. , are all disconnected. For the
DC voltages, Columns B and C , only the power supply is connected to the unit. The readings given
are those to be expected when using the EICO Model 751 AC power supply under normal ( 1l7V) line
voltage conditions. In all cases, the front panel controls are to be set as indicated below:
Column A:
FUNCTION SWITCH.
. . . . . ...... . .
.
.
.OFF
MODE SWITCH.
..
.
. . . . .
.
. .....
.
. ...
SSB
CARRIER BALANCE
. .
.
. .. ....
.
. ...
.mid-rotation
PA TUNE
. . .
. . .
. . .
.
.
.
. . . . . . . . . . . . .
.mid-rotation
EXCITE R TUNE .
. . . . . . . . . . . . . . . . . . .
mid-rotation
RC VR OFFSET
. . . . . . . . . . . . . . . . . . . . .
mid-rotation
MIC GAIN
. . . . . . . . .
..
. . .
. .
. .
. .
.
.
....fully
ccw
(but not past
detent)
RF
GAIN
. . . .
. . ... ...
.
•
. ... .
.
....
...fully
ccw
A F GAIN
. . .
.
..
. . .
.
. . . . . . . .
.
. . . . . . . .
fully ccw
PA LOAD.
.
. .
. . .
. .
. .
. . . ... .... . ... .
fully ccw
Column B:
Same as for Column A, except FUNCTION switch is set at PTT
Column C:
Same as for Column B, except that a microphone with PTT switch is connected, and
the PTT button is depressed; also, the MODE switch is set at CW.
Voltage checks are made with a vacuum-tube voltmeter having an input impedance at the probe
of 11 meghoms. The heater voltages on the var ious tubes are listed as AC , since the 751 AC power
supply is being used to power the unit for measur ement purposes.
17
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