maxtrac to GM300 repeater

[dmette]

I have two Gm300 hooked up as a cross band repeater it works fine but runs hot..it is used as a link
I was able to get a low power Maxtrac but when They are hooded up I get a delay in the connection
does any one have an idea what is causing this delay the uhf gm300 I can not read the accessory plug
settings it does not come up in the RSS I assume this because of the type of logic board installed
does anyone know the default configuration for this type of radio
Thanks
Dave

[Jim202]

I have two Gm300 hooked up as a cross band repeater it works fine but runs hot..it is used as a link
I was able to get a low power Maxtrac but when They are hooded up I get a delay in the connection
does any one have an idea what is causing this delay the uhf gm300 I can not read the accessory plug
settings it does not come up in the RSS I assume this because of the type of logic board installed
does anyone know the default configuration for this type of radio
Thanks
Dave

The big point here that your finding is that these radios are not made for repeater service. Not only is the heat sink not large enough for the transmitter PA on both of these radios, but the driver stage in the transmitter also lack a large enough heat sink for long duration transmissions.

These radios were designed for only 5 percent TX duty. Then 5 percent RX and 90 percent standby. Going above this duty and your on your own. Even adding fans to try and keep these radios cool won't make them survive for very long.

If your looking for repeater type operation, get a radio that was designed for repeater service. Stop asking the board for ways to make these radios function as a repeater.

Jim

[dmette]

Well I guess if Motorola thought that they would not make the gr 400 repeater
thanks for you response but if you can not be helpfull why bother responding
thanks
Dave

[Satelite]

Hello:
I agree if Jim202 has to have an attitude towards a valid question and issue then shut up.
Yeah I put a little attitude back at jim202.
If you want to be treated with respect try treating others with respect.
Ok back to the postees problem at hand.
Yes Motorola does make the GR300 / 400 and 500 series repeaters.
But many did have the heat issues due to high use transmitting.
Adding a fan will help for a start.
Be aware that these add on fan cooling brackets are available on ebay.
Ok another thing you can do to help with the heat is turn the power down some but if you have a 40 watt pa for example and turn it down too much it will heat up badly too.
So if you take the 40 watt pa for example and turn it down to 25 watts as the minimum youll be at the lowest setting to help with heat and not cause any other issues as im informed from past postings.
Now if you can find the rear pa cooling fin deck from a r1225 I believe it was then youll have the larger cooling finned pa deck that will fit on a gm300 and this will also help with cooling issues.
I have repaired numerous gm300 pa decks that from too long transmitting have gotten so hot that the solder on the finals melted and flowed to other components and shorted out.
But a solder removal cleanup and a higher melting temp solder helped eliminate that issue but didn't do anything for heat .
So yes it is a known fact that the Motorola gm300 was a light duty use radio for repeater use but if you want to you can do the above things to help improve the tx heat issue to make the repeater usable at a higher use demand cycle than originaly specd for.
But id look at possibly adding a rf power amp rated at the wattage youd like and drive it with a 10 watt model mobile with the cooling on both the mobile and rf amplifier as the best cooling option possible as an option too if your inclined to do so.
Do all the above with a 10 watt mobile and add the rf amplifier with cooling fans and you gotter whipped from my experience.
Satelite

[35echo]

Dmette,

I have to agree with Satelite. We help our local Hams the same way by using an R1225 heatsink, turning down power to 25W, and fans. It's NOT 100% duty
cycle but it is far more stable than the stock set-up. The heatsink is NLA from Motorola but they are probably easy to find on the used market. I would try
asking your local dealer if they have any junkers around.

Regards,

Allen

[dmette]

OK thanks to all who replied but the heat thing is not my issue I have fixed that
by running everything low power and cooling improvements.. sorry if I did not make that clear my issue is the delay
between the maxtrac and the gm300 when connecting ..the two gm300 together there is no delay
when I put a gm300 with the maxtrac I get a delay when connecting.. I do not see an option on the gm300 for
accessory pug setting I assume this is because of the type of logic board that is installed..does any one know the
default setting. or what might be causing the delay
Thanks

[Will]

First, we need to know what "connection" between the two radios is.

[dmette]

the two radios are connected by there 16 pin accessory plug
no controller they are configured as a cross band repeater with tow GM300 it works correctly
when I use a maxtrac and a gm300 it works but has a 6 to 10 second delay on passing the signal

[jackhackett]

Hi, welcome to the board.

I think we're going to need a bit more information from you.

First, what are the model numbers of the GM300 and Maxtrac radios you're using?

Now, you say that you are using them as a cross band repeater, and there is a delay passing the signal.

Do you mean that when one radio receives, there is a delay before the other one keys up, or does it key up but there is a delay in the audio being passed, or what?

Also is the delay in both directions, and if not, which radio is the receiving radio when the delay occurs?

Can you give us the connection wiring? For example, this is a wiring from the batlabs site:

Radio1 ------------------------------- Radio2
PIN 3 PTT ___________________ PIN 8 COR
PIN 8 COR ___________________ PIN 3 PTT
PIN 5 TX Audio _______________ PIN 11 Disc Audio
PIN 11 Disc Audio ____________ PIN 5 TX Audio
PIN 7 Gnd ___________________ PIN 7 Gnd

There's a good chance that's how it is, but if you can check it and let us know any differences that would help.

[dmette]

thank you for the reply
Yes that is the way it is wired but I found my issue and have thing
working now.. it was a PL issue
Dave

[tsunami_australia]

Hello:
But id look at possibly adding a rf power amp rated at the wattage youd like and drive it with a 10 watt model mobile with the cooling on both the mobile and rf amplifier as the best cooling option possible as an option too if your inclined to do so.
Do all the above with a 10 watt mobile and add the rf amplifier with cooling fans and you gotter whipped from my experience.
Satelite

This was going to be my suggestion. And I also think Jim needs to eat some humble pie.

I don't unfortunately know enough about the maxtrac to comment on it but for a whilst here ran a 150/480 dual direction link using an M120 for VHF and GM300 for UHF. I had a 90cm fan from a computer power supply (yes was 90 instead of 80 *shrugs*) and had the UHF brick hot-glued to the top of the VHF brick and then that 90mm fan was smack on the right size to be hot-glued to the rear of the pair and give 95%+ coverage of the heatsink on both. With the fan running 100% of the time (was going to install a heat activation but never got around to it) the radios got hot but never skin burn hot like they would without the fans.

[Satelite]

Hello:
I wouldn't take jim202s post too personal because we all have had a bad day then and now.
This isn't normal for jim202 to post as such and he is normaly respectful of others and adds good info.
So he had a bad day = we all do.
That doesn't make him a bad person.
Its water under the bridge and we should just let it go at that.
I sure don't dislike him for it= He just proved hes a human being .
I do $%^#@*( hate computers some days though
Head Shot

[Jim202]

Hello:
I wouldn't take jim202s post too personal because we all have had a bad day then and now.
This isn't normal for jim202 to post as such and he is normaly respectful of others and adds good info.
So he had a bad day = we all do.
That doesn't make him a bad person.
Its water under the bridge and we should just let it go at that.
I sure don't dislike him for it= He just proved hes a human being .
I do $%^#@*( hate computers some days though
Head Shot

I thank you for the support. Yup had a real bad day with some really dumb public safety people. You reach a point where common sense should be the play of the day. But when some dumb public safety know it all tells you how a trunking system will work and you try to explain the facts of radio to them, they don't like hearing it.

I normally am a very patient person and will be a mentor to anyone that asks. But that day was a stone wall. Sorry if I offended anyone, but I am not a saint and do a slow burn at times.

Jim

[tsunami_australia]

But when some dumb public safety know it all tells you how a trunking system will work and you try to explain the facts of radio to them, they don't like hearing it.
Jim

I know that feeling, enough to frustrate anyone. Like the group officers in the fireys telling you there are multiple fires on both sides of the road and when you explain you are weaving around the mountains and it's the same smoke plume. Then that moment when they know more than you regardless of the fact you know the area of the back of your hand. Then the moment after when they won't talk to you because they found out perhaps you do know the area better than them.