THE PRC-25 AND PRC-77 ARE WIDEBAND FM VHF PACKSETS THAT OPERATE IN THE 30 - 76 MHZ RANGE. THEY TRANSMIT 2 WATTS OUTPUT POWER WITH A TRANSMIT DEVIATION AROUND 15 KHZ. BY TODAY'S STANDARDS, WHEN THINGS ARE CHANGING TO ULTRA-NARROWBAND FM (12.5 KHZ CHANNELS) THE PRC-25 AND PRC-77 ARE VERY WIDE USING A 50 KHZ WIDE CHANNEL. (IT IS PROBABLY REALLY MORE LIKE 60 OR 75KHZ WIDE, BUT WHO IS COUNTING WHEN IT GETS THIS WIDE. IN ANY EVENT, THE CHANNEL STEPS ON THE SELECTOR KNOB ARE EVERY 50 KHZ.)
THE PRC-25 WAS DEVELOPED IN THE VIETNAM ERA AS A REPLACEMENT FOR THE PRC-8/9/10 SERIES OF RADIOS. THE PRC-25 WAS A VAST IMPROVEMENT USING CHANNELIZED STEPS PRODUCED FROM IT'S FREQUENCY SYNTHESIZER. IT ALSO WAS THE FIRST RADIO TO USE A TONE SQUELCH CIRCUIT (150 HZ) RELIEVING THE OPERATOR FROM HAVING TO DEAL WITH THE SQUELCH CONTROL SETTING.
THE PRC-25 IS ALL SOLID STATE WITH THE EXCEPTION OF THE 2DF4 FINAL OUTPUT TUBE.
THE PRC-77 IS A VERY CLOSE COUSIN OF THE PRC-25, AND WAS DEVELOPED TOWARDS THE END OF THE VIETNAM WAR. IT HAS IDENTICAL OPERATING SPECIFICATIONS, AND IT'S OUTSIDE CONTROLS AND APPEARANCE ARE IDENTICAL. INSIDE, IT HAS AN UPDATED SYNTHESIZER CIRCUIT, AN ALL SOLID-STATE TRANSMITTER, AND A FEW OTHER CIRCUIT UPDATES. BEING 100% SOLID-STATE, IT HAD BETTER BATTERY LIFE.
MOST BATTERIES ARE IDENTICAL BETWEEN THE TWO SETS, AND MOST BATTERIES ARE COMPATIBLE WITH BOTH RADIOS AS THEY CONTINUED TO PROVIDE THE 3 VOLT DC FILAMENT TAP FOR THE FINAL OUTPUT TUBE AFTER THE PRC-77 WAS DEVELOPED. AMAZINGLY, THERE ARE STILL PLENTY OF MAGNESIUM BATTERIES WITH LONG SHELF LIVES STILL AVAILABLE FOR THESE RADIOS AS OF THIS WRITING. IN ADDITION, AFTER MARKET D-CELL ADAPTERS ARE AVAILABLE FROM PRC68.COM, AND YOU CAN MAKE YOURSELF A DANDY RECHARGABLE BATTERY PACK FROM AN OLD DEAD MAGNESIUM BATTERY BACK AND SOME NIMH C-CELLS. (IF YOU PLAN ON USING YOUR HOME MADE BATTERY FOR A PRC-25, DON'T FORGET TO INCLUDE A 1-OHM 5 WATT RESISTOR ON THE 3V FILAMENT TAP TO TAKE IT EASY ON THE OLD GIRL WHEN YOU KEY UP THE FILAMENT COLD.)
USEFUL LINKS:
N3OC'S LIST OF PRC-25 & PRC-77 FAILURES AND REPAIR TIPS (revised 5/28/2013)
MOST HAMS USING THESE RADIOS USE THEM EXCLUSIVELY ON 51.0 MHZ, WHICH SEEMS TO BE A GOOD SPOT TO AVOID INTERFERING WITH OTHER NARROWBAND USERS OF THE BAND. YOUR MILEAGE MAY VARY. BE A GOOD NEIGHBOR WHEN USING THESE RADIOS ON THE AIR AND MAKE SURE YOU ARE NOT ON A LOCAL REPEATER OUTPUT OR INPUT!
JOIN US ON THE AIR EVERY YEAR AT DAYTON ON 51.0 MHZ ON THE COLD WAR NET AT 2PM SATURDAY.
LAST UPDATED
05/29/2013