Skanti TRP 9250, Техническое руководство, Страница: 154 / 289

2.2 Remove the front cover of the Transceiver Unit.
2.3 Locate and disconnect X10 carrying the 2. Local Oscillator signal from the
Synthesizer Board 911 to RX/EX Signal Path 715S. Connect the frequency
counter to the X10 socket on the synthesizer.
2.4 The ambient temperature should be within 10 to 30 deg. Celsius. Do not adjust
the Master Oscillator shortly after long keying sequences of the transmitter.
Be sure that thermal equilibrium has taken place before adjustment.
3. Realignment of Master Oscillator:
3.1 Locate the Master Oscillator adjustment hole in the metal shield of Synthesizer
Board 911. Use a small screwdriver to gently adjust the frequency.
3.2 Adjust the frequency as close as possible to 44.544 000 MHz.
Adjustment tol/-1Hz.
3.3 Connect X10 and refit the top cover.
Method 2: Realignment using the built-in ’Frequency Error’ test.
Note: A telex- or a narrow CW-filter must be installed before this method can be used.
Most AM broadcast stations have a frequency error in the order for 1 to 3 Hz and some have
extremely high accuracy as they are frequency locked to atomic standards.
As the necessary measurement time is shorter on higher receiver frequencies choose higher
frequencies for quick adjustment. The displayed frequency error of the equipment will be updated
every 4 seconds when frequencies above 16 MHz are received. Below 500 kHz the displayed
frequency error is updated every 256 seconds.
If the frequency accuracy of the received station is not known use the "Prog" "31" "Enter" feature
on several stations to get a general picture of the frequency error.
This function can also be used frequently to check the frequency error of the equipment.
1. Preparations:
1.1 Switch on the power at least 30 minutes before adjustment.
1.2 The ambient temperature should be within 10 to 30 deg. Celsius. Do not adjust
the Master Oscillator shortly after long keying sequences of the transmitter. Be
sure that thermal equilibrium has taken place before adjustment.
1.3 Remove the top cover of the Transceiver Unit.
1.4 Choose a strong AM or CW signal with know good frequency stability.
1.5 Enter as receiver frequency the exact carrier frequency of the station to be used.
1.6 If an AM broadcast station is used, select AM mode and observe that the signal
is received with not too strong fading and a reasonable signal to noise ratio. If
these requirements are not fulfilled choose another station.
SERVICE PREVENTIVE MAINTENANCE
5-4 TRP 9250 TECHNICAL MANUAL