Technical Manual

120 20170-201 Paragon
PD
Technical Manual
49
6.4.3 Exciter Module (T857, T837 or T881)
Note 1: Refer to Figure 33 (T857) and to Figure 35 (T837) for locating tuning controls and com-
ponents. T881 series II will be included in a later release.
Note 2: When the synthesizer is unlocked, the front panel green LED called "Supply" will flash
indicating that it needs re-tuning.
Warning: The LED will also flash when the unit is in setup mode while connected to the
PGM800win program.
6.4.3.1 Initial Setup
1. Shut down power to the base station
2. Prepare the multimeter to DC Volts.
3. Remove the exciter (T857 or T837) module from the base station rack frame
4. Remove the exciter top cover (nearest the handle).
5. Connect a 3 feet long double shielded cable (N-M to BNC-M) between the IFR T/R out-
put and the exciter antenna connector.
6. Connect the Paragon
PD
Extender Rail Kit to the empty chassis exciter slot.
7. Apply power to the base station
6.4.3.2 Synthesizer Alignment
Single channel: Connect the multimeter to the long lead of L1 in the VCO (this measures the
synthesizer loop voltage).
1. T857 (UHF) Tune VCO trimmer C6 for a synthesizer loop voltage of 10V DC.
2. T837 (VHF). Tune VCO trimmer CV1 for a synthesizer loop voltage of 9VDC.
Multiple channels:
1. T857 (UHF) Adjust the VCO loop to 10V using the middle channel.
2. T837 (VHF) Adjust the VCO loop to 9V using the middle frequency channel.
All channels should lie within the upper and lower limits of 16V and 3V respectively for
the T857 and within 13V and 5V for the T837.
Note:
Normally, the fast TX key option is installed and the synthesizer is always ener-
gized. In the case where that option was not fitted, key the transmitter by pressing
the front panel Carrier button to make the above adjustment possible.
6.4.3.3 TX Frequency Error Adjustment
1. Apply the following settings to the IFR:
- Receiver mode
- IFR RX frequency to match the main radio TX frequency
- IF Filter set to 30KHz
- Zoom the RF Error window: select 10Khz range