RT-1439 SINCGARS

In my opinion,

older DF sets that use a conventional receiver channel will have trouble DFing a frequency hopping radio, but DF sets that use what amounts to a spectrum analyzer can DF a frequency hopping radio, and probably can de-interleave a number of them, so the anti DF part of the reason for frequency hopping is not too strong.  Note that SINCGARS uses about 100 hops per second, which is considered a slow hop.  It is not a direct sequence spread spectrum system like is used by GPS. 

Once a FH radio has been located by DFing then it's possible to jam it.   Not by knowing the hop sequence, but by listening for each new transmission (like using a very fast spectrum analyzer) and then jamming that transmission, then the next, and so on.  So the advantage of Frequency Hopping against a sophisticated enemy has a short life.  The next generation radios will probably be either fast hoppers or direct sequence spread spectrum types.

GPS is designed so that all the satellites transmit in the same frequency band and the receivers separate them by using different pseudo random codes that are designed to all be mutually orthogonal.  Meaning that they have minimal interference with each other (minimal cross correlation).  The SINCGARS radios don't have that capability and so when a number of them are co-located there are times when two nets will use the same frequency at the same time causing a collision.  This can become a problem.  Note that if the hopping bandwidth is narrowed the anti jam resistance is lowered in direct proportion to the bandwidth reduction, so that's not a good thing to do.  It's more probable that interleaved hop sets are used.

Although it's theoretically possible to have an analog voice signal on top of a slow hopping carrier it's not as good as using a digitized voice (or data) signal on top of the slow hopper.  This way there can be some overlapping and redundancy in the digital data, similar to what's done on a music CD that can tolerate a small scratch.  In the SINCGARS it's called forward error correction.

The ECCM module works in two ways.  One relates to choosing which RF frequency is to be used and the other related to converting from analog voice to digital and back from digital to analog.

The RT-1439 has a channel scan function.  That's to say that it can be made to scan each of the programmed SC channels.  It can not do a frequency scan like is done with scanner radios where there's a start and stop frequency and a channel spacing.  For more on this and the half dozen or so options see TM 11-5820-890-10-3 Chapter 4 Other Operating Procedures, Section V Additional Operating Procedures, Scanning. (page 4-24 in the no change version).

Preparation

Before running the self test the Antenna and Hand set should be removed. (PS Mag March 2001 issue 580 pg 46) either one may cause signals to be present that the self test does not allow for. (Might cause a FAIL 1)

The Data Rate knob should be set to OFF. (some positions will cause a FAIL 2).  This happened when I first got the radio and now after using it this no longer happens.  Not sure what's going on.

Whenever the Function (FCTN) switch is put into the TST position the radio performs a self test.  This includes not only the internal systems but also stimulates and reads test results on externally connected equipment.  If the test passes the display will show GOOd otherwise one or more FAIL # messages will appear.

Results

Diagnostic

If a FAIL-Number message appears and the FCTN switch is moved to any other position and any keyboard button is held down while turning the FCTN switch back to TST a new self test is started, but now instead of a FAIL-# message the message is a preamble number some dashes and a detail number.  For example the Normal Self Test shows FAIL 2 and the Diagnostic test shows 2--01.

TM 11-5820-890-30-5 Chapter 2 has some information on how to interpret the self test results, but seems to be missing the diagnostic 2--nn  and higher number messages.  If you have that manual please let me know.  In general all the 890 series manuals are very poor regarding explaining what the FAIL # messages mean, especially ones where the operator could correct the failure.

Using the front panel RF switch allows adjusting the Man Pack RF output power to LO, M or HI (the PA switch position only works when an external RF Power Amplifier is connected).  Using the 1 meter whip antenna on the radio and an outdoor OE-254 feeding the HP 4395A Spectrum Analyzer input the output signal (dBm) was measured.

Freq MHz	LO 0.5 mw	M 160 mw	HI 4W
30	-65	-39	-26
40	-69	-45	-32
51	-58	-32	-21
60	-74	-47	-34
70	-67	-43	-32
80	-62	-36	-23

There appears to be about a 20 dB change between LO and M and a 10 dB change between M and HI, an overall change of 1,000 times in power.  This is the same amount of change that occurs between using a 1 meter whip and a rubber duck antenna on a PRC-68 series radio.

The signal is not a single carrier when no audio input is fed to the mike since the radio is sending a 150 Hz tone.  Deviation is about 7.5 kHz without any audio input.  The channel frequency is right on at 51 MHz.

The current draw for the "HI" power position is more than 3 Amps (it trips the over current limit on the BK Precision 1786 P.S.).

The LED SIG and frequency displays turn off after a short time to conserve battery power, but then the radio is dark and it's easy to leave it turned on thus draining the battery.  It might be better if one of the LEDs were to flash every so often to remind you that the radio is powered and that the main battery is OK.  The LED to flash is the battery gauge reading on the SIG display.

When Powered from a Vehicular mount the display time out is disabled and the display stays lit.  Brightness can be controlled by the DIM knob.

The RT-1439 requires a 150 Hz tone with about 7.5 kHz deviation to open the squelch

FCTN = LD-V  Load the Transmission Security Key Variable
Mode = FH
Connect fill device, select T1 or T2, power on
Connect Fill cable, note display shows FILLE
Press "0 H*Ld", note display shows LOAD
If there's a problem the display shows bad, or if the fill was OK the display shows GOOd

FCTN = LD Load either a Hop Set or Lockout Set
Mode = FH
Connect fill device, select 1 through 13, power on
Connect Fill cable, note display shows FILLE
Press "0 H*Ld", note display shows LOAD
If there's a problem the display shows bad, or if the fill was OK the display shows GOOd

Manual Set Time & Date Set
FCTN = LD
Press "TIME" and enter the Julian day number (1 to 99) based on the table in the back of the manual (note there are two tables, one for normal years and another for leap years), press "Sto Ent", enter the 2 hours digits, press "Sto Ent",  (This last press sets the seconds to 00).
1 Jan is always 01, 28 Feb is always 59, Feb 29 is 60, 1 March is 60 in a regular year and is 61 in a leap year, and all the rest of the days follow.   27 Oct in a regular year is day 00, and in a leap day 00 is Oct 26.

PLGR AN/PSN-11 GPS Time & Date Set
TM 11-5820-890-10-7 which includes the PRC-119A (RT-1523) has a Task 3 "Load PLGR Data and Zulu Time into SINCGARS RT".  There's no mention that the RT-1439 does not support this fill, but when I try, it does not work.  (error in PLGR says radio not responding).
FM 11-1 says PLGR only works with RT-1523A and higher letter radios and the ARC-201A.  MX-10579 can only load FH data into the RT-1439 and the ARC-201 (not any of the RT-1523 series radios and not the ARC-201A).

TM 11-5820-890-10-3 which applies to the PRC-119(no letter), i.e. to the RT-1439, describes how the NCS is to either manually set the time and date or use Electronic Remote Fill from another network, no mention of using a PLGR.

This procedure worked on the RT-1523C to load date and time from PLGR:

Set the radio to SC and set to CT.  
Select SINCGARS under the MENU key of the PLGR, select ACTIVATE on the PLGR,
then LOAD on the RADIO.  
LOAD displays on the radio, and PLGR displays SUCCESSFUL TIME FILL.  
Sure enough had the correct julian day on the radio and UTC time.

The 5 digit LED display is of the 7-segment type which can display the digits 0 - 9 as well as some stick type letters.

Frequency

As the CHAN switch is moved from MAN through 1 - 6 to CUE in SC mode (FCTN any pos)  if there are no frequencies loaded the display will show:  30000 (default MAN freq), FILL 1 through FILL 6 and FILL 7.  But if the HRCRD is used to scan those same channels the display will show FILLE on all but the CUE channel which shows FILL 7. 

Below the display between the second and third digit from the left is printed a decimal point that separates the MHz part of a single channel frequency from the lessor digits.  The smallest frequency step is 5 kHz, so you can load 30.125, but not 30.123.  The SINCGARS are much more restricted than the PRC-126 in that the offset between Tx and Rx frequencies is limited to +/- 5 or 10 kHz in the SINCGARS but the PRC-126 has no restrictions.  This limits the flexibility of how the radio is used, for example with the PRC-126 you could program the Tx frequency to be the input to a repeater and the Rx frequency to the the repeater output.

TSK

If the Transmission Security Key has been loaded but neither a hop set nor a lockout set has been loaded the display will show cold.

Hop Set

As the CHAN switch is moved from MAN through 1-6 to CUE in FH mode (FCTN any pos)  if there are no hop sets loaded the display will show:  FILLE on all channels.  If there's a Hop Set loaded the display will show Fnnn (Hop Frequency net ID number nnn).  If the Lockout set has been loaded but the hop set has not yet been loaded the display will show HLncc.

With a Hop Set loaded the display will show Fncc where the first letter is always F the second letter is the hop set ID and the cc is the net ID between 0 and 99.  The set starting time can be changed by the NCS when in FH-M mode.

Just after a hop set is loaded the display shows HFncc if the set was a Hop Set or HLncc if it was a Lockout set.

Z-A

A few seconds after switching to Zero-All the display shows good.  Meaning that all memories have been erased.  Note you need to go through this switch position to get to STW on the RT-1439 (OFF on the RT-1523x) where power including backup battery is disconnected.

Cue allows a radio that is not part of a FH net to get the attention of the NCS when the net is idle even through the NCS is in a FH net.  This probably works like a police scanner priority channel, i.e. the radio checks the Cue frequency when in FH or FH-M mode and when the channel is idle.

The NCS (and alternate NCS) would hear any SC radio sending on the Cue frequency.  Another feature of Cue is that if the channel is changed to Cue, then to MAN and back to the net channel, it can passively rejoin the net probably without the wait associated with a passive net entry.

I think that only one station in a net may be set in FH-M mode.  This is because the Master station is sending the net time to keep all the net stations in time sync.  If two stations tried to do this the times would not match and there would be a problem.  The alternate NCS would switch into FH-M mode if something happened to the NCS.  If this is the case then all the stations in a net (with that Cue frequency set into their radios) would be aware that a Cue call was in progress, but typically only the alternate NCS would switch to the Cue channel and talk to the calling station, which might be a VRC-12 Series or PRC-77 radio.

The instructions for how to make a CUE call are very consistent in that the calling station needs to turn off voice encryption. and just press PTT (no voice call is being made).  Since the calling station does not know when the net is idle the process may need to be repeated several times until an idle time is used for the call.  The SINCGARS radio probably detects that there's a carrier on the CUE frequency and alerts the radio operator.

Note that although a SINCGARS radio can store 6 separate channels (6 nets) there is only one CUE frequency CHAN position and so the CUE frequency needs to be manually programmed for each of the 6 channels as does the MAN frequency.

TM 11-5820-890-20P-1 Figure 1 (23 pages) has drawings of the components of each of the PRC and VRC configurations including the RT-1439, RT-1523A and RT-1523D radios and the correct letter versions of the related equipment.  The 20P-2 manual covers the RT-1523E. 

There are a number of letter suffixes to the nomenclature like PRC-119/A/B/C/D/E where the system letter is the same as the RT suffix letter.  The Power Supply/Adapter (aka VAA) also changes to be compatible with the radio.

The early SINCGARS radios were developed by ITT Aerospace/Communications Division (31550) around 1988 and second sourced to General Dynamics Land Systems (0HGX3).
 The radio version progression has been:
RT-1439 - Non ICOM  made by ITT (31550) needs external KY-57 RT-1523 - Internal ICOM ( KY-57 built in) increased the run time from 16 to 25 hours per battery.  probably made by ITT
                   TM 11-5820-890-10-8 Fig 2-2 RT-1523 Features
                   TM 11-5820-890-30-4 Chapter 2

RT-1523A- Internal ICOM ( KY-57 built in) increased the run time from 16 to 25 hours per battery. TM 11-5820-890-20P-1 Figure 203, 204
       made by GD Land Systems (0HGX3)
                   TM 11-5820-890-10-8 Fig 2-3 RT-1523A Features

RT-1523B  TM 11-5820-890-20P-1 Figure 166 Not much mention in the TMs, so maybe made by GDLS
                TM 11-5820-890-10-8 Fig 2-4 RT-1523B Features

RT-1523C/D - Special Improvement Program (SIP) adds more data modes including RS-232 and IP packets to support easy computer interfacing for the Tactical Internet.  Also an interface to an external GPS receiver to allow automatic position reporting. This requires an additional connector on the Vehicle Power Supply/Adapters.  see FM 6-02.72 Tactical Radios
1523C = TM 11-5820-890-20P-1 Figure 166 probably made by GDLS
               TM 11-5820-890-10-8 Fig 2-5 RT-1523C Features

1523D = TM 11-5820-890-20P-1 Figure  205 internal layout very similar to the RT-1439 so probably made by ITT.
               TM 11-5820-890-10-8 Fig 2-6 RT-1523D Features

RT-1523E - half size Advanced Special Improvement Program (ASIP) also a single radio can act as a packet repeater (sort of a digital version of a simplex repeater). Uses DSP technology that can be upgraded. The tactical communication system (TCS) handset replaces the HRCRD that displays the operators Lon-Lat and the received stations Lon-Lat.  The radio really is a dual channel radio with both voice and digital coms at the same time.  Really a new radio. The GPS key controls how the radio transmits GPS data. GPS is set to OFF, voice only (AUTO), periodic (PER), or movement (MOV), and can only be modified in CT. Periodic and movement modes automatically generate short GPS-data-only transmissions.
RT-1523E and Radio sets that use it = TM 11-5820-890-20P-2  all ASIP made by ITT.
RT-1523E(C)/U  NSN 5820 01 4441 219

RT-1523F
Improved version of the E

ITT vs GDLS

I've heard that although the ITT and GDLS radios are functionally equivalent the internal construction is completely different and non interchangeable.  This means that extra care is needed to correlate the exact model number with the manual when trying to understand the inner workings of a radio.  Module layouts.  The 1439 and 1523 have the modules both left to right and front to back(LRFB).  The 1523A and 1523D have the modules all lined up like books front to back(Book).

It maybe like this:

ITT:  1439-LRFB, 1523-LRFB, 1523D-Book, 1523E-half size new radio
GDLS: 1523A-Book, 1523B-Book, 1523C-Book

7 June 2005 - ITT says they made all versions except for the 1523D.  Have not yet heard back from GDLS.

The plain version uses the RT-1439, A version uses RT-1523 and D version uses RT-1523D.

VRC-87 Short Range
VRC-88 Short Range optional man pack
VRC-89 Long Range - Short Range
VRC-90 Long Range
VRC-91 Long Range - Short Range optional man pack
VRC-92 Long Range - Long Range


The stack of equipment for SINCGARS is very similar to that for a VRC-64 (PRC-77 in a vehicle).
In comparison photo you can see that the VRC-87 is about as wide as a PRC-77.  The SINCGARS radios are narrower, shorter and heavier than the PRC-77(VRC-64).

VRC-64	SINCGARS	SINCGARS	SINCGARS	Function
PRC-77	RT-1439 or RT-1523()	RT-1439 or RT-1523()	-	Receiver Transmitter Low Power
AM-2060	MX-10862 PS/Adapt	AM-7239() PS/Audio Amp	AM-7238() RF Amp	DC power conditioning
MT-1029	MT-6576	MT-6352	MT-6353	DC power cabling & /or VIC/TSEC interface
Steel mounting shelf	Steel mounting shelf NSN 5340-01-215-1044 for HMMWV	Steel mounting shelf NSN 5975-01-413-1547 for M998	Steel mounting shelf	Mechanical attachment to vehicle sheet metal

Tracked vehicles can cause the DC supply to drop when the hydraulic pump is pulling down the engine RPM.  To counteract this the MX-10862 routs either vehicle DC or BA-5590 DC to the radio.

SR = Short Range
LR = Long Range
-D = Dismount kit for man pack (the -D is different from the D suffix that indicates which radio is used)

Modules

No.	Description	p/n	# pins	Ltr Num	# coax
1	Antenna Tuner BPF		17	L	1 Bot 1 side
2	Remote I/O		41	L	0
3	Main Power Supply		14	L	0
4	Control		61	N	0
5	ECCM		33	L	0
6	2-wire Interface		33	L	0
7	Switch		77	N	0
8	IF Demodulator		17	L	1
9	Rx Tuner Mixer		9	L	3
10	Synthesizer		17	L	2
11	Tx Excit & P.A. Rx LPF		25	L	3
12	Audio P.S.		77	N	0
13	Audio Control		77	N	0
14	Audio I/O		41	L	0
15	Data Rate Adapter		33	L	0

System Connector

Pin	DC  Func	Audio  Func	PA Ctrl  Func	SNAP - FHMUX Func
A				Test
B	?
C				Serial Data
D		Fixed Level
E		Tx voice
F	Batt +15
G				Tune Clock
H			Hi Power (amp on)
J			Pwr Level
K		PT/CT select
L			Filter B (43 - 61.5)
M			Filter A (30 - 43)
N				Tx/Rx
P				Disable
Q				FH
R				Fault 6 1
S		PTT
T				/Tune Gate
U	BA-x90/BB-x90 Batt used by Tray
V			Filter C (61.5 -88)
W	?
X			sidetone disable
Y		wire line rem
Z	Gnd (Batt)
a		wire line rem
b	?
c	?
d	Batt/Adapter sense

Note ¹ Fail 6 is an input for other equipment to report their self test failure during an RT self test.

TM 11-5820-890-20P-1 Figure 57

Alignment plate NSN 5935-01-316-8720 helps the KY-57 cable connect to the RT-1439.  Ref  Sep 1995 PS mag 514 pg 47.

SINCGARS Antenna Connector

The antenna connector is a BNC Jack (female) with a surrounding shroud that has external threads.  A BNC nut is about 0.570" diameter and the I.D. of the shroud is a little larger.  The shroud OD is about 0.8" and 20 TPI.  This may be the same antenna connector used on the PRC-117 and PRC-138?

Do not use a knife to clean twigs out of a vehicle antenna spring since doing so may cut the coax cable inside the spring.  Ref Mar 94 PS mag 496 pg 36.

On the early model RT-1439 that had the solid front panel protectors or the ones with a small hole it was almost impossible to connect a straight BNC cable.  The fix is to use a right angle BNC connector (UG-306B/U NSN 5935-01-032-5404) Ref: July 93 PS mag 488 pg 44.

AS-3683() Short MP Antenna

31" for the tape whip part that has a male 5/16-24 thread like most military antennas.

AS-3916 Low Profile (SLPA) Ant Vehicular

AS-4266 Long MP Ant

AS-3900 Vehicular Ant

AS-3916

OE-254

H-250 Handset

HRCRD (Handheld Remote Control Radio Device) Handset C-12493/U

The main purpose is to allow the radio in a man pack configuration to be controlled by the operator without removing the pack to get access to the front panel.  Can also be used with vehicle configurations for more convenient access to the most frequently used controls.

After setting front panel FCTN switch to REM allows control of:

Channel:  C, M, 1, 2, 3, 4, 5, 6
RF Power: L, M, H, PA
Mode: SC, FH, FHM
COMSEC: PT, CT
Volume: analog
Back light on/off

Note that unlike the C-11291 that can turn the RT off, the HRCRD can NOT turn the radio off.

Uses the 6-wire protocol with 2880 Hz FSK data and straight through audio.
This will work with the RT-1439 since it's related to the revision of the battery box and the only connection is the wire line remote control,  the HRCRD uses the same audio signaling system as the CTRL-MON. 
Manpack: connect cables to RT-AUDIO and CY-8523C
Vehicle: connect  one cable to RT-AUDIO and for RT-1523E use AUX or with AM-7239 use J9 CTRL-MON.
This also means that a PC could do this function with software/hardware that emulated the tone functions.

Manuals

LS-671 Loudspeaker (A15)

LS-688/VRC, NSN 5965-01-382-3222 Manpack Speaker

LS-454

LS-454 Audio Amplifier

It's an audio amplifier intended for use with SINCGARS radios, but there's some strange things about it.
The label says:
Amplifier, Audio - LS-454/U, MFR 31550 (that's ITT), 8143815-1
with the ports labeled:
To MX-10862/VRC
LS-454 Speaker
P1 To Receiver-Transmitter
but there's no nomenclature and no NSN.
The 5 sheet manual that came with it is marked TB 11-5820-890-20-82 and is titled:
Installation and Unit Maintenance Instructions for Amplifier, Audio - LS-454/U to Permit Operation of Loudspeaker LS-454/U with Receiver-Transmitter, Radio RT-1439/VRC and Power Supply Adapter, Vehicular MX-10862/VRC
but there is already a manual with that TB number and it's titled:
Installation Instructions for Installation Kit Electronic Equipment MK-2616 /VRC to Permit Installation of Radio Sets AN/VRC-87/88/90 Series in  a M915A2 Truck, Tractor (NSN 5895-01-361-7606) (EIC: N/A).

To use this amplifier a DC power cable CX-13290 is used between the amplifier and J3 on the back of the MX-10862.  J3 is the connector used for either the HRCRD handset and/or the C-11291 Control-Monitor.  But in this case the cable is only being used for 24 volt DC power and the 6-wire remote signals are not being used.  The Amplifier has an attached coiled audio cable that needs to be connected to one of the AUDIO connectors on the front of the radio.  The cable attached to the LS-454 is attached to a connector on the amplifier. 

This may be a simpler way to get a loudspeaker then using the normal LS-671 but you don't get neither the remote power on-off capability not the remote handset capability with this amplifier.  It probably was priced much below the LS-671.

If you know more about this amplifier please let me know.

When the PRC-25 radio was designed the only thought was to keep water out.  Then there were problems with hydrogen gas buildup that resulted in the box being propelled at the operator when the latches were released and also maybe some explosions.  This resulted in a MWO to retrofit a vent on the battery box to let the hydrogen out.

The battery box on the KY-57 and HYX-57 are designed very similar to the PRC-25 battery box with the vent although they hold the BA-559/U.

But the CY-8523() battery box was designed to withstand the explosion of a single "D" size LiSO₂ cell in the BA-5590/U battery without allowing any stuff to be expelled.  Note that a PRC-25 type vent can not get enough gas out fast enough to be of use.  But it is not designed to contain an explosion of more than one cell like might happen if you tried to charge a BA-5590/U and the batteries internal protection diodes failed (like might happen after long term hot storage and when hot).  This may have been related to why the Battery Tray has had the charging function deactivated, but that does not make sense since the Battery Tray uses pin 3 for charging and that pin is only active on rechargeable batteries (There's not even any metal in the pin 3 position on a BA-5590).  If you know about this let me know.

CY-8523A 

The CY-8523A has two telephone type wire terminals to support the tone based remote control of the radio.  The CY-8523C replaces these with a circular connector that mates to the HRCRD for tone control.

TM 11-5820-890-20P-1 Figure 12

CY-8523B

TM 11-5820-890-20P-1 Figure 208

CY-8523C  NSN 6160-01-424-8514

The CY-8523C replaces the two wire line terminals with a circular connector to support the HRCRD handset.  This makes operating the radio while it's on your back much easier.

The HRCRD connector on the battery box is the same as the connector on the CY-8664 Battery Tray and the PP-8249 Battery Charger.
The CX-13290 cable mates to all of these.  The cable plug is a MS3116F10-6P.  This is also the same cable used with the C-11291 Control-Monitor.

TM 11-5820-890-20P-1 Figure 12A

The original design supported charging the battery but this was later discontinued.  The design does take into account the function of pin 3 which is connected to pin 1 only in rechargeable BB-series batteries.  So it's a mystery why the charging function was removed.  One possible reason may be that it correctly charged the BB-590 Ni-Cad but it would over charge a BB-390 Ni-MH.  Note that a Ni-MH tends to get very hot at the end of charge whereas the Ni-Cad does not, that's why the BB-390 has the temperature sensors that are not part of the BB-590.   Note that the mechanical keying difference between primary and secondary can NOT be used since the radio needs to work with either kind.

TM 11-5820-890-20P-1 Figure 13

Cabling Battery Box/Tray

These are cables used to interconnect equipment outside a radio.

There are more cables that have part numbers rather than being nomenclatured.