Batboard

My local fire company has the ability to program minitor pagers. What we would like to do is have the ability, to keep the cost down from a service monitor (which we don't need all the features) to do 2 tone encoding. We have the software on a laptop, but need to handle the radio side. We will be using a 6watt MT1000 portable and need something to reduce the watts so we aren't tripping pagers all over town. Is the connection on a MT1000 a SMA connection and do I want to use an SMA Attenuator to do this? I am not sure the best way to do it so that we don't hurt the radio. This would just be a 3-4 second transmit time. If I do buy an SMA Attenuator, what dB level would I be looking for? I was thinking 30, but I don't know if that is too much. I only want the radio to transmit several feet or at most 25 feet or so, which would put me transmitting around .06 of a watt. Is this enough? My hopes are to buy something that will just transmit in a small radius. If there is a better solution or idea, please leave me know. We can do the attenuator for around $100, but I am just not sure what is available that is portable and easy.

Thank you in advance,
Jason

The MT1000, HT600, and P200 radios do NOT have a coaxial connector for the antenna. They require a special adaptor that connects to the options pins on the top of the radio. Looks like a speaker/mic connector but has a jack for a RF cable.

http://www.repeater-builder.com/motorol ... er-top.jpg

Also, use a 50 ohm dummy load. They cost much less than an attenuator pad.

Is this the same adapter that connects to an external antenna? I don't have one, but I am sure I can get one somewhere if that is what I need. If you have a part number, or know how I can find one, that might help me out. I am not really familiar with these. What kind of cable would I need then to connect to that? I thought I knew what I needed in my mind earlier, but now I am not sure.

Thanks.

Just curious but instead of the SMA attenuator why can't you just connect the MT1000 portable with this adapter and some cable to a dummy load? The radio is happy because it sees a nice 50 ohm resistive load and you should not be tripping pagers more than 25 feet away. And the cost of a dummy load is well under $100 for something that can handle 6 watts.

HRN wrote:Is this the same adapter that connects to an external antenna? Thanks.

Yes it is, just look for the antenna sign on the adaptor.
NTN5368A RF Adapter
NKN6408A RF cable is nothing more than a 1/8 mono plug that mates to the adapter's jack, coax cable and suitable connector for your dummy load.

You would be much better off purchasing a dedicated RF generator and a tone synthesizer. This way you will have a better grasp on the pager sensitivity.

I bought a Cushman 4000 service monitor to attempt to do this and I was able to get the tone generator to work, some of the buttons stuck, but I couldn't make it transmit. I was told by someone that I had to build something else for it to transmit, but I thought it should do it all on one unit. I couldn't find any help online to figure it out. So I was going to try to sell it and come up with something cheaper.

I'm curious if you looked at this site -

http://comtekk.us/fire-pagers.htm

Comtekk has a tone encoder for a decent price that works via your PC sound card to see if your pager does work. This encoder software can do many different tone formats. The page gives you the details on how "non-technicians" can test a pager. This is definitely the low buck route for sure and you are making compromises of course.

Like the other posters said using a RF generator, etc will give you the sensitivity which is important. The pager may work great in the testing area but you can't say for sure when you are out in the field how well it is capable of receiving. Can't you use the monitor you have to test the minitor's senitivity (receiver only with no tones) to see what the receiver is doing to give you some idea of how well thigns are working?

Comtekk is what has gotten me thinking there is a more inexpensive way than a service monitor. I have downloaded the encoder and successfully transmitted tones and activated pagers. I just want a way to get the watts reduced and I am not sure what connectors and dummy load to get. 50 ohm is what I am planning on getting, from a recommendation on an earlier post here, but I am not sure of the connectors. I thought I needed something that screwed into the MT1000 antenna connection, but then it seemed an option to go off the accessory plug for the speaker mic. I am just looking for the simplist and cheapest way for my fire company to do this. We are a volunteer organization and funds are limited for this type of equipment.

Thanks.

What frequency band are you operating in? You might be able to find a simple foxhunting transmitter kit and adapt it to your needs.

I'll probably get flamed for this, but here goes. Just unscrew the antenna, and let 'er rip . We've been doing this with an old MT500 for years, and it's still kicking. In general, you won't have the radio in transmit long enough to hurt it.

I have seen Motorola's instructors recommend the same method for reducing radiated power, except the radio in question was the (then brand new) XTS3000.

I have been just using it with the antenna off so far, but was afraid, from what I have read, I would burn the radio up. It is only transmitting for approximate 4 seconds at a time. The only problem is, I am not exactly sure, at this point, how far the signal will go without the antenna.

mastr wrote:I have seen Motorola's instructors recommend the same method for reducing radiated power, except the radio in question was the (then brand new) XTS3000.

You could also just connect a 5 or 10 watt 50-ohm
carbon resistor to the antenna output and let 'er rip.
World's cheapest dummy load.

Tom in D.C. wrote:You could also just connect a 5 or 10 watt 50-ohm
carbon resistor to the antenna output and let 'er rip.
World's cheapest dummy load.

I have to suppose that such an animal is readily available in your area. Try finding something like that here!

As for how far it will transmit with no antenna? Not very. I'd say you'd be really lucky to get a signal strong enough to even break the squelch on a receiver much farther than, say, 150 yards or so. If done inside a metal building, you probably won't hear even a whisper of it right outside. As I said earlier, we've been doing it for years, and a guy about three blocks from the building we do it in never hears a thing.