Motorola Syntor X Model Identification

[Twitch]

I have this Motorola Syntor X T73VBJ04BK and I woul dlike to know if it will accept 136-144Mhz frequencies.

I have looked up the models list for Syntor X on
http://www.open.org/~blenderm/syntorx/m ... ml#sxc3mod

but I can't find the exact model, the closest I have is T73VBJ7J04AK 150-174 MHz, 100 Watt, 32 mode.

The model number written on mine is T73VBJ04BK.

Can anyone help me finding the correct specifications for this Motorola Syntor X T73VBJ04BK I have?

[DPL]

I don't know 100% that this is the case for Syntor X radios, but on most Motorolas the 2nd digit from the right is the firmware version. "A" being the first, "B" being the second, etc...

If this is the case, it means that your radio has the second version of firmware. This should not have any effect on the bandsplit.

As far as accepting 136-144MHz frequencies, I'm not sure. I believe that the Syntor X radios are pretty forgiving about going outside of their official bandsplit, and I think that it will work on the ham band without problems, but I don't know how low it will go.

[Mike B]

I don't know 100% that this is the case for Syntor X radios, but on most Motorolas the 2nd digit from the right is the firmware version. "A" being the first, "B" being the second, etc...

Actually, its not the firmware revision, its a major manufacturing revision for the entire radio hardware package. You will typically find newer part numbers on the printed circuit boards of later revision radios like the 'B'. In the Syntor X you have to look at the microprocessor part number code for firmware information (there is not much info on this firmware anyway):
http://www.open.org/~blenderm/syntorx/perbdx.html#peru8

The only way to tell the factory band split is the chassis number, maybe the factory programming sheet frequencies in the top lid (only if it matches the radio serial number) or by looking up the individual assembly part numbers on the VCO, PA, etc., driver circuit boards.
http://www.open.org/~blenderm/syntorx/vtourvx.html#ucn

If you look at:
http://www.open.org/~blenderm/syntorx/m ... ml#sxc3mod
again, notice that each group of model numbers has a section of chassis numbers under it. The high power T73 models all have 150-174 MHz (range 2) factory band splits. Its only some of the medium power T43 radios that have a 136-154.4 MHz (range 1) factory band split. These VHF range 1 band split radios can be hard to find and make sure you check too make sure its really a range 1 before buying the wrong range radio.

You could make your own T73... 136-154.4 MHz (range 1) band split by taking the guts from a low split T43 range 1 radio drawer and putting them into a T73 radio drawer as replacements (except for the high power PA deck of course). You would have have to readjust all the Common Circuits board adjustments, but the VCO, pre-selector and injection filters will already have the correct factory range 1 tuning.

Here are the VHF manual number identifiers for the various VHF radios:
http://www.open.org/~blenderm/syntorx/m ... ml#xvhfloc
You can see the 68P81060E05-C revision manual is the only one with specific information on the 136-154.4 MHz range 1 band split radio circuit boards and part numbers.

You could also re-tune a stock T73 to lower its frequency coverage, but it will be difficult if you want to go all the way down to 136 MHz. This type of retuning is much easier when you just change the coverage to start at 144 MHz for HAM radio work.
http://www.open.org/~blenderm/syntorx/efreqx.html
http://www.open.org/~blenderm/syntorx/e ... tml#ef_adj

[WB6NVH]

I am pretty sure I have a Range 1 T73 series radio which came from the factory that way, for the federal government. I'll have to check and compare numbers. It was in service on a bunch of 140 MHz channels.

If you want to use the radio on the ham band, and still have commercial coverage, you'll need to retune the receiver front end and injection deck to move it down about 6 MHz. This isn't trivial but Bruce of Blue Feather Tech, who visits these forums regularly, can do it for you for a nominal fee. The VCO may or may not lock, down at 144. The data on how to change the VCO range if necessary is on the various websites. After the conversion the range of the radio becomes something like 144-160.

[George]

What will tell the story really quickly is looking at the P/N of the power amp.


Is it an HLD-4376?

George

[Mike B]

I am pretty sure I have a Range 1 T73 series radio which came from the factory that way, for the federal government.

I have never found any factory documentation on a T73... range 1 radio drawer. Are you sure it was not a special product that had SP with a 2 digit number appended to the end of the model number (sometimes just the chassis number tag)? To be clear, SP radios were direct from the factory, but they were not available as standard order one off the shelf products. SP radios usually had their own supplemental documentation (occasionally even a full manual) which are mostly long lost and gone before the radio gets surplussed.

I would like to know if there is a chance of finding any factory non-SP range 1 high power radios. Currently I ignore all standard product T73... radios when looking for a VHF range 1 (i.e. I only look for T43... radios).

[WB6NVH]

Well, I went out and pulled the drawer off the shelf and here's what it is:

T73VXJ7J04BK with no SP suffix, just a standard nameplate, which I think is the early style (blue lettering on an aluminum plate as opposed to the foil "decal" kind.)

The paper tag printed by the factory and stuck inside the lid has a bunch of 136 and 140 MHz channels listed (This was used by the Navy.) The serial number and model number of the radio, as listed on that tag, match the model number plate and there's no question it's numbered T73.

The transmitter PA is YLD4005A, the receiver filter/helical resonator casting is HLD1614A. The HUD number on the paper sticker on the frame is somewhat water damaged but it looks like it says HUD1026A.

I haven't checked it on the bench yet because I would have to burn a new code plug first (plug was missing when I got it.)

I had always assumed it was a T43 and was surprised to discover one day that the # was actually a 73.

[Mike B]

Sometimes YLD parts are SP modified, but not always. The VHF Syntor X documentation I have uses HLD4... numbers for the internal casting part numbers. I could not locate that chassis number.

Did you check the serial number from the radio lid programming sheet? It must match the radio's serial number if it means anything. The radio drawer lids are interchangeable and often get mixed up in surplus radios. Anyway, with the strange part numbers you found I suspect you did already check the serial number.

Thanks for opening my eyes to other possible sources for range 1 radios. BTW, you can convert it into a Syntor X 9000 if you want to upgrade:
http://www.open.org/~blenderm/syntorx9k ... xto9k.html

I have a range 1 Syntor X 9000 with the optional range 1 Rx preamp. It appears to be the most sensitive VHF receiver I have. It still hears a very scratchy 1 KHz modulated tone all the way down to where my old service monitor generator cuts out (lower than .09 microvolts).

[WB6NVH]

Yes, the lid tag matches the serial number and model of the radio.

As far as I can tell, the only Y-prefixed board is the PA. I didn't take the VCO cover off to look at that but I presume that would be a standard # for a range 1 VCO.

I forgot to check whether there was a preamp on the RX.

There weren't any accessories with it when I got it but it has a standard configuration on the personality board (i.e. not a HHCH setup.)

That was my idea too, to convert it to an X9000 eventually...