Batboard

I have a GTX 800 mhz that is used on a local LTR system. Recently the recieve audio has started cutting in and out randomly. Someone will be talking then all of a sudden it goes quiet, they might come back, it might be a few seconds until I can start hearing again, but I know they are still talking. Every time I have talked to someone on the system, they say my audio on their end is fine. Any suggestions? Im thinking about buying a MTX850 or 8250 but I dont want to dump that kinda cash (at least for the 8250) into it if it is something simple on the GTX, or maybe just buy another GTX.

As a start, go "inside" the radio and check the soldered antenna connection to the board. Does squeezing the case, or bumping it on something, make the problem occur? Also, you could pull the mating circuit boards and reset them; it only takes one bad pin to mess things up. Splitting a GP300 chassis is not for the fainthearted but it can be done if you're careful.

Regards,

Intermittent spkr/mic (accessory) jacks are a common problem on the GTX/GP300/P110 series radio. If you have a spkr/mic, try plugging it in to see if that cures the intermittent. If that's the problem, the jack is not too expensive but there's quite a bit of time involved in changing it. Several components covering the contacts need to be removed before the jack can be changed. I'd recommend Depot but I don't think they support that radio any longer.
Tom DGN

Hello:
If it does by chance turn out to be the accessory jack id try cleaning it with electronic spray cleaner and blow a low pressure air hose into the jacks after doing so.
Again low air pressure = Dont need to blow the jack apart by excessive air pressure.
If no luck then id by pass the audio circuit to go around the jack itself.
Assuming you do not need a speaker mike that is.
Satelite

Tom in D.C. wrote:As a start, go "inside" the radio and check the soldered antenna connection to the board. Does squeezing the case, or bumping it on something, make the problem occur? Also, you could pull the mating circuit boards and reset them; it only takes one bad pin to mess things up. Splitting a GP300 chassis is not for the fainthearted but it can be done if you're careful.

Regards,

Im going to try this first, I forgot to add in the original post, the RX light goes out when this happens, so I dont *think* it would be the audio jack. (been down that road with a GP300 that I have)

On another note, for a 800mhz ltr radio, what do you all suggest?

Looking in my GTX 800 LTR portable repair book .
It says to check Y51A and Y51B filter crystals and also the antenae switch part of the circuit.
But id still check as stated earlier by another to check the antenaes contact inside the radio.
Satelite

Well, I took it apart today, it wasnt as bad as you made it sound Tom, no worse than an astro saber , and the ground antenna connecter wasnt putting good tension on where the antenna connects. I bent it just a bit to give it better tension and re seated the boards. Im going to call a friend and have him give me a test count, or just wait for the wrecker service thats on this system too, to talk, and see what happens. Hopefully that fixes the problem. If not Ill try to replace the filter crystals, and if that doesnt work, buy a new radio.

Any suggestions on another 800mhz ltr portabe?

Knock on wood this seems to have done the trick. I switched to our TG for my work and keyed it, and it didnt do it. Now I just hope it stays that way.

For 800 LTR if you wanna stay with Motorola then go with the MTS-LS. It is basically an 800Mhz HT1000 that does LTR. I have a couple of them, they work great. I actually have an extra if you are looking.

-Justin

As a side note, the GTX series uses a screw-in adaptor for the antenna, and the center pin makes contact with the board through flex fingers.

These springy fingers lose tension, and get oxide buildup on the m over time, which will cause a decrease in signal levels.

Clean this contact, and check the connection to the antenna afterwards for performance issues.

AEC wrote:As a side note, the GTX series uses a screw-in adaptor for the antenna, and the center pin makes contact with the board through flex fingers.

These springy fingers lose tension, and get oxide buildup on the m over time, which will cause a decrease in signal levels.

Clean this contact, and check the connection to the antenna afterwards for performance issues.

Did all this when I took it apart. I believe it is the reference oscilator. I was at our airport, which is well within sight of the tower, and it still did the same thing.

Check that Ref. osc. for freq. stability, and also the 2nd oscillator.

Generate an on-frequency signal and note the level the receiver opens, if at all.
Then tune up and down from that original signal and see where the receiver comes to life if possible.
This will tell you if you have a deaf oscillator in the RX chain, or a bad rock.
Maxtracs had this issue quite often, so I had to stock a quantity of 2nd oscillator crystals for just such issues.

BTW; for all the SP50 users, the crystal used in the 'Tracs are the same as the SP50, just a different 'Y' location, but same part number. (Y52, Y53)