TM  1-1520-240-10            3-2-9 e.  TOD. (1) TOD Receive/Update. NOTE The first TOD message received within one minute  of  selecting  T  on  the  hundreds  fre- quency   selector   switch   will   be   accepted. When  communications  are  slightly  garbled but  otherwise  acceptable  during  AJ  opera- tions, this is an indication of drift in TOD syn- chronization. A TOD update should be per- formed. (a) Frequency selector switches or channel selector switch — Set to predetermined TOD frequency. (b) Hundreds frequency selector switch — Momentarily select T, then release. A momentary 1667 Hz tone will be heard while receiving the TOD message. NOTE The following step is not necessary if TOD message  is  being  transmitted  continuously on the predetermined TOD frequency; for ex- ample,  continuous  TOD  message  is  being transmitted from a satellite. (c) Request TOD from another station with- in the net. (2) TOD Send. (a) Frequency selector switches or channel selector switch — Set to predetermined TOD frequency. (b) TONE  switch  —  Press.  A  momentary 1667 Hz tone will be heard, when the TOD message is transmitted, followed by a 1020 Hz tone until switch is released. (3) Emergency TOD Start-UP. NOTE The emergency TOD start-up provides an ar- bitrary  TOD  which  is  not  synchronized  to coordinated time. The radio set will not com- municate with any other Have Quick II radio set in AJ mode unless this new TOD is trans- mitted to other radio sets. (a) Perform step a MWOD Loading (b) Perform step b (1) Operate Mode (c) Hundreds frequency selector switch — Select T and hold while simultaneously pressing TONE switch. A 1667 Hz tone will be heard when the TOD is programmed. (d) TONE switch — Release. (e) Hundreds frequency selector switch — Release. f.  Anti-Jam Mode. (1) Perform paragraph 3-2-6 step Starting. (2) Load MWOD — Refer to paragraph 3-2-12 step a MWOD Loading. (3) Receive TOD — Refer to paragraph 3-2-12 step e(1) TOD Receive/Update. (4) Perform paragraph 3-2-12 step b(1) Oper- ate Mode. NOTE A steady 3125 Hz warning tone will be heard when the anti-jam (A) mode is selected and either  the  WOD  is  not  in  the  nonvolatile memory   or   the   TOD   has   not   been   pro- grammed. (5) Hundred frequency selectors switch — A. (6) Other frequency selector switches — Enter net number. 3-2-13.  VHF AM/FM Radio Sets (AN/ARC-186) a.  One or two VHF AM/FM radio sets (AN/ARC-186) are installed: No. 1 set on the pilot side of the console, No. 2 on the copilot side. Each set provides communications in the VHF AM and FM bands. The set operates in the following  modes  and  frequency  ranges:  AM  reception between  108.00  and  151.975  MHz,  AM  receiver  and transmit between 116.000 and 151.975 MHz , and FM transmit , receive, and homing from 30.000 to 87.975 MHz. Channel spacing is 25 kHz in all bands. Up to 20 channels plus two guard channels can be prestored in the  set  (removing  power  from  the  set  does  not  affect stored channels). When the set is used for FM homing and selected for display on the HSI by the HSI MODE SELECT panel, steering information will be shown by the course deviation indicator; homing signal strength will be shown by the glideslope deviation pointer: and homing signal adequacy warning will be shown by the glideslope failure and navigation failure warning flags. The set oper- ates on 28-volt DC power: No. 1 set receives power from the  DC  essential  bus  through  the  COMM  VHF  NO.  1 AM/FM circuit breaker in the No. 2 PDP; No. 2 set re- ceives power from the No. 1 DC bus through the COMM VHF NO. 2 AM/FM circuit breaker on the No. 1 PDP.. b.  Antenna   Select   System.  Three   antennas   are installed as part of the AM/FM radio installation: a top and bottom communications antenna and a FM homing an- tenna. Both AM and FM can be transmitted and received over the same antenna but not at the same time. Antenna selection is controlled by the two position VHF ANT SEL switch on the center instrument panel. The normal switch position is down at the SYS 2-SYS 1 position. The No. 1 AM/FM set is connected to the top antenna. If a water landing is to be made or the bottom antenna is damaged, setting the switch up to SYS 1-SYS 2 reverses the normal antenna connections and connects the NO. 1 AM/FM set to the top antenna and the No. 2 AM/FM set to the bottom antenna.  This  ensures  that  secure  voice  is  available through the top antenna. Power to operate the system is supplied by the DC essential bus through the VHF ANT SEL circuit breaker on the No. 2 PDP.