VHF/UHF Ham Radio
Transmit
Limitations
John 'Miklor' K3NXU
Jim Unroe KC9HI
October 2021
Transmitter
Limitations
Up until recently, most ham radio transceivers had the
capability of operating in the frequency range of 136-174MHz and
400-520MHz.
The majority of these radios have not been certified for use
in the FCC part 80 (Stations in the Maritime Services), part 90 (Private Land Mobile Radio Services),
part 95 (FRS, GMRS and MURS) radio services. Transmitting on frequencies assigned to those services
has always been contrary to FCC rules governing those services.
Because it has been so easy to set up these radios to operate on the frequencies of these services,
many owners programmed these radios to operate on these frequencies anyway.
The FCC has finally pressured the manufacturers and vendors of these radios to follow the rules and they have responded by preventing their uncertified radios from being able transmit on
frequencies that require equipment certification.
What's Different
New amateur ham radio transceivers entering the US are now restricted to transmitting on ham frequencies only.
144-148MHz and 420-450MHz.
Although you may be able to program GMRS, FRS, MURS, etc. on the receive side,
the transmitters are now restricted. This may result in an audible tone
when keying the transmitter or message appearing on the LCD display.
Firmware / Software
***
This cannot be altered with software. The internal firmware on many of these radios is OTP (one time programmable)
from the factory, so there is no update to change this.
The same software used to program the older models will still work with
the newer versions, the only difference is the newer transmitters will
not respond to the out of the ham band frequencies.
One a Positive Note
Some models have now improved/narrowed their internal filtering on the transmit side. This reduces spurious
emissions previously found on several models.
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