Spectra Remote 800mhz to maxtrac 16 pin

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dfc2
Posts: 360
Joined: Sun Mar 10, 2002 4:00 pm

Spectra Remote 800mhz to maxtrac 16 pin

Post by dfc2 »

Is there a cable or box out there to connect a remote spectra ( on an 800 trunked system) to a maxtrax on a simples or semi duplex 800 freq? I work in a small village and we have one spot over the hill where our portable s DONt work at all... make us go back to the car to get out.... problem is the reason we are there is the resident like to fight the police... so not having radio out of the car is a no no... but nothing I can fix by throwing money at it... council says no money....



So.. My hope was to use our current Spectra's on our normal 800 trunked freq, patch in a maxtrack with one of our authirized simplex car to car freq's possibly with the maxtrac antenna mounted at the front of the car, and the spectra's antenna at its normal place on the trunk to get some seporation. i;ll have to look for a cheep duplexer and see if thats do able.. otherwise,,, would the 45 mhz split in the trans and receiv freq be enough to allow the system to work without de sencing each radio?


Anyone have some inpute?


DFC2
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Josh
Posts: 1931
Joined: Mon Sep 03, 2001 4:00 pm
What radios do you own?: APX4K, XTL5K, NX5200, NX700HK

Re: Spectra Remote 800mhz to maxtrac 16 pin

Post by Josh »

dfc2 wrote:Is there a cable or box out there to connect a remote spectra ( on an 800 trunked system) to a maxtrax on a simples or semi duplex 800 freq? I work in a small village and we have one spot over the hill where our portable s DONt work at all... make us go back to the car to get out.... problem is the reason we are there is the resident like to fight the police... so not having radio out of the car is a no no... but nothing I can fix by throwing money at it... council says no money....



So.. My hope was to use our current Spectra's on our normal 800 trunked freq, patch in a maxtrack with one of our authirized simplex car to car freq's possibly with the maxtrac antenna mounted at the front of the car, and the spectra's antenna at its normal place on the trunk to get some seporation. i;ll have to look for a cheep duplexer and see if thats do able.. otherwise,,, would the 45 mhz split in the trans and receiv freq be enough to allow the system to work without de sencing each radio?


Anyone have some inpute?


DFC2
Depending on how many cars you have, you may want to look into a VRS, vehicular repeater system. It would require the officers to carry a portable radio on a different frequency range when in the area, but signal would be relayed through the car's mobile radio to the portable. I use 'em all the time.
dfc2
Posts: 360
Joined: Sun Mar 10, 2002 4:00 pm

Re: Spectra Remote 800mhz to maxtrac 16 pin

Post by dfc2 »

I thought of that. We only have 2 cars. very seldom are both on scene. the cost of a VRS is far more than picking up 2 spectras or maxtracs.

DFC2
dfc2
Posts: 360
Joined: Sun Mar 10, 2002 4:00 pm

Re: Spectra Remote 800mhz to maxtrac 16 pin

Post by dfc2 »

carrying a second portable is not an option. Im not going to have officers carrying two radios. the problem is only in one area.. but they are there often enough that I need to solve the problem. I have asked for funds to go the VRS route.. but the authority to approve purchases and the common sence to approve it when if is really needed do not go hand in hand. the short story is... I can try to pay a few hundred to solve the problem out of my own pocket or I have to wait till somone gets hurt to change minds in council.... which would you do?
DFC2
akardam
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Joined: Thu Mar 04, 2004 10:53 am

Re: Spectra Remote 800mhz to maxtrac 16 pin

Post by akardam »

Two problems:

1) If you're trying to do this in-band, you're going to need some mondo serious RF filtering/isolation equipment so ensure that the two radios don't interfere with each other. You'd probably end up talking about more $$ to do that than to buy another radio + a VRS, and even then there's no guaruntee that you wouldn't have to deal with desense and intermod.

2) Unlike purpose build VRS's, a maxtrac back to back with a spectra has no way to let the remote radio user know that he's got a valid channel grant on the TRS.

In short, this is a life/officer safety issue. A mickey mouse solution is not the right answer.
dfc2
Posts: 360
Joined: Sun Mar 10, 2002 4:00 pm

Re: Spectra Remote 800mhz to maxtrac 16 pin

Post by dfc2 »

As I stated in the prior post. There is NO money to pay for it. I am trying to figure out "Some Chance"... which is better than "NO" chance.

Maxtracs are $100.00, Spectra's are $200.00, a VRS is $1500.00 or better... I , meaning personally my own pocket can't afford to pay that...... for a VRS... forgive me for trying to come up with some solution. the simple fact is... the people who control the money don't care until it costs them personally...I don't want it to go that far. I made it clear in the first post. If you have another option, feel free to pass it on.

If I have to I will put this set up at the station, close enough to use from the bad part of town, and enough room to put 50-100 feet between the transmit and receive antenna's..... prefer it in the car, but the station is anothe roption.

So far I am not convinced that it can't be done..... as far as knowing if the trunked radio has a channel, a short press on the radio, then listed for the talk group to key up, should do that....

the desence may be solved by putting the antennas as far apart as possible, plus the difference between the transmit and receive freq ( 45 Mhz I think).... I could be way off base here.. but I am asking for imput from somone who has tried, or deal with this.

Am I wrong to try and come up with a solution?


DFC2
akardam
Posts: 2251
Joined: Thu Mar 04, 2004 10:53 am

Re: Spectra Remote 800mhz to maxtrac 16 pin

Post by akardam »

Well, first off, no, you're not wrong to try and come up with a solution. I just don't think the one you've come up with is going to be practical, or safe.

I'd be real surprised if you could get the necessary isolation by any combination of horizontal or vertical seperation of the trunk radio antenna and maxtrac "extender" antenna on any sort of patrol car.

Let's also assume that your simplex frequencies are in the NPSAC range (866-869 for the moment) as is your trunking system. You mention the 45mhz seperation between TX and RX. That might be OK when your officer is transmitting (portable to maxtrac on 866, trunk radio turns around and tx's down at 821, for 45mhz seperation) but what happens when the trunk radio is recieving? Trunk radio rx's on 866, maxtrac retransmits on 866, insta-desense.

You mention putting this solution up at a local station. Ok, now we have a tower (or at least a building) to work with, so chances of isolation between the antennas are better.

You still need to worry about how the trunk radio and the extender interact. You mention a quick key-and-release to see if you get the talk permit tone. Can you guarantee that the extender keyup will always be quick enough to head the talk permit tone coming back? Can you guarantee that if the radio gets a channel grant during the extender "kerchunk" that it will in a subsiquent keyup?

Let's look at this from another perspective. Who runs the trunking system? You mention a small village, so I'm assuming that the county (or some larger agency) runs the system and your village subscribes to the system. Have you talked to the people that run the system about your coverage issues?

The final, and most important thing as far as I'm concerned, is the aforementioned life/officer safety issue, but you also mention that you'd be doing this out of your own pocket, which could open up a liability issue. Let's assume you do cobble something together and it works well enough most of the time but at a critical moment it fails/doesn't work and someone gets hurt or dies. Questions will be asked and I bet you dollars to doughnuts that the finger will be pointed in your direction.
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