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gm300

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rochele1

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hi to all

i have motorola gm300 , on the backside of radio there's something like potential meter , i heard i can increase the power of radio with this , i wanted to ask experts is this true ? i can easily turn it and would have more power ?
my radio is 16 ch

the other question is that on my vhf frequnecy sometimes there's interference how can i detect or resolve this ?

many thanks if you guide me
 

SteveC0625

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hi to all

i have motorola gm300 , on the backside of radio there's something like potential meter , i heard i can increase the power of radio with this , i wanted to ask experts is this true ? i can easily turn it and would have more power ?
my radio is 16 ch

the other question is that on my vhf frequnecy sometimes there's interference how can i detect or resolve this ?

many thanks if you guide me
You will find tons of info on this radio at repeater-builder.com and at batlabs.com

FWIW, I am not sure that is a pot on the heatsink. I'd do a lot of studying of this radio before attempting something like that. And if it is a pot, I'd make darn sure I had the right test gear on hand and connected to the radio, too.

Are you in the US?
 

rochele1

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You will find tons of info on this radio at repeater-builder.com and at batlabs.com

FWIW, I am not sure that is a pot on the heatsink. I'd do a lot of studying of this radio before attempting something like that. And if it is a pot, I'd make darn sure I had the right test gear on hand and connected to the radio, too.

Are you in the US?
thanks , no i'm in Dominican republic
 

kayn1n32008

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Wirelessly posted (Mozilla/5.0 (BlackBerry; U; BlackBerry 9900; en-US) AppleWebKit/534.11+ (KHTML, like Gecko) Version/7.1.0.1047 Mobile Safari/534.11+)

The power output is set in RSS. Be aware though you do not want to push the GM300, they heat up quickly.
 
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MBill

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Can see why you might think it is a power adjust pot. End of the stud has a flat on each side, as if
it was meant for turning. However that is not the case. It is just the stud mount for the transistor.
My guess is that those flats are there to hold the mount so it won't turn when the mounting nut is
tightened down on the PA chassis. Looked at the schematic just to be sure, and no adjustment
pots, etc., shown on the PA circuit.
Any power adjustment is done via the Motorola Radio Service Soft-ware (RSS). The transistor
itself is a MRF2628; Motorola calls it Q2430 on parts list for the VHF model.
As for the interference, is this on receive or transmit? Is it other stations or just noise? I notice
you don't have any TPL on receive. If you are hearing other stations other than those that you
want to hear you can set the 118.8 TPL tone for receive. That will screen out those stations
not transmitting that tone. Note: You must have mike hangup bracket grounded to the radio or
the radio mounting bracket, and the mike in the mike hangup bracket on receive for this to work properly.



h
 

MBill

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Followup post re: mike grounding. You may or may not need to have the bracket grounded to
the radio/radio mount. I believe the GM300 mikes sense that they are in the mounting bracket
and activate the TPL tone screening circuit on receive. You should in any event see the yellow/orange monitor light go out on the GM300 when the mike is placed in its hanger bracket.
 

rochele1

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thanks to all , really helped me alot

about the intereference , i have hanger bracket , sometimes i recieve very bad noise like ggggiiiiiijjjjjjjjjjjjjjjjjjjjjjj

so i asked a technical guy here he told me might be another taxi company is near you , but what i do not understand is that another company has another frequency so what is the cause of this interference , on my gm300 always a yellow led is on .

is there any way that i detect which frequency is this noise from ?
 

cmdrwill

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sniped..t , on my gm300 always a yellow led is on .
First you have to get the 'yellow led' turned off. So you need a Mic that grounds, to the hangup clip, to enable full coded squelch receiver operation.
 
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MBill

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Re: "Mon" led - With radio on, put the mike in the bracket. If the "Mon" led doesn't go off, push and release the "Mon" button, if it still doesn't go out, the internal black ground wire from the metal button on the back of the mike to the circuit board in the mike is most likely broken. Common problem on
used GM300 mikes. Try another GM300 mike if you have one as probably is a problem with mike.
Of course if you are using this as a Ham radio, then you probably don't want to put in a TPL tone
on receive, so that you don't miss any calls. So whether "Mon" light is on or not doesn't make any
difference.
Regarding interference, generally either electrical/electronic or RF. If you can get another
Amateur radio operator to help you that is your best approach. Hard to give help without being
present.
 

ramal121

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RX : CSQ
TX SQUELCH : TPL /118.8 2B

yes HAM
Hey guys, if a RX PL is not programmed, the MON LED will not go out no matter what you do and there is no protection on a CSQ channel except to jack the squelch pot up.
 
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MBill

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Re Mon light. Yes, that's what I initially thought too. But I tried two GM300's without any tones on
Tx/RX, and sure enough when you put the mike in the bracket the Mon light does go out. At least
it does on the VHF model.
Ramal121 your comment about the squelch may be an easy solution to the noise issue. Rochele1
can try increasing the squelch setting; done by the pot marked "SQ" on the top circuit board and see
if it takes away the noise. Clockwise (looking at the pot from the front of the radio) to increase
squelch (less sensitive); counterclockwise to reduce. Could be squelch is at the ragged edge.
 

rochele1

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i really appreciate all you guys , thanks , all the techniques helped and have less interference ,
 

rochele1

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hi All

i have programmed two gm300s for having mdc-1200 , and i have downloaded winmdc (free program for mdc decoder) , when i puch mics of two radios together application cannot recognize and decode but each one of them alone can be decoded , why this happened ? and how can i decode when two radios together send mdc codes ?
 

kayn1n32008

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hi All



i have programmed two gm300s for having mdc-1200 , and i have downloaded winmdc (free program for mdc decoder) , when i puch mics of two radios together application cannot recognize and decode but each one of them alone can be decoded , why this happened ? and how can i decode when two radios together send mdc codes ?

If you mean that they key up and send at the same time... You can not.

The reason for it is called the capture effect, or more specifically, when the signal strength is the same, neither radio will be captured, and the resulting signal at the decoder will be unintelligible and not be decoded.


Sent from my iPad using Tapatalk
 

rochele1

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If you mean that they key up and send at the same time... You can not.

The reason for it is called the capture effect, or more specifically, when the signal strength is the same, neither radio will be captured, and the resulting signal at the decoder will be unintelligible and not be decoded.


Sent from my iPad using Tapatalk
really thanks ,
 
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