External Speaker - Icom IC260-A Instruction Manual

ANTENNA
The most important single item that will influence the performance of any communication system
is the antenna. For that reason, a good, high-quality, gain antenna of 50 ohms impedance is
recommended, fixed or mobile. In VHF as well as the low bands, every watt of ERP makes some
difference. Therefore, 10 watts average output plus 3dB of gain antenna equals 20 watts ERP,
presuming low VSWR of course. The few more dollars invested in a gain type antenna is well
worth it. When adjusting your antenna, whether mobile or fixed, by all means follow the manu-
facturer's instructions. There are some pitfalls to be aware of. For example, do not attempt to
adjust an antenna for lowest VSWR when using a diode VSWR meter not engineered for VHF
applications. Such readings will invariably have an error of 40% or more. Instead, use an in line
watt meter similar to the Drake WV-4, Bird Model 43 or Sierra Model 164B with VHF cartridge.
Further, when adjusting a mobile antenna, do so with the motor running preferably above normal
idling speed. This will insure proper voltage level to the transceiver.
The RF coaxial connector on the rear chassis mates with a standard PL-259 connector. Some
models may have metric threads. In any event, the RF connector will mate with almost any
PL-259 connector if care is taken to seat them properly.
MICROPHONE
A high quality dynamic microphone with built-in preamplifier is supplied with your transceiver.
Merely plug it into the proper receptacle on the front panel. Should you wish to use a different
microphone, make certain it has a proper preamplifier. Particular care should be excercised in
wiring also, as the internal electrics switching system is dependent upon it. See the schematic for
the proper hook up.
Microphone plug exploded view Microphone connection
TR: 2S0661
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, and when used, will disable the
internal speaker. An 8 ohm headset can be utilized as well.