- CANADIAN SYNTOR X
		- Introduction
		- Basic Information
			- HLN4240A Common Circuits Board Controls
		- Custom Changes
			- HLN4257A Missing Component Locator
		- PA Power Adjustments
		- Future Projects
	- Syntor X Home
	- HOME

Introduction:

This page is not included in the normal navigation menus and is normally only accessed from the Syntor X home page.

This page is specifically about two 30 watt, programmable dual output power, VHF range 1 (136-154.4 MHz), Syntor X VHF radios I got from Spantek Radio Ltd. in Canada. This is not an advertisement, it is information about the radios and the modification I had to undo to make them work correctly.

The radios model numbers are marked T33VBJ3204-MFY and the unified chassis numbers are YUD1011A. They came with a mounting tray and no accessories. I bought them untested and they both work just fine after I restored a missing part (see below). The programmable high/low RF output power works also. Probably the most common Syntor X radio today is the VHF range 2 (150-174 MHz), so it was a real treat to find some hard to locate VHF range 1 radios.

Both radios arrived set to 40 watts output power so I turned it back down and set them up as 30/15 watt radios. The low power setting is programmed into the code plug of any individual mode (normally this only applies to T83VBJ and T53VBJ radios). So far they are working out as great HAM radios.

The Personality Board and Common Circuits Board are the ones normally found in range 2 T83VBJ and T53VBJ VHF higher power radios. The SP02 on the Common Circuits Board part number indicates this board was factory modified for range 1 and the lower PA power. One of the radios has a HLN4240A1 Common Circuits Board and it also works. Service manuals for both T43VBJ (68P81060E05-C) and T83VBJ (68P81060E05-O) radios are required for this radio. The Personality Board and common circuits board documentation are located in the T83VBJ manual. Everything else is in the T43VBJ manual (the -C revision is required for range 1). Up until now I had never seen a T33VBJ model number.

Electronics soldering skills and equipment will be required to restore these radios to normal operation.

Basic Information:

Unified Chassis - YUD1011A similar to HUD1497A + programmable dual RF PA Power Range

HLN4257B1 - Personality Board

One- HLN4240ASP02 - Common Circuits Board with dual level programmable P.A. power control
One - HLN4240A1 - Common Circuits Board with dual level programmable P.A. power control
Click this link for the control layout of the common circuits board.

HLN4491A - Range 1 Rx Pre-Selector Filter

HLD4133A - Range 1 VCO

HLD1071A - Range 1 Internal Casting

HLN4492A - Range 1 RF Board

HLD4134A - Range 1 30 watt RF Power Amplifier (PA)

They came with jumpers 1,2,3,4,5 installed, 7 is not used, 6 and 8 are not installed. My control head setup required removing jumper 1 (Scan Enable) because I have a Scan Enable switch on my control head ("PRI" button). I installed JU8.

Custom Changes:

This section is about changes to the HLN4257B1 Personality Board. The following three jumpers were found on the solder side of the board where the J1 main radio connector body is located.

J1-8 (SW B-) to Ground
J1-B (A-) to Ground
J1-5 (PTT Ref) to J1-15 (SW B+)

None of the jumpers should cause any problem for a "standard" negative ground setup, but they are not needed. If you use a positive ground installation these jumpers will cause fuses will blow and sparks may fly. I removed the above jumpers from my radio. If you remove yours by unsoldering them (like I did), you should watch out for excess melted solder dripping from the ground connection where two of the above jumpers are soldered together at ground.

Changes to the top of the HLN4257B1 Personality Board. The following three long jumper wires were found and the following diode was missing:

J1-36 to J441-1 - Audio Mute Override (CR440 removed, Priority Sample Mute control)
J1-34 to J442-1 - Audio Monitor Enable
J1-35 to J443-2 - Sidetone In

CR440 removed
Click this link to see the parts locator for the missing diode.

Headers were installed for these wires to plug into (headers are the little prongs coming up from the circuit board). The jumper wires were intended to override the radios ability to mute the audio amplifier and also inject an audio sidetone signal into the audio amplifier (using cable pins J1-34, J1-35 and J1-36). I do know what the accessory was that needed to do this to the radio. I removed the 3 jumper wires (they just unplug). Then I plugged a wire into the header pin located on JU8 into J442-2 (ground) to install an unconventional JU8 (installing JU8 is optional).

The way the radio was modified, the external accessory hardware was the only thing that could completely mute the audio using J1-36 as a control line. Removing CR440 made it impossible for the radio's internal microprocessor to completely mute the audio. For normal use, with CR440 missing there will always be an annoying low level hiss in the radio's speaker when there is no signal coming into the receiver. CR440 is a common silicon signal diode. Just for expedience I unsoldered and removed CR441 (next to CR440) and reinstalled it as CR440. The diagnostic jumper J441 (Audio Mute Override) will not function until CR441 is replaced, but the radio's audio now mutes correctly for normal operation. The banded side of diodes CR440, CR441 and CR442 are all oriented exactly the same direction on the board. All of these diodes are mounted standing up on the circuit board as the solder pads are too close together for the diodes to lay flat on the board.

Since I did the modification above (moving CR441 to CR440), I found a bunch of silicon general purpose signal diodes in my parts bin. One of them worked on the second radio as a direct replacement for CR440. There is nothing special about these diodes. Just make sure you do not use speciality diodes (i.e. zener, hot carrier, tunnel, etc.) or germanium diodes. The replacement diodes should also be about the same physical size as the existing diodes (CR441 and CR442). If you can not locate a source for diodes then just move CR441 to CR440 and remember that J441 (Audio Mute Override) will not function correctly if you ever have a reason to use the J441 diagnostic jumper.

If you insist on the real Motorola Parts here is the order information, however, you will probably have to make a bigger order than 43 cents (U.S.) total:

Diodes CR440 - CR445 Motorola New Parts Ordering Information
Part #	Description	Quantity - Price
48-11034A01	DIODE 48C83654H01 A/I	5/package - 43 cents

When looking for these parts keep in mind that one edge of the Personality Board is covered by the chassis, RF board and Internal Casting (i.e. if you wanted to get a good look at U9 you would need to remove the Personality Board from the radio). JU4 can be located with a flashlight and some patience.

The Motorola 68P81060E05-O manual shows R450 and R451 in the wrong positions in the HLN4257A Personality Board details drawing (Microcomputer System, page 11).

PA Power Adjustments:

The potentiometers in the HLN4240A1 - Common Circuits Board could not be adjusted from the back with the board screwed in place (there is no access hole in the top for the PA low power set). The board had to be hinged open and up to set the PA low power level. Unscrewing the fasteners and hinging this board up deprives the power regulator heat sinks of contact with the chassis, so it should not be run in this position for extended periods of time and be careful not to burn your fingers. The HLN4240ASP02 - Common Circuits Board PA low power level potentiometer could be adjusted from the back with a very small tip tuning tool.

Remember, the code plug has to be programmed for PA low power (EEPROM mode byte 8, bit 2) and a mode with PA low power must be selected before you can adjust the PA low power potentiometer. Do not adjust the PA low power setting below 15 watts unless you have a RF spectrum analyzer and can confirm the PA output does not develop spurious emissions.

Of course the PA output power is rated to operate within +-20 % of its rated power. So you could actually stretch 30 watts into 36 watts maximum and still be within specification, but it is such a small difference in the signal strength I never bother doing it. If you have a really long coax run to the antenna, bumping the power (within specification) can help make up for the losses. If your antenna has a high VSWR, the radio's automatic protection circuit may already be turning down the PA power. So adjusting the power upwards to compensate will not help, with the exception that it might help shorten the life span of the radio's PA.

Future Projects:

The internal casting, Personality Board, Common Circuits Board and RF board can all be exchanged into a 100 or 110 watt VHF chassis. This would make a 100/50 or 110/55 watt range 1 radio.

The headers that were installed for the jumper wires make custom data path connections very easy. This will be an ideal radio to finish the packet hookup exploration with.

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