Adjustments 7-2 X-2 Technical Service Manual
Publication No: 15-02047
104-02908
2. On the PA PCB:
• +5V regulated DC supply selected in transmit only (IC2) +5 V
± 0.4 V. No test point provided but it can be checked at a number
of places. For example: R11
[F2]
or PTC R22
[E4]
.
• Zener shunt controlled DC supply to IC1
[C4]
(V1) +5 V ±0.25 V.
This can be checked at pin 5 of IC1.
7.4 Crystal Oven
108-04840
The Crystal Oven, on the Rx/Exciter & Control PCB, is attached to the
Reference Crystal Z3
[D3]
. The oven should be checked after allowing five
minutes warm-up period. The temperature operates between 50°C to 65°C
and is not adjustable. Replace if the results are outside the specified limits.
7.5 Test Mode
The X-2 Transceiver is provided with a special Test Mode to assist in the
following procedures:
• Alignment of the 45 MHz roofing filter using only an Oscilloscope, a
Signal Generator and a simple jig made from an 18 Ω resistor and 470
µF capacitor attached to clip leads.
• Alignment of the T5 and T6 in the 455 kHz IF circuit.
• Checking of VCO1 (not adjustable).
• Checking and adjusting of VCO2.
• Adjustment of the USB channel frequency.
• Adjustment of the LSB channel frequency.
• Checking the PA. The band switching, the intermodulation distortion at
the top, bottom, and centre of each filter band.
• Adjustment of receiver sensitivity at 15 selected frequencies between
2 MHz to 18 MHz.
To select the Test Mode:
1. Switch off the Transceiver.
2. On the Rx/Exciter & Control PCB , remove the shorting link parked
on the two ground pins of Link 1 and 2 and fit to Link 1.
3. Switch on the Transceiver, which is now in the Test Mode.
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