Editing AN/PRC-77 Portable Transceiver (section)

== History ==
The AN/PRC-77 entered service in 1968 during the [[Vietnam War]] as an upgrade to the earlier '''AN/PRC-25'''. It differs from its predecessor mainly in that the PRC-77's final power amplifier stage is made with a transistor, eliminating the only vacuum tube in the PRC-25, as well as the DC-DC voltage converter used to create the high plate voltage for the tube from the 15 V battery. In addition, the PRC-25 could not support [[Secure voice|voice encryption]] devices, but PRC-77 transmitter audio bandwidth was widened to give it the ability to use the TSEC/KY-38 [[NESTOR (encryption)|NESTOR]] voice encryption system used in Vietnam, and the later KY-57 [[VINSON]] family. Problems were encountered in Vietnam with the combination as described in the NESTOR article. The transmitter's spurious emissions were cleaned up to create less interference to nearby receivers. The receiver's performance was also hardened in the PRC-77 to enable it to better reject interference suffered from nearby transmitters, a common operating set up that reduced the effectiveness of the PRC-25.<ref>Military Communications A Test for Technology CMH_Pub_91-12-B, pg 201 and Army procurement decision B-161031, JUN. 1, 1967</ref>  The receiver audio bandwidth was also increased to operate with the encryption equipment.<ref>B-161031, JUN. 1, 1967</ref>

There were no changes to the external controls or looks, so the two radios looked and the operating controls were the same. The equipment tag glued to the edge of the front panel was the main (external) way to tell the difference.  The original batteries had a 3 V tap (series diode-reduced to 2.4 V) for the PRC-25's tube filament. This remained unchanged so the batteries could operate either radio it was placed in, but the PRC-77 did not use the 3 V tap at all.  With the more efficient all-transistorized circuitry, and without the DC-DC step-up voltage converter for the tube, the common battery lasted longer in the PRC-77 under the same conditions.  "OF THE TWENTY-FIVE (25) ELECTRONIC MODULES ORIGINALLY USED IN BOTH THE TRANSMITTER AND RECEIVER PORTIONS OF THE AN/PRC-25, ONLY EIGHT (8) OF THE MODULES USED IN THE AN/PRC-77 ARE INTERCHANGEABLE WITH THE AN/PRC-25.'"<ref>B-161031, JUN. 1, 1967 https://www.gao.gov/products/b-161031</ref>

Today the AN/PRC-77 has largely been replaced by [[SINCGARS]] radios, but it is still capable of inter-operating with most VHF FM radios used by U.S. and allied ground forces.<ref name="olive-drab.com">http://www.olive-drab.com/od_electronics_anprc25.php AN/PRC-25 and AN/PRC-77, Olive-drab.com</ref> It was commonly nicknamed the "prick-77" by U.S. military forces.<ref name="Dickson2011">{{cite book|first=Paul|last=Dickson|title=War Slang: American Fighting Words & Phrases Since the Civil War|url=https://books.google.com/books?id=ixTBwQWX7F8C&pg=PA425|year=2011|publisher=Dover Publications|isbn=978-0-486-47750-3|pages=425–}}</ref>