MAXTRAC/GM300 out of band questions

[KB2ZTX]

So i read over the site last night. I have a box of now non usable maxtrac and gm300 VHF 146-174 Mhz mobile radios that we removed from our SAR vehicles. We have used this for some time in the 146 ham band in addition to our SASR channels. As we also run a APRS packet system and adding more devises Id like to use some of these for that vs the dumpster. My question is has anyone gotten them down to the 144 Mhz area. I really dont want to go the route of swapping RF boards, blanking the logic and all that, but if i can tweak the current board without many headaches to get to this frequency Id be happy. If its too much work they will make it to the used market but trying to recycle some of our gear.

[N4KVE]

Very easy to do. When you want to enter the 144 freq's, instead of using the numerical buttons at the right of the keypad, hold the shift button while entering the freq using the numerical buttons above the QWERTY buttons. The screen might say the freq's are out of the bandsplit, but ignore this message & keep going. This is called the "shift" method, & works fine. GARY

[KB2ZTX]

Thanks familiar with the shift method, just didn't know if the hardware would support it that low. Guess i'll try it tonight.

[n7maq]

Keep in mind there is NO power control below 146.00Mhz on a high split Maxtrac, I don't know about the GM300 but I bet it is the same. You will need to address that or you will kill your PA in a short time.

Jim

[fnuus]

I try to use the SHIFT button to, i get on the display strange symbols, but that is ok. But when i enter a frequency ( 153.15600) with the SHIFT button then i see on the screen the frequency 153.15625. Is this then OK ?

Fred

[fnuus]

I try to use the Alt Button to program a Frequency ( 153.15600 ). I get when i use the Alt-button strange symbols, that's normal. But then he change the frequency in 153.15625 on the screen.

Is this normal ?

When i write the data to the GM300 is he then programming the 156.15600 or 153.15625 ?

Fred

[Satelite]

Hello:
Ok ill try to answer your question from how I understood it.
If you enter on a maxtrac the freq of 153.15625 you don't use the shift key method as the 153 is in the maxtracs band spread.
But the maxtrac is wide band only so its only going to do 153.156 part but actualy .155 as the freq jump in the maxtracs rf bd only does 5 jumps not a 6.
Hope I said that right so youd understand .
Now the 153.15625 is taking the freq even further than the maxtrac was designed to do but with some retuning ect you might get it pretty close.(But again the Maxtrac is 25khz wideband so wont work as it should per USA fcc rules and not legal)
But the maxtrac is legal for ham use .
Ok you mentioned the GM300 as you tried to enter 153.15600 but when you enter it the program changes it back to 153.15625 and that's because the radio doesn't recognize the first because you didn't jump freq by 25 or 5 per radios specs and during programming it actualy programmed to 153.15625 because it fits the radios freq jumps which 153.15600 does not because its neigther a 25 kHz or 12.5 narrowband jump.
However I do think you can do it with the shift key method and ill set an example so you see it here on the screen.
So for example from 153.0000 you can add or subtract 12.5 or 25.0 kHz and the radio would accept it as an entry since that's what its freq jumps are.
Ok with the freq of 153.15625 you hold the shift key down and don't let up on any numbers with the exception of the decimal point you don't use the shift key.
So 153.15625 in shift key with the decimal not shift keyed itll look like this !%#.!%^@%
Ok notice that the period or decimal is as it should look like and not > if you used the shift key so don't use the shift key for the decimal point or period if you want to call it that so itll look like this .
Ok be aware that the maxtrac was made 25khz wideband only and that the GM300 was made wideband and also narrow band both.
Now the freq that your posting tells me your trying to program a narrow band freq of what we call 12.5 narrow band .
So yes you can put it in the wideband gm300 but it will tx and rx at 25 kHz wideband causing you to hear and tx out of the desired freq programming your looking for.
Not to mention illegal operation but ill stop with that as its info so your aware of it if your in the United States of America. ( Not sure on other countries rules ect )
Hope I helped rather than confused you more.
But bring on the questions we got answers.
Satelite