User's Manual

120 20170-200 Paragon

Technical Manual35

6.2.3 Exciter Module (T881)

Note 1: Refer to Figure 22 on page 39 for locating tuning controls.

Note 2: When the synthesizer is unlocked, the front panel green LED called "Supply" will be flashing

showing that it needs to be re-tuned.

6.2.3.1 Initial Setup

Shut down power to the base station

Prepare the multimeter to read DC Volts.

Remove the exciter (T881) module from the base station rack frame

Remove the exciter top cover (nearest the handle).

Connect the Paragon

Extender Rail kit between the exciter module and the empty chassis exciter

slot.

Connect a 3 feet long double shielded cable (N-M to BNC-M) between the IFR T/R output and

the exciter antenna connector.

Apply power to the base station

6.2.3.2 Synthesizer Alignment

Single channel: Connect the multimeter to the long lead of L1 in the VCO (this measures the syn-

thesizer loop voltage). Tune VCO trimmer C6 for a synthesizer loop voltage of 7VDC.

Multiple channels: Adjust the VCO loop to 7V using the middle frequency channel.

All channels should lie within the upper and lower limits of 10V and 3V respectively.

Note: Normally, the fast TX key option is installed and the synthesizer is always energized.

Where that option was not fitted, key the transmitter by pressing the front panel Carrier

button to make the above adjustment possible.

6.2.3.3 TX Frequency Error Adjustment

Apply the following settings to the IFR:

Receiver mode

IFR RX frequency to match the main radio TX frequency

IF Filter (BW) set to 30KHz

Zoom the RF Error window: select 10Khz range

Key the transmitter by pressing the front panel TX-key button and measure the carrier output fre-

quency. It should be within ±300 Hz. If it is not, adjust the TCXO to trim to meet the requirement,

preferably within 100Hz.