Icom IC-21 Instructions Manual page 3

SECTION II — DESCRIPTION
receiver.
The transmitter section will produce a minimum of 10 Watts RF out. Again, a Zener regulated
crystal oscillator is employed for initial frequency stability. Twenty-four crystal controlled
channels are provided for operating convenience and versatility. High-Q LC coupling and
shielded stages provide minimum interstage spurious reaction. An encased low-pass filter is
placed at the output to further insure undesirable frequency products not being emitted. An
ingenious final PA transistor protection device (APC) is incorporated in the final output
circuitry. A tiny VSWR bridge and four DC amplifiers constantly monitor the output for high
VSWR, a shorted or absent antenna load, or other difficulty that would cause irreparable final
transistor damage. Should these difficulties occur, the APC instantaneously disables the driver
and final PA, without damage. A two-way power supply, AC or DC, is built in.
All circuitry is constructed in a series of modules which are easily removable for servicing. The
modules are housed in a sturdy, anodized brass frame, which is in turn, housed in a rigid metal
chassis, providing for an extremely durable and rugged unit. Premium care has been taken to
filter and regulate internal DC voltages. A DC input filter is provided to eliminate alternator or
generator "whine" generated in the vehicle. Power line inputs are voltage regulated
to smooth out power fluctuations to within + 10%. Test points are brought up from all major
circuits to facilitate maintenance checks and trouble shooting, should the need arise.
Each unit comes with built-in speaker, a high-quality dynamic microphone, microphone clip, AC
and DC cables, external speaker plug, and operating manual. An optional mobile mounting
bracket is available.
A modern styled face plate, easy-to-read meters, and convenient controls, with design that will
compliment your ham shack or auto. A welcome addition to any fixed station or dashboard.
SECTION ІН — INSTALLATION
1. Unpacking:
Carefully remove your transceiver from the packing carton. It is recommended you keep