Upgrading the PRC-127 for Fire Service
Many fire departments and firefighters have contacted me about the use of PRC-127's for fire duty. While the radio is perfectly suitable for local department use on frequencies below 160 MHz, the radio would need to be upgraded if it is to be used in conjuntion with other agencies on wildland fires, particularly the Bureau of Land Management and the United States Forestry Service. The reason is BLM and USFS routinely assign a wide range of frequencies when coordinating a large wildland fire mission. In addition, the frequency upgrade will allow coordination with both RACES civilian groups operating in the 2 meter band with governmental agencies operating in the 148-174 MHz band.
To upgrade the PRC-127 for operation from 145-173 MHz requires both hardware and software modification. First, the ferrite slug in the VCO coil on the transmitter/synthesizer board needs to be changed with an equivalent brass slug to raise the operating frequency. Second, the four option codes need to be changed to 00D0, 3927, EC60 and 195F using an LAA-0725 RS-232 cable and the LMR.EXE program. To complete the upgrade requires realignment of the receiver for maximum performance over the higher frequency range.
The finished upgrade will allow operation from 145-173 MHz with good performance and from 173-174 MHz with slight receiver degradation. The transmitter will produce 2 Watts at 148 MHz, trailing down to around 1 Watt at 173 MHz. I perform this modification routinely to existing radios radios for $75.00 each plus shipping. Be advised that this price does not include any repair work which may be necessary before upgrade.