gmrs Repeater help please!

[birdieboy]

I am seeking some help on a uniden ARU 250K repeater, mods if this is the wrong place or there is a better place please move, thanks. I have the manual for the repeater but am having trouble tuning it. I am lloking for advice on how to tune and set it up.

I am not going to be using the repeater as a full duty repeater so it should be able to transmit at a full 25 watts, the radios I am using for the system are 4 kenwood tk-3101, I have the software and cable to program them as I was using the radios with another repeater system, and have gotton myself a motorola cp200 with the cps software, I just bought the lasted version off the MOL site, and I will be using 2 motorola EM1000's that are not repeater capable but should be able to use simplex with the other radios in talkaround.

I am using the repeater in the great northwoods and am not expecting great range but 25 watts and 2 and a 4 watt portable should give me 3-4 miles from the tk-3101's and 4-5 miles out of the cp200.

I am looking for any advice on tuning a Uniden ARU250K repeater. thanks for reading my post and for advice offered, as I know I am quite new to repeaters.

[prcguy]

Do you have test equipment suitable for aligning a repeater? Either a service monitor or separate signal generator and power meter, deviation meter, etc and a power attenuator to run the transmitter while simultaneously tuning the receiver. Tuning a duplexer properly requires a scalar or vector network analyzer or service monitor/spectrum analyzer with tracking generator. It can be tuned other ways but I don't recommend it.
prcguy

[birdieboy]

as stated above i am new to this so no i do not have any of the equipment stated above. you said it could be tuned other ways, why would you not reccomend those ways and what are those ways? i will admit it that i am cheap and do not like spending money which im wondering why i have a motorola but that is a different point.

The repeater does not have a duplexer and i am using two antennas on a mast above my house, there is 22 feet vertical spacing between the two antenna and i am sure that is probably overkill for the wattage that the repeater outputs.

Thanks,

Tom

[prcguy]

If you had a signal generator and a spectrum analyzer or 50ohm RF millivolt meter you could align a duplexer but without experience you could easily get it wrong. Seeing the response on an analyzer is best.

Your vertical spacing might be ok if the transmitter has a narrow band pass filter but without test equipment you will never know if there is degradation.

What your attempting would be like me (not a car mechanic) ripping apart the automatic transmission in my truck and making adjustments (if there are any, I don't have a clue) without diagrams or proper tools. The outcome may not be pretty.
prcguy

Originally Posted by birdieboy

as stated above i am new to this so no i do not have any of the equipment stated above. you said it could be tuned other ways, why would you not reccomend those ways and what are those ways? i will admit it that i am cheap and do not like spending money which im wondering why i have a motorola but that is a different point.

The repeater does not have a duplexer and i am using two antennas on a mast above my house, there is 22 feet vertical spacing between the two antenna and i am sure that is probably overkill for the wattage that the repeater outputs.

Thanks,

Tom

[aaron315]

22 feet of vertical separation is only giving you 60db (a generous figure) isolation in your operating range. That assumes perfect feed line, isolation at the repeater its self, etc. Real world: You are lucky if you are getting 25db isolation with your setup described.

Even the cheapest 'mobile' 6 cavity duplexers offer 75db minimum isolation at 5Mhz channel separation.

You will need to nearly double that vertical separation to achieve your goal. But then feed line loss becomes an issue. For maximum performance, the receive antenna should be highest. However, assuming that your repeater is at the base of the antenna support structure AND you are using Belden 9913 properly installed and terminated into a perfect antenna you are looking at nearly 1.5db of loss on a 50' run to the receive the receive antenna.

Look around on Ebay. You can likely pick up a good sinclair 'mobile' style duplexer for around a hundred bucks. With a little communication to the seller, likely it will be shipped tuned to your desired pair. It will save you a lot of frustration, and help you realize the maximum possible return on your overall investment.

[witthoft]

Tom:
First of all I would like to say that I admire your anticipated range of 5 miles. That is a very practical figure for the setup you are working with. Second, I understand your not wanting to much money on your radio system. But, I have to agree with other posts that you will be much disappointed with improperly tuned equipment. I don't know about tuning stuff either. I always pay to have that stuff done. It will be the best money you can spend. Search around, maybe you can find someone around who knows about the repeater you desire to use. IIRC, that machine requires crystals to put it on the right frequency, so that will be an added expense also, probably $100 or so. I have had great success in using two mobile radios link together as a repeater. Then I stepped up to a gr1225. Finding something programmable is another option. Welcome to Repeater Builder Dot Com is a site with some good, useful info. Also realize that for the money of two decent antennas, and two decent feedlines, you can obtain a decent duplexer (under $150). Ebay is a great place to hunt. Good luck!