The GRC-206 Program Pacer Speak is a collection of radios used for
Forward Air Control. This rack holds the radios and related
equipment in a size that's compact and fits a HMMWV
or other military vehicles. I cut the pallet that it was
shipped on in half, leaving the center 2x4. This keeps it up
off the concrete floor and makes it a little higher for ease of
When the GRC-206 is mounted in the M998 HMMWV
it's called the MRC-144.
The system draws up to 1500 Watts at 24 VDC or 63 Amps. The
MEP-802 diesel gen set is only rated to supply 16 Amps from it's
NATO slave battery charging connector, but is rated for 5,000 Watts
on the 60 Hz AC output. The implication is that the M455-1 can convert the AC into 24 VDC to
power the system. The connector pins on the M455-1 are not as
large as the input connectors on the SB-4151 but many of them are
connected in parallel to carry high currents.
The first four versions were designed at the start. (V)1 and (V)3
have crypto and (V)2 and (V)4 do not have crypto. The
GRC-206 system specific boxes were designed to allow for optional
crypto and/or Have Quick operation.
Some speculation as of Dec 2008
? The URC-113A uses the RT-1444A which has ALE capability. But
the AM-7148 does not look like it can handle ALE, hence the need for
(V)3 systems were converted into (V)5 systems in Texas by replacing
the VRC-12 radio with SINCGARS radios and replacing the BITE/Audio
The manuals for (V)5 and (V)6 show the same BITE/Audio Interface box
and so far do not show how the remote can select the VHF-FM channel.
Upgrade Jul 27, 2009 RFQ
This would replace the HF power amp
with he Harris 150 Watt RF5800 amp and the 5328 Coupler. A
UHF SATCOM antenna is included in this RFQ so the Diplexer may be
related, but how with an HF radio?
Assemly, PA To Coup.Ct
Assembly PA/RF-382 Cplr.
CABLE (M17/74-RG-213) ASSY
CBL W TYP.N MALE CONN
CU001150W HF ANT. COUPLER
BASE 16 FT HF WHIP ANT
RF-5384VM-01HF ANT. COUPER
SHOCK MOUNT FOR RF-
ASSY, N TO BNC
ANTENNA MOUNT FOR SB-V
SERIES FEED THROUGH ADN
RF COAX SWITCH
CABLE, HARRIS RF-5800H-V001
Description from gaming web site
This description of
the varients might be wrong or incomplete GRC-206(V)1. Includes provisions for user-supplied
COMSEC devices. GRC-206(V)2. Does not include these provisions, but
space is available for other user-selected components. GRC-206(V)3. Is identical to the (V)1 except that
electronic counter-countermeasures (ECCM) are provided within the
UHF radio set. GRC-204(V)4. Combined with the Meteorological
Measuring System and ancillary equipment, this model is installed
in a HMMWV to form the TSQ-198 Tactical Terminal Control System
(TTCS) for the US Army. PSN-11 GPS capability is also
provided. GRC-206(V)5. Modifies the (V)3 to incorporate the
SINCGARS radio and the USC-43(V) Advanced Narrowband Digital Voice
Terminal (ANDVT). Built-In Test (BIT) functions were also
enhanced. GRC-206(V) P3I. As part of preplanned
product improvements, the GRC-203(V) can accommodate a PSC‑5
enhanced man-pack UHF transceiver, either as an addition or by
replacing an existing component (such as the RT-1319).
Improvements include UHF/FM SATCOM and DAMA, 8.3 kHz channel
spacing in VHF/AM for ICAO air traffic control in Europe, TDMA in
VHF/AM for US civil (Federal Aviation Administration) air traffic
control, SATURN ECCM in UHF/AM for NATO, expansion of the UHF band
to 512 MHz for civil command and control, and video compression
While reading FM 3-52.3
(learning about bedwindow gingerbread procedures) it mentiones
that the AN/TSQ-198 is a HMMWV mounted ATC system consisting of
VRC-83 - VHF AM low and UHF AM aircraft
VRC-90F - VHF low FM
(Ground version is the VRC-100) from FAS this is a
Nap-Of-The-Earth HF system:
The AN/ARC-220(V) and its ground
version, the AN/VRC-100(V) will replace the AN/ARC-199(V) and
AN/VRC-86(V) respectively. Secure communications will be
achieved through the use of the KY-100 Crypto Set. The
AN/ARC-220(V)1 consists of three line replaceable units; a
Receiver-Transmitter (RT), a Power Amplifier Coupler (PAC),
and Control Display Unit (CDU). The AN/ARC-220(V)2 is for
bussed (1553) aircraft and consists of just the RT and PAC.
The AN/VRC-100(V)1 consists of the three LRU's housed in a
metal casing along with a power supply and speaker. The
AN/VRC-100(V)2 is the AN/VRC-100(V)1 mounted on a HMMWV along
with associated brackets and antennas. The AN/VRC-100(V)3 is
for Echelons Above Corps and consists of the AN/VRC-100(V)1
with the AS-3791/G Broadband Antenna.
contract awarded for US Air Force
for retrofit/upgrade to (V)5 standard
for US Army TTCS program
transferred GRC-206(V) business to Hughes
into Raytheon Systems Company
US$25 million contract for Foreign Military Sale of
GRC‑206(V) to Greece
New Old Stock
This rack was New Old Stock. The packing bag label:
FSCM 37695 P/N 812084-803
1 EA EQPT MTG RACK
1 EA P/N B812132-801 FM BITE
1 EA P/N 5810-01-050-7184
1 EA P/N 5820-00-893-1323
VH-FM MOUNT (MT-1209/VRC)
The standard four foot square pallet gives some idea of size.
In the photo at left it can be seen that the MT-6250B rack comes
with all the equipment mounts and a lot of the system cabling.
Top Left VRC-83: 5 connectors
Top Center: O-1814: 2 connectors
Top Right: URC-113: 4 connectors
Middle Left: two KY-57: 3 connectors each
Middle Center: KY-65: 2 connectors
Middle Right: SDU: 6 Conn & PDU: 5 conn + rear input
Lower Left VRC-83: 5 conn
FM Bite/Audio Interface box: AS-1729, VHF-FM, SDU
third KY-57: 2 conn.
Lower Right: VHF-FM: 4 conn.
middle elevation left side is a box that connects to the back of the
Power Distribution Unit (PDU) and has vehicle DC power cables for
each of the system boxes.
37 7/8" wide x 16 1/8" deep x 30 3/8" hi.
There are two folding handles on the left side and two more on the
right side. I think that's for four men to each have a handle
if the rack was loaded, or a two man carry empty. The two man
empty carry is because of bulk more than weight.
The HF radio sits in the upper left corner of this back view.
There is a cable clamp on the back of the rack just below where the
AM-7148 power cable connects (just above the PDU location).
The box at the left center is behind the SB-4151 PDU and the cables
out the back are the DC power cables feeding most of the rack
equipment. The exception is the front panel cable to the RFO.
CAGE 37695 p/n 812805-801
SER NO. ____________________ (no serial number on blank
The brown paper is special anti-corrosion treated.
with C-11166 Universal
Remote System Control URSC
There are two rows of 0.36" wide mounting slots.
Three slots per row.
In each row the slots are 5.25" center to center
The rows are 4.00" center to center.
The bottom mount lip overlaps the battery cover and so you
need to remove
the remote in order to change the batteries.
The rectangular hole in the mounting plate clears the
passenger side dash mounted grab handle in the M151 Jeep.
System 9 Jan 2009
There are two Remotes, but only one
FO cable so the second one can not be connected.
The Power Supply is maintaining the Cyclon back up batteries
inside the RFO. The green lamp above the power switch is on
and the third lamp to it's left (under the cable) is Red
indicating SET CLOCK.
Two HYP-57 Wire Line Adapters are filling the KY-57 slots for the
Upper left has a couple of battery boxes from the HYP-57s, too
long to leave on.
KY-57 filling the slot for the VHF-FM radio.
SINCGARS VRC-87 sitting in the VHF-FM radio slot, but it will not
operate unless the MT-1029 is removed. But the AM-2060 with
a PRC-77 would fit the MT-1029 and you could connect the
BITE/Audio Interface and the audio so the remote would work with
it. Although there is only one channel.
The M455-1 is just sitting at the lower left corner. It's a
little shorter than the RT-1319.
The FM Bite box marking AS-1729
suggests that this rack was designed to hold a VRC-12 series radio
instead of a SINCGARS radio.
Also the mount in the lower right corner looks like the MT-1029 which would hold a VRC-12 series receiver like the
RT-524 w/speaker or RT-246 with 10 remote controled
channels. There is no J-3513 in the MT-1029 like in normal
VRC-12 series radios with the KY-57 so it's function must be done
in the BITE/Audio Interface.
It's looking like the RT-246 that has 10 channels that can be
selected remotely is what went into this rack. That means
that the SDU and/or BITE/Audio Interface contain circuitry that
allows serial control (since it must be done over the fiber optic
link) of the channel. This serial protocol may match the
SINCGARS serial channel selection protocol?
Why the BITE/Audio Interface has the VHF-FM antenna connection is
also a mystery.
to/from AS-1729 Antenna
cable to SDU and REMOTE on radio
& (ReTrans or Audio) on rradio
In a crypto system the handset is
connected to the KY-57 and so the PTT for the radio comes from the
KY-57, through the BAI box then to the radio.
When no crypto the VHF-FM audio cable from the SDU is connected to
the Retransmission connector on the radio.
There is no connection to the radio AUDIO connector in the system.
The RT-246 or RT-524 has the internal crypto switch left in the
plain text position for both unsecured and secured
coms. When the BAI box is connected to the radio
it makes the same connection that the internal switch would have
made. That way it's easy to unplug the BITE box to get back
to plain text transmissions without opening up the radio.
in from Rx
The BAI replaces the J-3513 and by sampling the RF during Tx
generates a bit of BITE.
System versions (V)1 through (V)4
were powered by the MEP-025A 1.5 kw gas DC generator. It
weighs 121 pounds dry.
Later versions use the MEP-802A
5 kw 60 Hz AC diesel generator skid mounted tatical quiet It
weight 800 pounds dry. Since the DC output from this
generator intended for battery charging can not supply enough
current for the GRC-206 system an inverter is needed. The M455-1 accepts either DC or AC inputs and
provides 28 VDC output as one of it's outputs. But the
connector contacts look too small for the 50 Amps needed by the
GRC-206. So it's not clear how the MEP-802A can power the
System versions (V)1 through (V)4
were intended for mounting on either the M151
Jeep, M113 Armored Personel Carrier.
The MT-6250 is 38" wide at the bottom 9excluding the ears at the
top) and just fits between the rear wheel wells in the M151 Jeep.
The Remote Mount bracket is designed to go
over the passenger dash mounted grab handle.
The Generator and it's fuel tank would be on the 1/4 Ton M-416
This appears to be a custom rack(not the MT-6250) and uses radios
made in Israel.
GRC-206 in M151 view of Remote Control
Photos courtesy of Chance Wolf
HF Whip Antenna
AM-2411TG RF Amp
FO Cable spool
AM-2411TG RF Amp
AM-1760 or AM-4760 RF Amp
(passenger side dash over grab handle
Later systems are typically mounted on the M998 HMMWV.
The main input connectors has a 24-22 Insert and pins that are
The cap is marked 8544 Cannon CA121003-908.
Pin A is +24 Volts and pins B & C are ground. Maybe pin D
is also hot? That way the two top pins would be hot and the bottom
When 30 volts is applied to A and D the RFO receives power no matter
how the SB-4151 switches are set. Notice that J3 is not in the
box with the lower switch, J1 & J2, i.e. it's hot all the time.
But the green power light does not turn on when the mode switch is
at M-G or Vehicle, but only in Vehicle Override as shown at left.
The power connector on the back of the AM-7148 is only hot when in
the Vehicle Override position.
The input voltage in the photo is 29.8 yet the voltmeter on the PDU
is reading about 20. When the mode is switched from Vehicle
Override to Vehicle the green lamp slowly (maybe 5 seconds) dies out
like there was a big capacitor discharging.
Maybe this PDU is
The row of aux pwr banana jacks are switched on or off independent
of the Master reset switch.
Jacks J1 & J2 switch on or off independent of the master power
The current on the power supply is caused by charging the batteries
in the RFO.
The RT-1444 is not yet installed so the remote control cable is
laying in front of the AM-7148. The RT-1209 is
installed. But when the mode switch is set to STATUS or MODULE
TEST nothing happens, as if it was not getting any power.
Both the PWR and FO cables are connected, and there's one internal
battery, but when the BATTERY switch is turned ON the red lamp comes
on, the fault tone is heard and the status display shows Cable
Fault. It's as if it was not working.
After opening up the SB-4151 it was
discovered that J4 the Vehicle input jack MUST have pin D grounded
in order for the contactor in the SB-4151 to actuate turning on
Once that's done then the AM-7148 does the module test and the
Remote no longer shows the cable fault error. Also the
remote allows keyboard entries, like setting a frequency, but
since there's no radios now connected gives an error beep when you
try to enter the frequency.
The RT-1319 is in the upper left UHF
AM military air band position. But the RF amp is still
The RT-246 is in the lower right VHF FM military ground and air
All three KY-57 slots have been filled, but need to add internal
jumpers to pass clear text.
The M455-1 needs some unknown front panel jumper or wiring to get
it to turn on.
Have a linear power supply that should be able to power one radio
and cable with plug to fit SB-4151.
ME-548/GSM-317 Fiber Optic Power Meter (Not
I bought this in the hope that it would work with the dual
fiber optic cables in the GRC-206, but the dual fiber optic
connector is larger than for the GRC-206 and is for the GSM-317
Test Set. The other part of the test set is the
T-1514/GSM-317 Optical Transmitter. (see: TM
2000-OD/2C) But here's some photographs of it.
Shown with GRC-206 remote FO cable
One or both of the center FO receiver ICs
Signal Distribution Unit SDU SB-4151 Power Distribution Unit
PDU O-1814 Reference Frequency Oscillator
RFO PRC-104 Manpack HF radio AM-7148 HF RF Amp RT-246 VHF FM Radio RT-1319 VHF AM Aircraft Radio RT-1444 Remote Control adapter for
the RT-1209 (PRC-104) KY-57 Transmission Security Device for
VHF and UHF radios KY-65 Narrowband Secure Voice Unit for HF
radios GRC-206 Cables
VRC-83 Vehicle version of PRC-113 with RF Amp Aircraft radio
covering VHF-AM and UHF-AM bands
There are three versions of the
RT-1319, the first did not use "Have Quick", the second used the
first version of Have Quick and the third used Have Quick II.
The RFO is in this system specifically to supply the RT-1319
with TOD for Have Quick, so this system uses either of the Have
Quick versions of the radio.
PP-1104 AC power supply
@ 24 Amps (NOTE: Exceeds
normal household 15A circuit capacity)
230 @ 12 Amps
60 Hz AC
Output: "12 Volt" 11.5 to
17.5 VDC (100 Amps @ 14 VDC)
"24 Volt" 23 to
35 VDC ( 50 Amps @ 28 VDC) PP-6224 only 30 Amps at up to 30
Volts, maybe enough to run one radio and the rest of the system. J-4024/U GRC-206 Interconnecting Box -
Allows connecting a DLED ((Dedicated Loop Encryption Device) to
either of 2 transmitters and either of 2 receivers and TTY
PSC-2 Digital Communications Terminal (DCT) provides burst
Model 1040 ALE Modem - RT-1444A - ALE version of remote adapter RT-1444. Used in the
GRC-206(V), URC-113A. Only provides ALE when used with the
GRC-206(V), not front panel ALE.
A Close Call
- "Airmen like Senior Airman Courtney Hinson, a terminal attack
controller, are entrusted with an MRC-144 weapons system — a
half-million dollars in communications equipment housed within a
Humvee. As part of the 18th Air Support Operations Group, supporting
18th Airborne Corps, Hinson and his comrades are responsible for
keeping their systems and the mission running. And testing
frequencies is part of knowing the system."