Icom IC-230 Instruction Manual page 7

3.7 СО Spare Crystal Socket |
There is a spare crystal socket along with the 10 installed crystals in the CO module.
The spare socket is for "С" on the 10 KHz Selector for both 146 and 147 MHz. This
crystal adds 7 channels with 300 KHz separation.
The frequencies are całculated as follows.
f (MHz) = Desired Operating Freq. — (LO, _„ Freq. x 9) — 10.7 (MHz)
For example, if you desire to operate on 146.05 MHz
f (MHz) = 146.05 (MHz) — 13.783 (MHz) x 9 — 10.7 (MHz) = 11.305 (MHz)
If you put a 11.305 MHz crystal into the CO spare socket, 7 frequencies with 300 KHz
separation will be produced. They are 146.05, 146.350, 146.650, 146.950, 147.250,
147.550 and 147.850 MHz.
To order additional crystals from a manufacturer, the following correlation data is
provided. Remember to specify high activity as prerequisite to your acceptance.
Crystal Data
Holder Type: HC-25/u
Calibration Tolerance: 0.0025%
Load Capacitance: 20 pf
Effective Resistance: 15 ohms or less
LO Frequency: 13.783 — 13.983 MHz
CO Frequency: 11.265 — 11.535 MHz
Cut: "AT" optimum angle +2 min.
Due to the 30 kHz separation in the United States, not all selectable frequencies are available.
If the meter light goes out after selecting a frequency, you will know that that frequency is
outside the 30 KHz separation.
3.8 External Speaker:
An external speaker jack and plug is supplied with your unit in the event another speaker
is desirable. The external speaker impedance should be 8 ohms. The use of the external
speaker jack will disable the internal speaker. An 8 ohm headset can be utilized as well.