Alignments

This page shows the alignment instuctions for the Cybernet UK 27/81 radio's
Using the PTBM 134 AOX PCB


PLL Alignment

Make sure that the delta tune is set to "0".

Connect a frequency counter to the base of Q-10.

Adjust CT-2 for a reading of 10.24046 +/-50Hz.


VCO Adjustment

Ensure that the set is in RX,on CH 40.

Attach a DC voltmeter to TP-1.

Adjust T-1 for a reading of 4.0 V +/- 0.1 V.

Change to TX ,then adjust CT-1 for a reading of 4.0 V +/- 0.1 V.

Change to CH 1,TX,and make sure that a reading of between 1.8-2.5 V is obtained.

Change to RX,make sure that a reading of between 1.9-2.5 V is obtained.


TX Alignment

Set the power supply voltage to 9 Vdc.

Attach a oscilloscope to the ant socket.

Put the set on CH 20.

Adjust T-2,T-3,T-4 for the maximum wave form on scope.

Turn the power supply voltage up to 13.2 Vdc, and make sure the radio is set to high power.

Adjust L-4,L-8,L-9 for maximum reading on watt meter.

Rotate L-4 clockwise to obtain 4.4 W.

Rotate L-9 counterclockwise to obtain 3.8 W.

Ensure that the power output difference on CH 1 and CH 40 is within 0.3 W.

Put the set to lo power,and change the power supply voltage to 15.6 Vdc.

Adjust RV-5 for a reading of 0.5 W.

Change to CH 40,TX.

Apply 20 mV/1.25kHz audio to mic input jack.

Adjust RV-6 for maximum deviation.

Adjust RV-2 to exactly 2.15 kHz deviation.

Adjust RV-6 to exactly 1.6 kHz deviation.

Remove audio from audio input jack.

Adjust RV-4 that the set's RF meter reads the same as the external RF meter.


RX Alignment

Attach signal generator to ant socket and set its output for 27.79125 MHz without modulation.

Attach a DC Volt meter to TP-2.

Adjust T-5,T-7,T-8,T-9,T-10,T-11 for maximum voltage, then rotate T-5 1/2 a turn clockwise.

Add a 1 kHz audio signal with +/-0.8 kHz deviation.

Attach an oscilloscope to the speaker.

Adjust T-12 for maximum reading on oscilloscope.

Set the RF signal generator to provide 100 āV (40dB).

Adjust RV-3 so that the signal meter reads "S-9"


If you have not checked out my modifications page for this radio Go And Take A Look


This counter shows the number of hits since the 19th September 1998


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