Batboard

Since it is nearly impossible to find a (Hi pwr) Lo-split UHF Syntor-X (or Syntor or X9000 or Maratrac or Spectra or ...) while Hi split radios are common and lo-priced, I wander if it is feasible to turn a Hi split radio into a Lo split (407-417 region).
I'm sure i can fix the VCO, but what about the PA or the rx front-end?

Spectra range 1 are easy to find here in the US (at least they were a few years ago). The problem with the Spectra is you have to read the radio to know the split or see if it has a FCC identifier of AZ492FT4779 (there are other FCC identifiers that are not unique to just the low split). I wouldn't buy any Spectra UHF unless the seller knows the exact split. Quite a few of the UHF low split Spectra radios I have seen are high power. The range 2 is the one HAM radio operators want. There are probably lots of HAMs that purchased range 1 low splits and were angry when they found out it was way too much work to convert them. In fact, as far as I know there is hardly any market for low split UHF Spectra radios here in the US.

The problem with a Syntor X or Syntor X 9000 UHF range 1 (406-420 MHz) is it used high side injection VCO (Rx frequency + 53.9 MHz IF frequency) while the range 2 (450-470 MHz) and above all used a low side injection VCO (Rx frequency – 53.9 MHz IF frequency). A range 2 would be the best choice to convert to a range 1 (still using low side injection), but it would be one heck of a job. It's just too big of a frequency shift to do without fairly massive component replacement/tweaking.

Don't forget about the Syntor X 9000E. They made a low split UHF version of this radio. All you have to do to convert the 9000E to conventional 9000 is remove the plug-in trunking controller board and change out the U501 firmware EEPROM for a conventional one. Its more of a challenge to get the X9k conventional RSS to program a trunking head back to conventional. Watch out, there are also UHF range 2 and 800 MHz 9000E radios.

http://www.onfreq.com/syntorx/syntorx9k/controlx9.html

Finding and purchasing a UHF low split would be much easier than attempting a conversion. If these are not available where you are, I suspect you will have to pay some astronomical shipping fees to get one.

I will keep my eyes open... I thought that the 9000E was only a 800 MHz model.
I check ebay regularly but I could locate only 45W spectras in range 1.
Oh, about the shipping cost, I am well prepared to take the punch! The problem is that most sellers don't ship out of ConUS, so I have to ask some US-based friends to forward to me.

I spent some time looking for UHF range 3/4/5 Syntor X'en, on the theory that I might be able to use them with the transmit/receive ranges programmed backwards to get a radio in the low 430s. We had first tried to retune a range 1, and couldn't get it to go that high. Never did find any of the 3/4/5s.

De