TM  1-1520-240-10            3-2-3 CONTROLS/ INDICATOR FUNCTION Off Released position disables mi- crophone. Talk Depressed position: enables headset microphone. Hoist Control PTT Switch (on hoist control grip) Posi- tion Two position PTT Switch. Off Released position; disables mi- crophone. Talk Depressed position; enables headset microphone HOT MIKE switch on HOIST OPERA- TORS PANEl (Chapter 4) Three position toggle switch selects hoist operator’s inter- phone operating mode. OFF Requires operation of PTT switch for interphone commu- nications. HOT MIKE Operation of PTT switch not required for interphone com- munications. MOM ON Operation of PTT switch re- quired for interphone commu- nications. (Spring loaded to OFF position when released.) Gunner’s Foot Switch Position Two position pressure sensi- tive switch mounted in move- able floor mat. Off Released position; disables mi- crophone. On Depressed position; enables microphone. Figure  3-2-2.  Interphone Control (C-6533/ARC) 3-2-3.  Antenna System. Antennas used for avionics communications and elec- tronic systems equipment are shown in figure 3-2-3. This figure  shows  the  maximum  antenna  configuration.  All antennas illustrated may not appear on all helicopters. 3-2-4.  UHF-AM Have Quick II Radio (AN/ARC-164). The UHF Have Quick II (HQ II) radio (AN/ARC-164) is located on the center console. It is capable of providing normal and ECCM, Anti-Jam (AJ) two-way voice com- munications in the band from 225.000 to 399.975 MHz in 25 kHz increments. The HQ II is capable of operating with the Basic HAVE QUICK radio. It also provides 20 preset frequencies and will monitor and transmit on a perma- nent  guard  channel  (243.000  MHz).  When  in  the  AJ mode preset 20 is restricted to AJ operations. The usual operating  mode  for  the  radio  set  is  the  normal  mode where the radio uses 1 of 7,000 frequencies. Power for the UHF-AM Have Quick II radio set is supplied by the 28 volt essential bus through the COMM UHF AM circuit breaker on the No. 1 PDP. There are presently three configurations of the AN/ARC 164-UHF/AM  radio.  The  following  paragraphs  identify the visual differences in their configurations. a.  AN/ARC-164,  UHF/AM  Basic  (not  modified  for Have Quick) 100MHz selector for the hundreds digit only has a 2 and a 3 position. b.  AN/ARC-164 UHF/AM Have Quick I (capable of single WOD entry only). Has a four position selector for the hundreds digit, A, 2. 3, and T. Does not have EMB label adjacent to the Pre-set channel selector. c.  AN/ARC-164 UHF/AM Have Quick II. Same as b. above, but includes EMB label adjacent to the Pre-set channel selector. Reverse compatible communications between HQ II and HQ I radios in the AJ mode, is accomplished by either, entering  a  single  WOD  or  selecting  the  appropriate MWOD and net number with a suffix 00. 3-2-5.  Anti-Jam Mode. The  AJ  mode  uses  a  frequency  hopping  scheme  to change  the  frequency  many  times  per  second.  this makes it difficult for the enemy to jam the frequencies since knowledge of the frequencies being used by the pilot are unavailable. Because the particular frequency used at any instant depends on the precise time-of-day (TOD),  all  participating  UHF-AM  Have  Quick  II  radios must have clocks which are synchronized. In addition, all participating  radios  must  have  the  same  word-of-day (WOD) and net number data when in the AJ mode.