Using some GP300's or old Genesis radios as crossband repeaters

[Golay]

I'm going to put this query here. Figure about the best place for it.
I've accumulated a slew of GP300's, HT600's and P200's. Both VHF and UHF. And plenty of beat up mikes for each.
Thinking about hooking a couple together to crossband repeat. Want to get into our local repeater which is at a lower elevation for awhile.
It will just be two radios. I can hear the repeater fine, just a bit of bacon getting into it.
Like I said, I got mikes, which I can use the cables to cut up and splice together and connect a VHF and a UHF radio together.

Is there a fairly inexpensive way to have what one radio hears, transmit on the other?
Like I said, it will be two different bands so I shouldn't get any desensing, right?
Thanks for any replies. Just kind of a thought for something to do with these radios, other than the closest dumpster.

 

[MTS2000des]

You'd be better off using a "for real" crossband capable dual band ham mobile like a TM-V71A, or a plethora of other models, that can withstand the duty cycle of being a crossband repeater (when run at low/mid power). Portable radios aren't designed to be keyed down for long periods of time, and you'll need to fashion a proper 7.5 (GP300) or 10.1v (HT600/P200) regulated power supply, a COS/COR circuit, CW IDer, etc.

You'll have a lot more fun with a "for real" dual bander too. The V71A can be fully DTMF remote controlled from your HT.

 

[a417]

totally possible, and the same time...totally impractical. portables are designed for the "5/5/90" duty cycle (5% TX, 5% RX, 90% standby) which we all know is ridiculous the way some people talk, and have almost no considerations for cooling. You will spend more time meeting the requirements like MTS2000des posted above, and less time using them.

I'd part them out for repair, someone might be looking for PAs or key assemblies or chassis or something.

 

[kayn1n32008]

I'm going to put this query here. Figure about the best place for it.
I've accumulated a slew of GP300's, HT600's and P200's. Both VHF and UHF. And plenty of beat up mikes for each.
Thinking about hooking a couple together to crossband repeat. Want to get into our local repeater which is at a lower elevation for awhile.
It will just be two radios. I can hear the repeater fine, just a bit of bacon getting into it.
Like I said, I got mikes, which I can use the cables to cut up and splice together and connect a VHF and a UHF radio together.

Is there a fairly inexpensive way to have what one radio hears, transmit on the other?
Like I said, it will be two different bands so I shouldn't get any desensing, right?
Thanks for any replies. Just kind of a thought for something to do with these radios, other than the closest dumpster.

I would use a GP300 as a receiver, and a TK-x180 or NX-x00 25w mobile, set to low power, and the transmitter.(ASSuming its
I’m sure there is a service manual out there for the GP-300, where you can pull flat audio out of it, and inject it into the mobile. You can get an RF adaptor for the GP-300, or solder a coax jumper directly to the receiver.

The GP-300 has an excellent receiver.

 

[Golay]

OK. Thank you anyway.
There really wouldn't be much duty cycle involved. It would only be transmitting when I transmit.
I'm not thinking of listening to a repeater thru it.
Thanks for the replies.

 

[kayn1n32008]

OK. Thank you anyway.
There really wouldn't be much duty cycle involved. It would only be transmitting when I transmit.
I'm not thinking of listening to a repeater thru it.
Thanks for the replies.

Then I would strip the cases off of two GP-300’s, and follow the audio chains and find flat audio for this project. I would avoid using the speaker mic plugs to do this.

 

[bill4long]

Is there a fairly inexpensive way to have what one radio hears, transmit on the other?
Like I said, it will be two different bands so I shouldn't get any desensing, right?

No problem on the desense. If you are going to use the same antenna, get diplexer for about $50 new. As for control, it's very easy to throw together an interface using a transitor and a few other components. But you can build an Allstar based node with simple cross band, or up to full repeater control for about $100, which is a Raspberry Pi and a URI control interface. The duty cycle of a GM-300 (which is the radios GP-300 are actually using) can run fully duty if you attach a 4x4 inch CPU fan on it. People on Allstar do it all the time. Use a 25w radio and not a 40w radio if you can.

 

[bill4long]

You'll have a lot more fun with a "for real" dual bander too. The V71A can be fully DTMF remote controlled from your HT.

$380 brand new. I have one, and no doubt they are gooders. I also have a Yaesu 8800 which has served me well for cross band. I think the crossed audio sounds better on the Yaesu, but it doesn't have an IDer. (There's a legal way to deal with that.) I have also put together several repeaters, crossband, and remote bases using various radios, and GM-300 works well. I recommend Allstar-based setup using Rasp-Pi and URI as a controller these days if one doesn't already have one.

 

[kayn1n32008]

$380 brand new. I have one, and no doubt they are gooders. I also have a Yaesu 8800 which has served me well for cross band. I think the crossed audio sounds better on the Yaesu, but it doesn't have an IDer. (There's a legal way to deal with that.) I have also put together several repeaters, crossband, and remote bases using various radios, and GM-300 works well. I recommend Allstar-based setup using Rasp-Pi and URI as a controller these days if one doesn't already have one.

The TM-V71a is FAR superior to the FT-8800 with respect to crossband repeat. It is one of the reasons I sold my FT-8800 and bought a TM-V71A to replace it.

 

[cmdrwill]

A little trivia Motorola did make a repeater that had two GP 300 chassis with the transmitting GP300 heatsinked.

 

[bill4long]

The TM-V71a is FAR superior to the FT-8800 with respect to crossband repeat. It is one of the reasons I sold my FT-8800 and bought a TM-V71A to replace it.

The V71 has more functions. But none I would consider essential in my case. I wouldn't say it's far superior. I like the crossbanded audio better on the Yaesu. . 8800 is no longer in production. 8900 still is, however, and it has 10 and 6 meters, and can crossband using those bands from 2m and 440 as well. Something the V71 doesn't do. Whatever works for ya.