GTX 900 Question

[wa3rdm]

I picked up a GTX900 and when I read the codeplug I get
the following model number: M11UGD6CB ... which indicates
it is a 800MHZ radio.

The tag on the radio indicates it is a M11WGD4CB ... a 900 MHZ unit.

Is it possible for these to have been internally changed or do I need
to do something special to get them to go up where they say they will ?

[kcbooboo]

Someone could have blanked and initialized it with the wrong codeplug. I suppose it's possible, but unlikely. If it really is a 900 MHz radio with the wrong codeplug, that should be fixable.

Someone might have swapped main boards and put in an 800 MHz one. They're quite similar.

I'd suggest you remove the top cover, and remove the shield over the power amplifier at the rear of the radio. Three Torx screws hold it in place. Then look at the part number on the blue RF module underneath. The one for 900 MHz is an MHW2821-2. The one for 800 MHz is -1. They're not easy to replace, so it's likely one sure way to figure out what the board is capable of.

I only have a service manual for the 900 MHz GTX; I don't know if there are any other easily visible ways of telling which one you have.

If you pull the main board out, the front end filters might have some identification on them. They'd be 939 MHz for the 900 MHz radio, 860 (or around there) for 800.

Bob M.

[wa3rdm]

Thanks for the info.

If I look and all appears normal, do I just get someone else who
has a current 900 mhz plug and attempt a dump into it ?

It seems I did something similar dumping a low band plug into
a high band MT1000 once to clear it out.

Thanks for the advice , will post how I make out.

[kcbooboo]

Another codeplug is required when initializing a radio, unfortunately. You can't blank it and initialize it from scratch like you can with a MaxTrac. You are given the chance to change the serial number, but that's about it. And of course you need the appropriate program to blank/initialize the radio; we can't utter those magic letters, but let's just say that in octal, they're 114, 101, 102, 040, 122, 123, 123.

Along with a codeplug file, you'd probably need the correct system key file to match it. Then you'll have to go through the complete board replacement procedure, which means aligning the output power, deviation, etc., and having all the test equipment ready for that process.

I suppose there are other radios that make it harder, but this one tops my list.

Bob M.

[wa3rdm]

MHW2821-2

hmm will have to play further...

[wavetar]

I would say it's more likely that someone recased an 800MHz GTX with a junked 900MHz housing they had lying around. Program it for an 800MHz repeater frequency & see if it works, that'll tell you if it's a legit 800MHz board of not.

Todd

[kcbooboo]

The RSS will decide what frequencies can be entered by looking at the model number of the radio. In this case, it'll see M11U and know it's a mobile 800 MHz radio, even if it really is a 900 MHz board. So unless he has a modified program or one that doesn't care what freqs you enter, he'll be forced to put in freqs appropriate for the model number stored in the radio.

I'm holding my ground and saying the board IS a 900 MHz unit, based on the part number on the RF amplifier chip. He could also pull the main board and see if there are any useful markings (part number or frequency) on the front end filters.

I seem to recall someone else had a handheld GTX with a mobile codeplug or model number jammed into it, or vice versa. If that's possible, then I think someone could have blanked the radio (doing the buyer a favor) by feeding it the wrong codeplug.

Bob M.

[train_radio_guy]

I mentioned in an earlier posting, that I had two GTX-900 high power LTR mobiles (M11WRD4CU1_N), with code plug issues. One reads out as a portable GTX-900, while the other reads out as a low power mobile. I may have a kind benefactor, with a source for the proper code plug, but the software 'sees' the model mismatch, and aborts the write to the troubled mobiles. Any idea how to solve this one?

[kcbooboo]

Once you blank the radio with the proper software, you can feed any codeplug into it during initialization. But if it's not blanked first, you'll get the model mismatch and you can't go further.

Bob M.