Technical Manual

120 20170-201 Paragon
PD
Technical Manual
50
2. Key the transmitter by pressing the front panel TX-Key button and measure the carrier
output frequency. It should be within ±300 Hz. If it is not, adjust the TCXO to trim to
meet the requirement, preferably within 100Hz.
6.4.3.4 Low-Frequency Balance Adjustment
PGM800Win controls this adjustment. Electronic potentiometer (256 step) is used to allow
channel adjustment of two-point modulation (Low freq. balance).
1. Apply the following settings to the IFR:
– Receiver mode and Oscilloscope display (Source Demod out connector, DC cou-
pled).
– IFR RX frequency to match the radio transmit frequency
– IF Filter set to 30KHz
– Zoom the Deviation window: select 10kHz Range and DC coupling.
2. Select the active or, the lowest (in the case of multi-channel base) frequency channel (via
dip switch)
3. Transmit a square wave by pressing the BDLC
PD
’s PF1 button and following the proce-
dure outlined in section 3.2.1.1.2.2. You can also run both programs on the same com-
puter if two serial COM ports are available.
4. Adjust IC220 via PGM800Win “reference modulation” to obtain the best square wave,
no damping, no overshoot. (You can use either the mouse or up and down arrow keys).
Record the deviation read.
5. If transmission has not ended by itself, press BDLC
PD
PF1 to stop it. For single-channel
unit, proceed to step 8.
6. For multi-channel unit, select the highest frequency channel. Transmit a square wave by
pressing the BDLC
PD
’s PF1 button and following the procedure outlined in section
3.2.1.1.2.2. Record deviation again.
7. The difference in deviation between the two channels should be less than ±300Hz. If not,
re-adjust IC220 to "average" the square wave shape on both channels until the spec is
met.
8. To confirm the adjustment, select the active, or the lowest frequency channel. Compare
the deviation produced between:
- 1000 Hz sine wave adjust tone and
- Random data
The difference should be lower than 300 Hz. For multi-channel unit, repeat this step on
the highest frequency channel.
8. Select the active channel. Transmit a TX ON (Modulated) adjustment tone by pressing
the BDLC
PD
’s PF1 button and following the procedure outlined in section 3.2.1.1.2.2.
Make sure that deviation level read on the IFR correspond to model and bit rate in use
(see Table 8 – Carrier deviations for Tone or Data Modulation). Re-adjust deviation as
necessary referring to the related Checklist (B for Paragon
PD
- page 27