- Introduction
     - Locating Radio Model Numbers
     - Locating Radio Unified Chassis Numbers
     - VHF Model Information
     - VHF Railroad Model Information
     - UHF Model Information
     - PAC-PL and PAC-RT Vehicle Repeater Model Numbers
     - Service Manuals
     - Programming
     - Audio Routing
       - Tx Audio Routing
     - Audio Muting Interface
     - Repeater Conversions
     - Frequency Agility
     - EPROM Conversion
       - Conversion Page
     - Syntor Accessories
     - Standard Syntor Cable
     - Additional Information
       - GLOSSARY
       - WEB LINKS
   - HOME



This page has model charts and information for the original Syntor radios. These radios are very different from any other radio with Syntor in their name.

Programming is done outside the radio and uses a different one time only PROM memory chips for the frequencies and PL tones (the PL tones are optional). When you program a channel or PL tone into one of these chips it can never be changed or reprogrammed again. You must get a new chip and start over. These chips have not been made in years and it is very hard to find ones that have not already been programmed. Be aware some substitute part number chips will work in the radio, but require completely different programming hardware than the chip Motorola used. Batlabs has more information and links about programming these radios. The links page also has programming software links.

This site also has a construction project to convert the Syntor frequency PROM over to a standard 2716 or 27C16 EPROM, along with accessory part numbers, standard Syntor cabling and other information. Unlike the standard PROM the 2716 EPROM can be erased and reprogrammed with the right equipment.


Locating radio model numbers:

Please see the locating radio model numbers instructions on the home page.


Locating radio unified chassis numbers:

On several VHF radios I have found the unified chassis number stamped in ink on the preselector housing (next to the optional receiver preamplifier plug-in slot). The number was abbreviated with the "HU" part missing and ended with the letter O (i.e. D1037O). The factory frequency list on the VCO cover confirmed this was the correct unified chassis number.


VHF Model Information:

T  T = Trunk Mount
_  4 = 40 watt, 6 = 60 watt, 8 = 75/110 watt adjustable
3  3 = VHF
_ _ _  SRA = Standard Radio, TXA = Secure Capable
_  1 = Carrier Squelch, 3 = PL Squelch, 6 = DPL Squelch
_  1 = 1 channel, 9 = 4 ch., 2 = 8 ch., 8 = 12 ch., D = 16 ch., J = 16 ch. with Talkaround
_  A, B, C, etc. revision
K  K = Package radio sold with accessories (microphone, speaker, etc.)

Chassis #  Description
HUD1036A  136-144 MHz, 40 Watt
HUD1037A  146-150.8 MHz, 40 Watt
HUD1038A  150.8-162 MHz, 40 Watt
HUD1039A  162-174 MHz, 40 Watt

 HUD1041A  136-144 MHz, 60 Watt
 HUD1042A  146-150.8 MHz, 60 Watt
 HUD1043A  150.8-162 MHz, 60 Watt
 HUD1044A  162-174 MHz, 60 Watt

HUD1047A  146-150.8 MHz, 75/110 Watt
HUD1048A  150.8-162 MHz, 75/110 Watt
HUD1049A  162-174 MHz, 75/110 Watt

Model #  Description
HLD4035A  Range 1 VCO - 136-144 MHz
HLD4036A  Range 2 VCO - 146-156 MHz
HLD4037A  Range 3 VCO - 150.8-162 MHz
HLD4038A  Range 4 VCO - 162-174 MHz


VHF Railroad Model Information:

R  R = Railroad
_  3 = 30 watt, 4 = 45 watt
3  3 = VHF
RW  RW = Standard Railroad radio
_  F = 36/12 VDC, G = 36 VDC, E = 12 VDC, C = 64/12 VDC, H = 64 VDC
8  8 = 12 ch.
_  A = AAR Compatible Radio, D = Clean Cab Radio, E=Radio Only

Chassis #  Description
TLD2383A  150.8-162 MHz, Upper Housing Kit, 12 VDC
TLD2384A  162-174 MHz, Upper Housing Kit, 12 VDC

TLD2373A  150.8-162 MHz, Upper Housing Kit, 64/12 VDC
TLD2374A  162-174 MHz, Upper Housing Kit, 64/12 VDC

TLD2513A  150.8-162 MHz, Upper Housing Kit, 36/12 VDC
TLD2514A  162-174 MHz, Upper Housing Kit, 36/12 VDC

TLD2403A  150.8-162 MHz, Lower Housing Kit
TLD2404A  162-174 MHz, Lower Housing Kit


UHF Model Information:

T  T = Trunk Mount
_  3 = 30 watt, 4 = 50 watt, 6 = 75 watt, 7 = 100 watt
4  4 = UHF
_ _ _  SRA = Standard Radio, TXA = Secure Capable
_  1 = Carrier Squelch, 3 = PL Squelch, 6 = DPL Squelch
_  1 = 1 channel, 9 = 4 ch., 2 = 8 ch., 8 = 12 ch., D = 16 ch., J = 16 ch. with Talkaround
_  A, B, C, etc. revision
K  K = Package radio sold with accessories (microphone, speaker, etc.)

Chassis #  Description
HUE1036A  403-430 MHz RGI, 30 Watt
HUE1037A  450-470 MHz RGII, 30 Watt
HUE1038A  470-494 MHz RGIII, 30 Watt
HUE1039A  494-512 MHz RGIV, 30 Watt
HUE1121A  403-430 MHz RGI, 30 Watt, Rx Preamp
HUE1122A  450-470 MHz RGII, 30 Watt, Rx Preamp
HUE1123A  470-494 MHz RGIII, 30 Watt, Rx Preamp
 HUE1124A  494-512 MHz RGIV, 30 Watt, Rx Preamp

HUE1041A  403-430 MHz RGI, 50 Watt
HUE1042A  450-470 MHz RGII, 50 Watt
HUE1043A  470-494 MHz RGIII, 50 Watt
HUE1044A  494-512 MHz RGIV, 50 Watt
HUE1131A  403-430 MHz RGI, 50 Watt, Rx Preamp
HUE1132A  450-470 MHz RGII, 50 Watt, Rx Preamp
HUE1133A  470-494 MHz RGIII, 50 Watt, Rx Preamp
HUE1134A  494-512 MHz RGIV, 50 Watt, Rx Preamp

HUE1046A  403-430 MHz RGI , 75/100 Watt
HUE1047A  450-470 MHz RGII , 75/100 Watt
HUE1048A  470-494 MHz RGIII, 75/100 Watt
HUE1049A  494-512 MHz RGIV, 75/100 Watt
HUE1141A  403-430 MHz RGI , 75/100 Watt, Rx Preamp
HUE1142A  450-470 MHz RGII , 75/100 Watt, Rx Preamp
HUE1143A  470-494 MHz RGIII, 75/100 Watt, Rx Preamp
HUE1144A  494-512 MHz RGIV, 75/100 Watt, Rx Preamp

As an example try this model number; T44TXA3800BK. It is a trunk mount, 50 watt, UHF, secure capable, PL squelch, 12 channel, B revision radio. To find the frequency range look at the frequency list on the VCO cover then find and match up the unified chassis number or locate the Unified Chassis number inside the radio.


 Please see the PAC page for this information.


Service Manuals:

Motorola manuals have a revision letter at the end of the manual part number (i.e. 68P81043E40-O is an "O" revision and 68P81043E40-B is a "B" revision). These revision letters separate the older manuals from newer ones. The -O revision is for the original manual in that part number series. Keep in mind, that Motorola will sometimes supersede a series of manuals for a particular radio with a new manual that has a new part number. When they do this, the first manual with the new part number will be a -O revision, but it will be newer than any of the manuals with the old part number, regardless of the old manual revisions. For this reason, not all manuals with an "O" revision can be considered "OLD" manuals.

Motorola has been know to drop valuable information from manuals as they release newer revisions. When different internal circuits of a radio are redesigned and given new assembly numbers, the information (schematics, parts lists, etc.) for the old assembly number can be completely dropped in a newer revision manual. If you work on these radios, sometimes you may need a specific older or newer version of a manual. When I have the information I will attempt to point out important differences in different manual revisions.

SYNTOR Radio Service Manuals
Part # Description Models
 68P81043E40  VHF 136-174 MHz, 40/75/110 Watts T43, T63, T83
 68P81048E70  VHF DVP, 136-174 MHz, 40/110 watts T43, T83
 68P81044E90  RSX-410 Railroad, 150.8-174 MHz, 30/45 Watts R33, R43
 68P81043E45  UHF 403-512 MHz, 30/50/75/100 Watts  T34, T44, T64, T74
 68P81048E75  UHF DVP, 403-512 MHz, 30/50/100 Watts  T34, T44, T74

SYNTOR Accessories Service Manuals
Part # Description
 68P81106E45  Systems 90 Touch Tone Encoder
 68P81106E46  Selective Signaling Touch Tone Decoder
 68P81102E25  Micor System 90 Quick Call Selective Signaling Decoder
 68P81102E27  Systems 90 Quick Call II Mobile Paging Decoder for Mitrek / Syntor X
 68P81106E59  Syntor System 90*s Multiple Private Line Encoder
 68P81102E31  System 90 / System 90*s Single Tone Encoder
 68P81108E05  Systems 90 / Systems 90*s Electronic Siren and Public Address System
 68P81109E75  Mobile Public Address
 68P85900C35  Systems 90 Voice Privacy Adaptor
 68P80100W10  MDC-600 Signaling System
 68P80100W50  MVS-20 Mobile Voice Storage with MDC-600 Signaling System
 68P81106E95  Syntor Multiple Private Line Mobile Encoder
 68P81106E95  Syntor Multiple Digital Private Line Mobile Encoder
 68P81110E82  Syntor Options W85 Weather-Resistant Control Package
 68P81110E62  Syntor System 90*s Accessory Group Installation
 68P80200W07  Syntor Systems 90*s Accessory Group Installation (MDC600, MVS20)
 68P81111E87  Syntor Railroad Radio RSX-410 Series PROM Module Security Set Screws
 68P81102E60  Handset Hangup Units
 68P81114E07  Touch-Tone Encoder Palm Microphone
   Please see the PAC page for manual information on the PAC-PL and PAC-RT.

Test Equipment Service Manuals
Part # Description
 68P81069A78  Radio Test Set R-1033A, RTL-4118A and RTL-4119A
 68P81123E37  RTK-4043A Cable (R-1033A) for Micor, MSR2000, Syntor, Syntor X Radios
 68P81011A01  Portable Test Set Models S1056A, S1057A, S1058A and S1059A
 68P81121A01  Tek-37 and Tek-37A Test Set Cable Adapter (S1056A-S1059A)
 68P81069A30  "Digital Private Line" Test Set SLN-6413A
 68P81021A05  S1053C A.C. Voltmeter
 68P81069A94  R-1011B 40 Volt, 40 Amp., Variable Bench Power Supply
 68P81069A34  R-1200A Service Monitor



The Syntor can be programmed with the original Motorola R1800/R1801 series suitcase programmer, EPROM and adapter. Or you can use one of the many aftermarket programs to create the program then burn the PROM in a PROM programmer. Check the Syntor page on or the links to find some of the programs. Some of them let you select high or low receiver injection, which is good trick to retune the 150.8 MHz range radio for HAM use without modifying the VCO tuning pads.


Audio Routing:

The receive audio routing is all done through the radio cable pins J6-20 (Detected Audio), J6-2 (Volume - Receiver Audio) and J6-25 (Sidetone). J6-20 is the received audio output that goes to the volume control in the control head. J6-2 is the received audio input that gets the received signal from the control head volume control. All of the receive audio shaping (RAS) is done internally after the J6-2 volume control connection. J6-20 Sidetone is an audio input for external options to send alert signal tones directly to the radio's speaker. The alert tones are basically square wave signals like beeps, not normal undistorted audio sine wave signals. Instead of having alert tones, the Sidetone input can also be jumpered (JU451 and JU453 installed) for direct sine wave audio input to the audio amplifier (no RAS conditioning is used on this direct connection and a shielded cable wire should be used for sine wave signals). The later models of the Interface Board have a second duplicate Sidetone connection at J6-6.

The transmit audio routing is show in this drawing. As shown J6-15 Mic. Hi is pre-emphasized, deviation limited and filtered (i.e. the filter removes the splatter). J6-27 can be used for external Tx encode PL/DPL audio or high speed data audio (never both PL/DPL and data at the same time). The Interface Board jumper JU3 can be installed to enable this external connection when no internal PL/DPL Board is installed in the Syntor. Some of the optional internal PL/DPL boards have their own built in jumpers that do the same job as JU3 as well as allowing their PL/DPL encode audio to be disconnected. The drawing also includes an optional J6-18 custom modification for repeater audio Tx conversions and low speed data Tx audio.


Audio Muting Interface:

The received audio J6-20 (Detected Audio) is sent to the control head squelch control potentiometer and back to the radio's internal squelch hybrid via J6-19 (Squelch).

The receive audio muting interface is available on later model Interface Boards at J6-7 (Channel Activity), J6-24 (Audio Mute) and J6-35 (Detected Audio Disable). Early Interface Boards will require custom wiring for these connections (only if you need them).

The Channel Activity and Audio Mute outputs are generated internally by the squelch hybrid circuit. When the Channel Activity line is active, it simply means the receiver has detected a received signal (it can also mean the squelch control is adjusted to open the squelch when no received signal is present). The Channel Activity does not care about any received PL or DPL signals (i.e. it will be active even when the PL or DPL does not match the received decode PL or DPL, if the PL/DPL option board is installed). Channel Activity is not used all by itself for the squelch decision to mute the receiver audio, so it is processed and sent to the squelch hybrid Audio Mute output. When the squelch hybrid Audio Mute output is high, the received audio section is muted and when it is low the received audio is active (i.e. you can hear the received signal in the speaker). These high and low squelch hybrid Audio Mute output voltage levels are not appropriate for driving external control circuits like a repeater controller, so a custom single transistor switching circuit must be used to condition this signal if it hooked to an external device. The squelch hybrid Audio Mute output is sent to J6-24 where it can be used as an output. The J6-24 Audio Mute can also be used as an external input to control the audio muting by imposing + 5 volts on this pin or by grounding it through a 220 ohm resistor. This is how the internal optional PL/DPL Board controls the Audio Mute when decoding a proper Rx PL or DPL signal (if you have a PL/DPL board installed then J6-24 should not be used for an external control input, use it only as an output, if at all). When the J6-24 Audio Mute is pulled high (to + 5 volts) it overrides the internal squelch hybrid circuit and mutes the received audio. When J6-24 is pulled low (i.e. grounded with a 220 ohm resistor) it overrides the internal squelch hybrid circuit and un-mutes the received audio. If J6-24 is only pulled high when no PL is detected (i.e. force the audio to mute) and never pulled low low when the correct PL/DPL is detected (JU13 is removed on some models of PL/DPL boards), it works with the internal squelch hybrid circuit to adjust the receiver sensitivity through the squelch control potentiometer (this is used to make the radio less sensitive when unwanted weak signals with the correct PL or DPL are causing interference on your receive frequency). J6-24 should never be shorted directly to ground by any external control circuit as it might damage the squelch hybrid, PL/DPL Board or Interface Board transistor Q1.

The Detected Audio Disable control input (also know as Detector Mute) on J6-35 can be wired to P201 on the main board and used to mute the receiver audio detector (the Mobile Voice Storage option is the only thing I am aware of that uses this). When hooked up to P201, this control input mutes the U201 detector audio before it even gets to the squelch hybrid, so the squelch control has no function while the detected audio is muted.


Repeater Conversions:

As mentioned in the home page introduction you need two of these radios to make a repeater conversion. Either use J6-7 Channel Activity as the repeater controller Carrier Operated Relay conrol or make a custom voltage level converter switch (a single transistor and a few resistors) for the J6-24 Audio Mute output and use it as the Carrier Operated Relay control signal. The difference between them is the J6-7 Channel Activity will ignore any internal Syntor PL/DPL option board (i.e. it is controlled strictly by the control head squelch adjustment setting) and J6-24 Audio Mute will have any optional PL/DPL detect included (when an optional internal PL/DPL board is installed it can completely take over control of the J6-24 Audio Mute). If your repeater controller has a CTCSS or PL detect input, install and setup an optional Syntor internal PL/DPL Board and make the voltage level converted J6-24 Audio Mute the CTCSS/PL control signal. Then make J6-7 Channel Activity the Carrier Operated Relay control signal.

The received audio source comes from the J6-20 Detected Audio. For FM voice signals this audio will have already been pre-emphasized by the transmitter the voice signal originated from, so this detected audio will be pre-emphasized. If you feed this pre-emphasized audio to the J6-15 Microphone Hi input, it will get pre-emphasized again giving it double pre-emphasis and very noticeably distorting the audio frequency response. As an alternative you can make the J6-18 Flat Audio modification show here and use it instead of J6-15. You can also make your own custom external de-emphasis circuit (i.e. de-emphasize J6-20) or use the PL/DPL filter receiver section alternative modification (next paragraph below) and still use J6-15 if you want. One advantage of the J6-18 modification is the microphone can still be connected to J6-15 and used for on site Tx operation and testing. Also using J6-20 Detected Audio for the repeater audio means you can still use the volume control and audio section / speaker for on site monitoring.

The J6-20 Detected Audio will pass any received PL or DPL signal on to the transmitter. In this case you will need to make a custom PL filter for the detected audio and install it. As an alternative you can use the Syntor internal audio signal after it is de-emphasized and filtered (i.e. RAS) to remove the PL/DPL, by making a custom modification to output this RAS audio to the J6 connector (you should also disable the last power output section of the audio amplifier and make the volume control internal to the radio as adjusting it will alter the audio level sent to the transmitter - the audio section will not be usable for on site monitoring).

As repeaters can have a 100 % duty cycle, it is recommended the Tx power level be tuned down to no more than 1/2 the rated power level and an external cooling fan should be installed over the PA heat sink if additional cooling is needed. The Tx output should be checked with a spectrum analyzer to make sure there are no spurious emissions when the power is reduced.

You have probably had the experience of being mobile in a noisy vehicle and having one station with such weak audio levels you have to turn up the volume control, only to get blasted by the next station with normal audio. Here is one solution to this problem. If you feed the Tx audio though the deviation limiter (J6-15 or the J6-18 modification) and you adjust the transmitter to hard limit the deviation at no more than 5 KHz, then you can slightly overdrive the Tx audio into the deviation limiter on purpose. There will be a slight amount of distortion when the deviation limiter kicks in, but this is only communications audio, not some high quality home entertainment system (when properly adjust any distortion will not be noticeable). The advantage of this is someone that speaks softly or holds their microphone too far away will have their under deviated signal boosted by the repeater transmitter and the transmitter will not be able to over deviate on the normal signals. BTW, this should never be done to a link repeater signal or if the repeater Tx output is used for signaling (DTMF, QC-II, MDC, etc.) as distortion will get noticeably amplified after passing through several more links and the gain boost can mess up signaling systems causing them to malfunction. Two drawbacks of this particular approach are the squelch tail noise burst from the repeater receiver will also be boosted and if you do not filter any Rx PL/DPL out of the detected audio it will also get boosted up to above normal deviation levels in the repeater Tx output.

When adjusting the Tx deviation for repeater voice signals, keep in mind that is is different than adjusting deviation for a microphone. The Rx output has a much wider output range than a microphone. You must temporarily overdrive the Tx modulation input to correctly adjust the Tx deviation limiter (IDC). Failure to do this can allow an over deviated user's radio to over deviate your repeater and cause your repeater to violate FCC rules and regulations.

It appears the PL/DPL board could be modified for dual level squelch control. It would un-mute when the correct PL or DPL is detected, even for a weak signal. However, the squelch control could be adjusted such that a modified PL/DPL Board would allow the radio to un-mute without the correct PL or DPL, but only for strong signals. This is the opposite of the previously described normal method of eliminating weak unwanted signals in the Audio Muting Interface section above. This would allow strong stations to work the repeater without a PL or DPL, but require PL or DPL for weaker stations. This should eliminate weak signal interference on the repeater input without absolutely requiring the use of PL or DPL. The PL DPL board would have to be modified to only pull the J6-24 Audio Mute line down to ground through a 220 ohm resistor when a valid PL or DPL was received (i.e. un-mute the audio) and to never pull J6-24 Audio Mute up to + 5 volts (i.e. thereby allowing the squelch hybrid circuit to determine when the audio is muted). Then you would have to turn the squelch control up far enough to eliminate any interference. BTW, if your repeater controller has a COR input, a PL/DPL detect input, and is programmable to use both inputs together in a logical OR fashion to key the transmitter, then you can accomplish this weak signal PL/DPL and strong signal performance without making any modification to the PL/DPL Board.

There are aftermarket PL/DPL filters, pre-emphasis circuits, de-emphasis circuits and automatic audio gain control systems available for repeater applications if you do not want to make your own.

Here is a list of the modifications done to a Syntor to make a repeater transmit radio:

  1. The cable wire for J1-19 (Squelch) was moved to J1-18 to provide a shielded audio input line for the Flat Audio modification. The plus side of a 63 volt 10 uf capacitor was soldered at J6-18 and its minus side to P2-4 (Spare) (insulators were slipped over its leads). On the bottom of the radio under the RF Board shield, a 1/8 watt 12 k resistor was soldered between P2-4 (Spare) to U502 pin 4 (the resistor and its wires had an insulating sleeve placed over them).
  2. Pins at J6-2 and J6-20 were removed from the connector body, left inside the connector housing and taped over to prevent any shorts.
  3. A new pin was placed at J6-2 and connected to ground. This should help prevent any unnecessary power drain from the unused receiver.
  4. New pins were placed at pins J6-19 and J6-20 with a 3.3 K resistor connected between them to close the squelch gate circuits and activate the audio section mute. This should help prevent any unnecessary power drain from the unused receiver.

Here is a list of the modifications done to a Syntor to make a repeater receive radio:

  1. The single transistor voltage level converter input wire was connected at P1-8 (Audio Mute) on the solder side of the RF Board.
  2. The transistor voltage level converter output (i.e. the transistor collector) wire was connected to P1-10 (Decimal Select Talk-Around at J6-12) on the solder side of the RF Board. J6-12 was not connected anywhere else besides P1-10 inside the radio, so it was just an available unused pin at J6-12 and the radio cable already had a wire at this pin location.
  3. The manual was used to find a suitable ground on the solder side of the RF Board for the transistor voltage level converter emitter wire.
  4. The voltage level converter NPN transistor and its two bias resistors were put on a perforated board, wires were soldered for the 3 above connections and the entire perf board was wrapped in electrical tape. The bias resistors values were determined empirically (i.e. you might need different values as my setup may not be reproducible over a wide variety of Syntor radios). Both turned out to be 10 K with one in series with the transistor base and the other connected from the transistor base to ground (the emitter in this case). The repeater controller had its own internal pull up resistor so only the transistor collector was wired directly to the J6-12 output. The signal at J6-12 for this type of interface is either a high impedance when it is not active or a short to ground when it is active.
  5. An unused wire in the cable connector was moved to J6-7 (Channel Activity). The actual wire used will depend on your cable.

The transmit and receive cables were wired to a double sided barrier strip and attached with the barrier strip screws (the Rx and Tx radio F1 frequency select lines were both grounded and the other F2 through F12 lines were not connected). The barrier strip positions were labeled:

  1. Volume
  2. Squelch
  3. Detected Audio
  4. Rx Audio Shield
  5. Tx Audio Shield
  6. Tx Flat Audio
  7. Mic. Hi
  8. Audio Mute (PL Detect - I used an internal Syntor PL Board)
  9. Channel Activity (COR)
  10. PL On/Off (HUB)
  11. PTT
  12. Speaker Hi
  13. Speaker Low
  14. Rx Chassis
  15. Tx Chassis
  16. Switched B+ (from clamshell control head)

The modified receive and transmit cables were cut to length and terminals for the barrier strip were crimped on and soldered (actually some old 4 frequency Micor cables were used, the gauge of the large red and black power wires were matched to the Tx radio power level). Then a clamshell control head, the repeater controller cable, the receiver cable and transmit cable was wired up to the barrier strip (one of the cut off Micor cable ends was used for the clamshell control head). A fused power wire was provided to the clamshell control head, the PTT reference lines were wired to switched B+, a microphone and speaker were plugged into the clamshell. The PL On/Off (HUB) was wired to a programmable repeater controller logic level output for DTMF remote control. All unused cable wires were tie wrapped back onto their own cables, strain releifs were attached to the cables near the barrier strip and everything except the power supply, radios and repeater controller were mounted on a 19 inch rack panel. Both the Rx and Tx radio large red and black power wires were fused and connceted to the power supply (the Rx audio amplifier will not function without power from these wires). Another wire was fused and attached to the clamshell control head 22 pin black connector at pins 12 and 13 . All the power fuses were the same ones used in a normal Syntor installation (our repeater 70 amp power supply and battery backup are more than capable of blowing the 40 amp fuses). Another fused power wire was connected to the repeater controller. It all makes a very clean easy to work on installation.


Frequency Agility:

The web site (see the Syntor model specific information) has links to information on converting these radios to be frequency agile via thumb wheel frequency controls (look for Syntor VHF/UHF modification instructions). The VHF conversion can cover the entire 144 to 148 MHz HAM band in 5 KHz steps. There are other links to frequency agile conversion kits on Batlabs.


EPROM Conversion:

The Syntor radios come with a U1100 16 channel (82S129) or 32 channel (82S131) one time only programmable PROM which is used to control the radio's synthesizer (i.e. the receive and transmit frequencies). Jumper JU1101 will be installed in 16 channel radios and removed in 32 channel radios (a 32 channel control head and cable with 12 frequency select wires is required for proper operation). Since the PROM can not be reprogrammed once a channel has already been programmed, it must be replaced with a brand new PROM which can be programmed. New PROMs are getting very hard to find and the easier to find substitute PROMs that will plug into the Syntor PROM socket, program differently than the original PROMs (i.e. the PROM programmer must be able to handle the substitute PROMs).

One solution is to make a converter that will allow the use of a reprogrammable EPROM. This device allows you to use standard 2716 or 27C16 EPROMs to program the transmit and receive frequencies. There is enough room on the EPROM for 128 channels, but the Syntor can only make use of up to 32 channels. By changing the wiring shown in the construction project details below, you should also be able to use 2816 EEPROMs (it was reported to me that a 2816 worked, but Q1101 had to be jumpered - see below).

The power to the U1100 chip has its power switched by transistor Q1101. The power to the U1100 socket is only turned on when the synthesizer wants to read the frequency information. Some substitute EEPROMs do not recover quickly enough after the power is turned on to read correctly (the original PROM has a very fast recovery). If this happens (i.e. your substitute EEPROM chip does not work), try shorting out the emitter and collector on transistor Q1101 to supply uninterrupted +5 volt power to U1100. This is never a problem with the original PROM. Remember to use the correct wiring if you choose a chip other than a 2716 for this construction project.

Remember to take anti-static precautions and always pay very careful attention to the pin 1 orientation on the chip and socket. Be careful when pulling a chip from its socket. PC board traces can be accidentally damaged if you are not very careful about where you place any tools used to pry a chip out. A real chip removal tool should be the safest thing to use.

Click here for a construction project details.

Check out the Web Links page Ries Labs links to see a similar construction project done by Ries Labs.

Brinkley Electronics has manufactured PROM converters and is selling them (Web Links page). I have not tried one yet, but they look nice. BTW, they also have a MCX-100 converter (Web Links page).


Syntor Accessories:

HCN1004A - Clamshell Control Head, 1 Frequency
HCN1005A - Clamshell Control Head, 4 Frequency
HCN1007A - Clamshell Control Head, 12 Frequency
HCN1009A - Clamshell Control Head, 8 Frequency
HCN1011A - Clamshell Control Head, 16 Frequency
HCN1018A - Clamshell Control Head, 32 Frequency
HCN4000A - Clamshell Control Head, Weather Resistant, 1 Frequency
HCN4001A - Clamshell Control Head, Weather Resistant, 4 Frequency
HCN4002A - Clamshell Control Head, PL/DPL Monitor Switch, Weather Resistant, 1 Frequency
HCN4003A - Clamshell Control Head, PL/DPL Monitor Switch, Weather Resistant, 4 Frequency

HHN4002A - Single System 90*s Housing w/ Long Trunnion (for use with Standard Clamshell Control Head)
HHN4003A - Double System 90*s Housing w/ Long Trunnion
HHN4004A - Single System 90*s Housing w/ Standard Trunnion

HCN1000A - System 90*s Control head, 1 Frequency
HCN1001A - System 90*s Control head, 4 Frequency
HCN1010A - System 90*s Control head, 8 Frequency

HLN1018A - System 90*s Public Address
HLN1019A - System 90*s Singletone Encoder, 1 Tone
HLN1020A - System 90*s Singletone Encoder, 5 Tone
HLN1021A - System 90*s Auxiliary Switch Panel
HLN1022A - System 90*s Voice Privacy Adaptor
HLN1023A - System 90*s DTMF Encoder
HLN1024A - System 90*s DTMF Selective Signaling
HLN1025A - System 90*s Siren, Wail, Yelp, Steady Pitch
HLN1026A - System 90*s Siren, Wail , Yelp, Hi-Lo
HLN1027A - System 90*s Multiple DPL Encoder, 4 Code
HLN1028A - System 90*s Multiple DPL Encoder, 8 Code
HLN1117A - System 90*s MVS-20 Mobile Voice Storage
HLN1145A - System 90*s MVS-20 Mobile Voice Storage Retrofit
HLN1068A - System 90*s MDC-600 Unit Identification
HLN1077A - System 90*s MDC-600 Selective Call Decoder
HLN1069A - System 90*s MDC-600 Selective Call Encoder/Decoder
HLN1070A - System 90*s MDC-600 Five Status w/ Alarm
HLN1071A - System 90*s MDC-600 Five Status, 1 Message
HLN4343A - System 90*s MDC-600 Emergency Footswitch
HLN4349A - System 90*s MDC-600 Emergency Pushbutton
HLN1013A - System 90*s Channel Scan Monitor w/ Priority Select, 4 Frequency
HLN1014A - System 90*s Channel Scan Monitor w/ Non-priority Select, 4 Frequency
YLN1011A - System 90*s Channel Scan Monitor w/ Non-priority Select, 8 Frequency
YLN1000A - System 90*s Digital Decoder Mobile Paging (1500 Hz)
YLN1014A - System 90*s Digital Decoder Mobile Paging (2805 Hz)

Please see the PAC page for information on the PAC-PL and PAC-RT.

HLN4016A - DVP Physical Security Housing, One Code
HLN4017A - DVP Physical Security Housing, Two Code

HMN4000B - Palm Microphone, Weather Resistant
HMN4002A - Palm Microphone, Standard
TMN6116A - Palm Microphone, Noise Canceling
HMN1022A - Palm Microphone, DTMF
TMN6057A - Handset, Simplex
TMN6067A - Handset, Duplex
TMN6090A - Headset & Audio Preamplifier
TLN5557A - Headset Footswitch
HLN4188A - Microphone Hang-up Box
HLN4519A - Handset Hang-up Cradle, Carrier Squelch, Audio Switching
HLN4504A - Handset Hang-up Cradle, Automatic Monitor, PL/DPL Disable Switch
HLN4505A - Handset Hang-up Cradle, Carrier Squelch, Non-audio Switching

HSN4005A - Speaker, 15 watts, 8 Ohm, 8' cable
HSN4006A - Speaker, 15 watts, 8 Ohm, 25' cable
HSN4011A - Speaker, 20 watt, 8 Ohm, 12' cable, weather resistant

HLD4051A - Receiver RF Preamplifier, 136-144 MHz (installs inside the radio)
HLD4052A - Receiver RF Preamplifier, 146-174 MHz (installs inside the radio)
HLN4012A - Transmitter Time-out Timer, 1 minute (installs inside the radio)
HLN4175A - Private Line Audio Filter
HLN4373A - MDC-600 Retrofit Board (installs inside the radio)
HLN1145A - MVS-20 Retrofit Board (installs inside the radio)


Standard Syntor Cable:

22 pin BLACK
22 pin BLUE
A      A- (Black Wire)
B      A+ (Red Wire)
21    Audio Shield & Squelch Shield
20    Volume - Receiver Audio (Input)
     Switched B+ to Accessories
  11  F1 Frequency Select Line (Input)
  3  F4 Frequency Select Line (Input)
     Sidetone* (Input)
     Channel Activity* (Output)
14    PTT Reference (Input)
9    Chassis (jumpered to J1 pin 11)
4    PL/DPL Disable (Input)
     B- (jumpered to J1 pin 9)
     Decimal Select Talk-Around (Input)
  1  F3 Frequency Select Line (Input)
  22  F2 Frequency Select Line (Input)
11    Mic. High (Input)
22    PTT (Input)
6    Speaker Audio Low (Output)
17    Squelch (Input)
16    Detected Audio (Output)
3    Speaker Audio High (Output)
1    Switched B+ (Input)
  4  F5 Frequency Select Line (Input)
     Audio Mute* (Input / Output)
     Sidetone (Input)
  17  (Unused)
5    PL / DPL Audio (Input)
  14  F6 Frequency Select Line (Input)
  9  F7 Frequency Select Line (Input)
  7  F8 Frequency Select Line (Input)
  8  F9 Frequency Select Line (Input)
  19  F10 Frequency Select Line (Input)
  10  F11 Frequency Select Line (Input)
  6  F12 Frequency Select Line (Input)
     Detected Audio Disable* (Input)

1-B17   22  Switched B+
2      Hang Up Box Gnd.
3-B20   21  Speaker Audio Hi
4-15   10  PL/DPL Disable
5   27  N.C.
6-9-19-B5   17  Speaker Audio Low
7      N.C.
9-6-19-B5   9  Chassis
10   1  Squelch Shield
11   15  Mic. High
12      A+ Unswitched
13      A+ Ignition Switch
14   8  PTT Reference
15-4      Hang Up Box Switched
16-B15   20  Detected Audio
17   19  Squelch
19-6-9-B5      (Speaker Audio Low)
20   2  Volume - Receiver Audio
21   1  Audio Shield
22-B18   16  PTT

1   13  F3 Frequency Select Line
3   5  F4 Frequency Select Line
4   23  F5 Frequency Select Line
5-B6-B9-B19      Chassis
6   34  F12 Frequency Select Line
7   30  F8 Frequency Select Line
8   31  F9 Frequency Select Line
9   29  F7 Frequency Select Line
10   33  F11 Frequency Select Line
11   4  F1 Frequency Select Line
12      Handset Received Audio
14   28  F6 Frequency Select Line
15-B16      Detected Audio
16      DVP Audio In
17-B1   26  Switched B+
18-B22      PTT
19   32  F10 Frequency Select Line
20-B3      Speaker Audio
21      Switched Speaker Audio
22   14  F2 Frequency Select Line

There are several different varieties of Syntor cables. The most common differences are the number of frequency select wires (F1 - F12).

The System 90 Micor cables can be interchanged with Syntor cables (some wires may need moving and some Micor cables may not have enough frequency control wires). Also be sure to match the Micor main red and black power wire gauges (i.e. the thickness of the wire) with the current requirements of the Syntor radio.

 HKN4030A  18', neg. ground, up to 4 frequency, non-weatherproof
 HKN4031A  22', neg. ground, up to 4 frequency, non-weatherproof
 HKN4032A  18', neg. ground, up to 32 frequency, non-weatherproof
 HKN4033A  22', neg. ground, up to 32 frequency, non-weatherproof
 HKN4034A  22', pos. ground, up to 4 frequency, non-weatherproof
 HKN4035A  22', pos. ground, up to 32 frequency, non-weatherproof
 HKN4036A  22', neg. ground, up to 4 frequency, weather resistant
 HKN4037A  22', pos. ground, up to 4 frequency, weather resistant
 HKN4038A  10', neg. ground, up to 4 frequency, non-weatherproof
 HKN4039A  10', neg. ground, up to 32 frequency, non-weatherproof
 HKN4090A  DVP, 18', neg. ground, up to 32 frequency, non-weatherproof
 HKN4091A  DVP, 5', neg. ground, up to 32 frequency, non-weatherproof
 HKN4092A  DVP, 5', pos. ground, up to 32 frequency, non-weatherproof
 HKN4093A  DVP, 22', pos. ground, up to 32 frequency, non-weatherproof
 HKN4104A  DVP, 18', neg. ground, up to 32 frequency, non-weatherproof

 HKN4051A  30" #8 gauge Red Power Cable and Fuse kit (40 amp)
 HKN4052A  Control Head Power Wires and Fuses

 HKN4078A  Light Green 22 pin connector cable kit
 HKN4079A  Light Purple 22 pin connector cable kit, Positive ground
 HKN4080A  Light Purple 22 pin connector cable kit, Negative ground

 HKN4044A  Public Address, Orange 22 pin Connector
 HKN4069A  MDC-600, Green 22 pin Connector
 HKN4145A  MVS-20, Dark Blue 22 pin Connector
 TKN6503A  QC II and Touch-Tone Decoder, Green 22 pin Connector
 TKN6506A  Single Tone Encoder, White 22 pin Connector
 TKN6520A  Voice Privacy Adapter, Red 22 pin Connector
 TKN6731A  Touch-Tone Encoder, Dark Blue 22 pin Connector
 TKN6754A  Siren/PA, Pink 22 pin Connector


Additional Information:

When the Syntor uses a binary code to select the frequency (as is done with the 16 position rotary clamshell control heads), the first channel is coded as a value of 1. For comparison, the Syntor X first mode is coded as a value of 0. Both of these control heads also ground other select lines to tell the radio it is a binary code, but they use different lines to do so (see below).

A Syntor Clamshell control head with the 16 position rotary switch is different from a Syntor X Clamshell control head with the 16 position rotary switch. The white disc with the numbers 1 through 16 is keyed differently and the Syntor X also does not ground the F11 and F12 frequency select lines. Here are the Motorola part numbers for the disc:

36-80148B01 - Syntor $ 7.50
36-80148B02 - Syntor X $ 7.95

The Syntor disc is keyed differently from the Syntor X disc, so the channel selected by the Syntor X 16 position switch does not match the number it displays on a Syntor radio. To fix this problem all you have to do is get the Syntor 36-80148B01 disc, take the Syntor X clamshell apart, swap the new disc for the old one and put it back together. If you are really good at working with plastics I suppose you could reshape the D shaped hole in the center of the Syntor X disc to duplicate the Syntor orientation instead of getting a replacement disc.

In addition, the Syntor X control head will ground frequency select lines F6, F7 and F8. If there is no A/B or R/D switch then frequency select line F5 will also be grounded. These grounds should be removed from inside the control head. If there is an A/B or R/D switch it will be wired backwards (i.e. B/A or D/R). Lastly, frequency select lines F11 and F12 need to be grounded. The Syntor X isolation diodes will not cause any problem for the Syntor.

Because the Syntor has no internal microprocessor control, scanning must be performed directly by the optional scan control head. On the Syntor X, the scan control head only provides information to the radio's internal microprocessor and does not actually perform the scanning. The Syntor and Syntor X scan control heads are not compatible.

Please check out and its Syntor links for more Syntor information.




PL, Private Line, DPL, Digital Private Line, MPL, Talkaround, MDC-600, MDC-1200, MVS-20, Securenet, Smartnet, Privacy Plus, Trunked X2, Trunked X3, Touch Code, Quick Call II, Channel Scan, Talkback Scan, System 90, System 90*s, Systems 9000, Mitrek, Micor, Spectra, MataTrac, Syntor, Syntor X, Syntor X 9000 and Syntor X 9000E are trademarks of Motorola Inc.