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buying a good used GMRS repeater for neighborhood watch


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#41 Logan5

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Posted 07 April 2013 - 09:23 PM

Yes, JohnE, I am going to switch over to my batterys over the next few days.eleminating the AC power supply. Wide band is working well, a lil static, in addition to the Hum. but useable, I went to the beach earlier, and Keyed up the repeater close to 2 miles. mind you this is with a non optimal twin antenna set up. after I get a duplexer and or get this duplexer tuned. and stablize this set up, I will list it in the "With Permission" repeaters section. I have learned a lot of the past week. I decline to open an E-bay dispute, as this seller seems like an old guy much in my same situation, and I did end up geting this monster working. so I am satisfied. you guys have been awesome and of course YouTube for instruction. If any of you get to Fort Lauderdale, try to key me up my repeater and say Hi.



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Posted 10 April 2013 - 06:49 PM

Logan5,

If you have not bought the repeater for $229.00 checked by a Motorola technician let it go buy.I bought one several years ago and had nothing but head aches from it and also had a friend buy one a few weeks ago and it is not right either,programmed wrong CW ID doesn't work.The only reason the bought it was for amateur radio and it will not work in many different ways...William



#43 Logan5

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Posted 11 April 2013 - 06:09 PM

with careful antenna placement on my roof top mast. I am getting quite the range now. Several miles in most areas. still on 2 separate antennas. the UVS 200 is RX on top and the TX is now a Blonder Tongue Log periodic yagi, for UHF TV but seems to work quite well, I have a pre tuned duplexer I am hopeful will arrive tomorrow, so as to get the yagi off my mast. all and all I am happy with the Uniden repeater, but the seller should have been more careful shipping an item of this nature. I pulled the duplexer out of the unit and it is not tuned to the same freq. as the radio, I assume anyone that tuned duplexers would affix a new label or use a marker to update the freq. listed. and that has not been done. so I will look for a local shop that will do it. anyone know how much that should cost?



#44 Logan5

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Posted 11 April 2013 - 06:22 PM

with careful antenna placement on my roof top mast. I am getting quite the range now. Several miles in most areas. still on 2 separate antennas. the UVS 200 is RX on top an



#45 PastorGary

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Posted 11 April 2013 - 06:26 PM

In general terms, if a commercial radio shop does things correctly with a service monitor, the re-tuning should take 30 to 45 minutes of bench time.  It all depends upon what their hourly rate is and if they charge a full hour for anything UP TO an hour or not.

 

The local repeater tower close by is 197 feet above ground and the hill it's on is another 271 feet above the average terrain. It has a 50 watt output into a 15.6 db gain omni directional array and has coverage diameter of around 110 miles from mobiles. You don't have that much natural height in Florida so whatever you can squeeze out of it is a plus.



#46 Logan5

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Posted 11 April 2013 - 06:52 PM

Yep the tip of my UVs 200 is only about 37 feet, but is mostly unobstructed . when I move into my new house, I plan to get a 35 to 40 foot tower, but since i am always experimenting with antennas and different frequency's I am thinking a telescoping or tilt over tower as well. if i could use one antenna for everything it would save me much aggravation, but I keep hearing you need a dedicated antenna for the repeater.  I currently have 3 runs of LMR400 to the roof. RX and TX for the repeater and another for the antenna for my Handheld. and another question when they tune a duplexer is it so exact as the 462.675/467.675 or just 462.xxx/467.xxx?



#47 JohnE

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Posted 11 April 2013 - 08:35 PM

it should be exact. can you post a pic of the filter in question? also did you solve you "hum" problem?

a crank up tower would be nice but you still have to climb to cange antennas. I'm still in the process of putting somthing together for my machine at my house. looks like its going to be 50' of galv EMT w/guys. don't really want to get involved w/ree climbing.

 

 Gary, what antenna is that w/all the gain?


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#48 Logan5

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Posted 11 April 2013 - 09:58 PM

"Gary, what antenna is that w/all the gain?" lol, I know right, I was thinking the same thing. sounds like a Yagi antenna.

 

Yes, I properly mounted the internal power to the chassis and the hum is almost non existent.  at this point I have rebuilt the interns of the unit, replaced the duplexer cables. my only problem seems when some users key up I can not hear any voice, even though I know they are talking, AlI I hear on my end is a mic being keyed over and over during that transmission,. perplexing.



#49 PastorGary

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Posted 12 April 2013 - 05:14 AM

(1) If "some users" still have their equipment set to "narrowband"  11K0F3E  - you may not adequately hear them on a wideband system.

 

(2) It is not a single vertical omnidirectional antenna... it is a stacked array.  I don't have a photo of the actual system... it's too high up for my camera to properly show detail. The system was installed commercially and it is somewhat similar to the system in this imaging below,  but there are three of these elements on tower top outriggers:

 

cdf450arraypic.jpg



#50 Logan5

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Posted 12 April 2013 - 01:48 PM

com



#51 Logan5

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Posted 12 April 2013 - 01:51 PM

I have seen this type antenna in a junk pile more than 12 years ago. if I had known then. what i know now.



#52 PastorGary

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Posted 12 April 2013 - 05:22 PM

Even a single stack such as that will give you just under 6dbi gain.  With a 50 watt repeater and figuring a small amount of line loss, that's still an ERP of around 109 watts or EIRP of 179 watts.  Check with JohnE concerning a coverage area  - that should be easy to calculate with his software because your part of Florida is nearly flat. 

 

 

Good luck on your project!!  ;)



#53 Billy

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Posted 12 April 2013 - 06:04 PM

Have seen used on ebay. Still pricey.

#54 JohnE

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Posted 12 April 2013 - 06:18 PM

you have LMR 400 witch IMO is a little better that you average 213 cable. losses at 450Mc by the book are 2.5db/100'. in the grand scheme of things you total losses (duplexer/line/insertion) will be  ~2.5dB so any antenna you can get to get over that would be good. I personally use fiberglass sticks w/5dB gain typically, they can be had for $100.

on control's I use 5 or 6 element yagi's.

one of these yrs I'll put a set of yagis in a stacked array like the folded dipole's just to see how it will work for s&giggles. one of my RF engineer friends thinks I'm out of my mind, but hey there nothing wrong w/experimenting.

link to the propagation software http://lrcov.crc.ca/main/


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#55 Logan5

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Posted 13 April 2013 - 04:58 PM

Logan5,

If you have not bought the repeater for $229.00 checked by a Motorola technician let it go buy.I bought one several years ago and had nothing but head aches from it and also had a friend buy one a few weeks ago and it is not right either,programmed wrong CW ID doesn't work.The only reason the bought it was for amateur radio and it will not work in many different ways...William

Thanks William, I did end up buying the Motorola. it arrived this morning, I connected it to a pretuned duplexer I had already ordered and I like it better than the Uniden. mostly because it's small and light weight. the technician/seller claims it's a 30 watt set up, and I forgot to ask if it's a 25 watt radio with a boost. or if it's a 40 watt radio turned down to 30. someone mentioned this radio does not come in 30watt's I will have to ask, but so far I am getting even better range than the uniden. I have FTL600 and FTL675 but only have one up at a time.



#56 JohnE

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Posted 14 April 2013 - 08:53 PM

do us a favor

measure the output before and after the duplexer, I'm curious about how much loss it has. if its a good tune your losses will be ~6W based on the 30W its suppose to do.

this was one of those Chinese filters ,right?


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#57 Logan5

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Posted 14 April 2013 - 10:12 PM

nope, it's an RFS same company as cell wave out of Marbouro new Jersey. The other duplexer I have is an actual Cell wave and I found a place that tunes them for 45 bucks here on the site.



#58 JohnE

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Posted 15 April 2013 - 06:59 AM

good. those should have a loss of 1.5dB sometimes less and around 75dB of isolation. you'll be good to go w/those.


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Posted 15 April 2013 - 12:54 PM

Logan5 good luck with it,I just know what I was told and I have bought from him also and was not satisfied but it was the radio/WT combo,should have known better....William



#60 Logan5

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Posted 15 April 2013 - 01:19 PM

Thanks again William, I will find another person to tune the duplexer then.






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