Crossbanding two GM350 radios

[Andresyncro]

Good Day , I need some help

I've got two GM 350 radios ,one a vhf model and the other a UHF model.
I would like to crossband the two radios.
I had a look on the group and found the wiring to crossband the two and connected it up like that, it shows GM300, M120, or M10. I tried doing it that way, But the 2nd radio the UHF radio go into tx immediately.

Is there another way of doing this besides buying a RICK interface. I saw a video on Youtube with two radios connected together with a small board on the aux plug and a interconnecting cable.

Please

Thank You

Andre ZA

[Jim202]

Good Day , I need some help

I've got two GM 350 radios ,one a vhf model and the other a UHF model.
I would like to crossband the two radios.
I had a look on the group and found the wiring to crossband the two and connected it up like that, it shows GM300, M120, or M10. I tried doing it that way, But the 2nd radio the UHF radio go into tx immediately.

Is there another way of doing this besides buying a RICK interface. I saw a video on Youtube with two radios connected together with a small board on the aux plug and a interconnecting cable.

Please

Thank You

Andre ZA

There is more to it than just wiring up 2 radios back to back. Not having a controller of some sort in between the radios to act as the traffic control cop is like asking to drive a vehicle down the road with no brakes.

You need to consider important things like tail on the transmissions. This is needed to at least let the users know they were able to at least get into the repeater.

Don't forget that you also need to have a time out timer. This is needed to prevent accidental lock up of the repeater from a transmitter staying keyed on the input.

Controlling the audio level going into each transmitter is very important. You can't just take the speaker output and stuff it into the other transmitter. Each time you change the volume control, the transmit audio on the other radio will change. This needs to be from a fixed audio source. It probably needs to be from a filtered audio source so your not trying to pass through the CTCSS tone that may be used to open up the receiver. If your using different tones on the 2 radio receivers, this could cause problems on the transmit side if your also injecting a different CTCSS tone. Need to think this through carefully.

You didn't say if this back to back radio package was to be able to repeat in both directions or just in one direction. Need to know this before you try to put the electronics together.

If the plan is to use this as an emergency fill in package, what are you going to use for a power source? What are you going to use for antennas on the 2 radios? How are you going to support the antennas? How are you going to weather proof the package?

The location of this radio package really needs to be known. Is it going to be placed at a tower site where there are other radios in the same band as your planning to put these radios? You have to take into consideration that using a radio not designed for a high RF environment could cause you all sorts of receiver problems. Probably would require you to put pass band cavities on both radios.

Not trying to put the brakes on your efforts, but there is a whole bunch of planning that needs to go into putting a repeater package together. Some planning up front will pay off big time in the end.

OK, I have passed along some thoughts for you to consider. Let the group know how you proceed and what you did to put you idea together. Others can learn from your efforts.

[SteveC0625]

Check out the repeater cables offered by ebay seller mre1032 - he has an excellent rep with many members here and on other radio forums for his Motorola cables and parts kits. He includes detailed instructions with each repeater cable including programming guidance, and offers several different versions that are /\/\ specific to meet different needs.

Coupled with the great information that Jim202 just gave you, you should be able to get your crossband unit up and running properly and fairly easily in a short period of time

[Andresyncro]

Hi Guys and thank you for the valuable advice,


I have ordered the cable as advised, Being in South Africa I suppose it will take a few weeks to get here.The crossbanding is to reach another vhf repeater that is not accessible to the guys living near to it. The people live right under the mountain and due to the waterfall effect can not access the repeater. As soon as I've got the Crossband sorted out I will give them UHF equipment to use. In other words UHF TX-->UHF RX + VHF TX to VHF Repeater and same in return. Ive tested the setup with a set of Baofeng radio's set up as crossband repeater and it works. The duty cycle of a small 4 w Talkie does not suit me. Antennas is a VHF omni ans well as UHF Omni stacked about 3 Metres on top of each other.Radio output is also 25 W on the UHF TX .On the VHF 5 Watt . The distance to cover is about 3 km . Weatherproofing is a descent case with cooling etc. Batteries is 102 AH 12V with Hawkins Smart 15 industrial smart chargerrunning from 220V. The site for the crossband is about 40 meters high on top of a building. Earthing is sufficient. How can I send a KMZ file to someone ?

Thank You again

Andre

[Jim202]

Hi Guys and thank you for the valuable advice,


I have ordered the cable as advised, Being in South Africa I suppose it will take a few weeks to get here.The crossbanding is to reach another vhf repeater that is not accessible to the guys living near to it. The people live right under the mountain and due to the waterfall effect can not access the repeater. As soon as I've got the Crossband sorted out I will give them UHF equipment to use. In other words UHF TX-->UHF RX + VHF TX to VHF Repeater and same in return. Ive tested the setup with a set of Baofeng radio's set up as crossband repeater and it works. The duty cycle of a small 4 w Talkie does not suit me. Antennas is a VHF omni ans well as UHF Omni stacked about 3 Metres on top of each other.Radio output is also 25 W on the UHF TX .On the VHF 5 Watt . The distance to cover is about 3 km . Weatherproofing is a descent case with cooling etc. Batteries is 102 AH 12V with Hawkins Smart 15 industrial smart chargerrunning from 220V. The site for the crossband is about 40 meters high on top of a building. Earthing is sufficient. How can I send a KMZ file to someone ?

Thank You again

Andre

Sorry for asking so many question. Sounds like you have this well in hand.

Jim