User's Manual

5-6
this frequency. To tune this frequency, enter 118010 into the transceiver. The entered value is
what will be displayed even though the transceiver will be operating at 118.0083 MHz.
In a similar fashion, line 4 of the chart shows that the next available frequency is 118.0166
MHz. This also is only allowed to have a channel spacing of 8.33 kHz. But to operate at this
setting, enter 118015 to the transceiver.
Lines 5 and 6 of the chart show that the process repeats at this point.
If the user attempts to enter a frequency that is not allowed, the transceiver will simply not
accept the input until a valid value is entered.
Aviation Mode Frequency Chart
Line
Number
Frequency
Entered
(MHz)
Actual
Operating
Frequency
(MHz)
Channel
bandwidth
(KHz)
1 118.000 118.0000 25
2 118.005 118.0000 8.33
3 118.010 118.0083 8.33
4 118.015 118.0166 8.33
5 118.025 118.0250 25
6 118.030 118.0250 8.33
7 118.035 118.0333 8.33
8 118.040 118.0416 8.33
9 118.050 118.0500 25
10 118.055 118.0500 8.33
11 118.060 118.0583 8.33
12 118.065 118.0666 8.33
13 118.075 118.0750 25
14 118.080 118.0750 8.33
15 118.085 118.0833 8.33
16 118.090 118.0916 8.33
17 118.100 118.1000 25
18 118.105 118.1000 8.33
19 etc. etc. etc.
5-3.4. TUNING INCREMENT VS. CHANNEL SPACING, ELECTRICAL CHARACTERISTICS
The terms “tuning increment” and “channel spacing” are often misinterpreted. By definition:
 The “tuning increment” is the minimum incremental change in operating frequency of which a
transceiver is capable.
 The “channel spacing” is the window (or the bandwidth in kHz) that a tuned transceiver will
operate in and represents the minimum acceptable adjacent channel separation. This
window or bandwidth is determined by the receiver’s IF selectivity (bandwidth). In the URC-
200 (V2), whether the tuning increment is 5kHz, 12.5kHz, 8.33kHz, or 25kHz the IF selectivity
does not change. (The IF selectivity specifications for the URC-200 (V2) is outlined in
Table 1-1 of this manual.
NOTE
Exercise care when communicating between various transceivers.
If a 5kHz,
8.33kHz, or 12.5kHz tuning increment is used, the URC-200 (V2) Transceiver could
receive an adjacent channel’s signal. Depending what the channel spacing
specification is of the adjacent channel transceiver, the URC-200 (V2) Transceiver
may not be able to communicate back to it unless it is re-tuned to the on-channel
frequency of the adjacent channel transceiver.