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New Repeater in Northwest Indiana


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#1 n4gix

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Posted 10 February 2016 - 04:05 PM

Well I finally have managed to bring the "Hammond675" repeater online, at least on an experimental basis. The repeater consists of two Motorola CDM1550 LS radios, a simple controller, duplexer, 50' RG213/U coax and a simple UHF antenna mounted around 42' on the peak of my home's roof.

 

I don't expect great coverage with only 10 watts, but that's the best I can afford at the moment. When spring comes around again, I'll have a friend who's still able to climb around install a better antenna and 1/4" Superflex Heliax cable. I'll also replace the jumpers to the duplexer with 1/4" Superflex Heliax at the same time.

 

Now if I can just figure out why the transmitter starts at 12 watts, droops to about 5 watts, then within one second ramps back up to a steady 10 watts! :huh:

 

Having looked around carefully, I've modified my original plan to use 467.725 and have set the system to use 467.675 PL xxx.x since no one within 70 direct miles from me is using that frequency. ;)



#2 Logan5

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Posted 10 February 2016 - 04:52 PM

antenna height and quality feed line IMHO far more important than watt's. depending on topography 42 feet at 10watt's might just surprise you. 



#3 Logan5

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Posted 10 February 2016 - 04:53 PM

Power droop? could be the power supply.



#4 Logan5

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Posted 10 February 2016 - 04:55 PM

for your setup, I would put an in line battery and a charger power supply.



#5 n4gix

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Posted 10 February 2016 - 05:29 PM

Eventually, perhaps. An adequate LiFEPO4 battery is around $130 though. Since this is at home, for the time being I'll plug the repeater into one of my spare UPS units.

 

This has a 13.86vdc  30amp power supply, so I'd be surprised if the PS is responsible for the power droop. Here is a picture of it on my desk while making sure everything is wired correctly! :D

nKO3H1.jpg

 

Here is a picture of its final home. I haven't installed the vented front panel yet.

Attached File  2016-01-15 20.55.59.jpg   419.36KB   1 downloads


Edited by n4gix, 12 February 2016 - 09:31 AM.


#6 n4gix

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Posted 10 February 2016 - 05:57 PM

antenna height and quality feed line IMHO far more important than watt's. depending on topography 42 feet at 10watt's might just surprise you. 

Well, I'm located at the southern tip of Lake Michigan, and there are darn few hills anywhere near me. I expect terrific coverage of southern Lake Michigan!  Anywhere around the steel mills however, not so much... :wacko:

 

Most certainly my weakest link at the moment is the antenna and feed line. Those will be the first items on the Spring Agenda. :lol:



#7 Logan5

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Posted 10 February 2016 - 07:58 PM

they make a 5' tripod, mine is made by EasyUp that can be mounted on straddling your peak with 9 lags. I have used with a 10' segment of 1 1/2" mast that can increase you by another 11 to 14', I have even used another product to overlap and piggy back another segment for 20+ feet. the second product makes it easy to drop it 8 to 9 feet in the event of high winds. both made by EasyUp. comparable to Rohn products by much better prices.



#8 n4gix

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Posted 12 February 2016 - 09:32 AM

Oh my! I may as well be trying to use a dummy load for an antenna. Yesterday a quick test demonstrated that I currently have slightly less than a 1 block radius of coverage... :blink:



#9 Corey

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Posted 12 February 2016 - 11:40 AM

Check your SWR between the transmitter and the duplexer, then check it again between the duplexer and antenna, something is definitely wrong! If the duplexer and antenna check out swap the radios and test again.

 

Corey


Just My $.02

 

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#10 Logan5

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Posted 12 February 2016 - 11:46 AM

I suspect damaged feedline or a connector.



#11 n4gix

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Posted 12 February 2016 - 02:18 PM

Check your SWR between the transmitter and the duplexer, then check it again between the duplexer and antenna, something is definitely wrong! If the duplexer and antenna check out swap the radios and test again.

SWR checks out at 1.1:1 to the antenna. Both radios direct to the antenna show a solid 25 watts. I'll put my meter between the transmitter and duplexer after awhile to check SWR.

 

I suspect that the so-called "free tuning to my frequency" offered by the seller was not done properly (or at all for that matter). I've checked with my fellow hams here in the area and no one knows of anyone with a spectrum analyzer to check and tune it properly. When I sold South Texas Radio (GESS) twenty-five years ago, all my test gear was part of the sale.

 

Another test I can do is to use two antennas and by-pass the duplexer. I have two antennas around 40' apart on the roof of my house.



#12 Corey

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Posted 12 February 2016 - 02:45 PM

My suggestion to test between the radio and duplexer would have told you if the tune was good or not.


Just My $.02

 

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#13 n4gix

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Posted 12 February 2016 - 03:17 PM

Yes it should. I will get to this after awhile when I can set aside some time.



#14 ASRM

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Posted 13 February 2016 - 08:48 AM

At 40 feet and no hills you should get any easy 20 miles, we are 40 feet on a bluff, even with hills and dips between our mobiles we are easy 10 miles, LOS NW on our system is 25+ miles in spots, that is with a 6DB/9DBi Comet. We used 1/2 Heliax with a Vertex repeater tuned down to 30 watts or so. I did have my duplexer checked by a local shop.

 

The 1 mile range is troublesome. Have you at least tried to bypass the duplexer and see if you can hear a unit 5 or more miles out or transmit the same?

 

Nice setup and congrats.



#15 n4gix

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Posted 13 February 2016 - 11:26 AM

I finally (after nineteen years of procrastination) decided to join the Lake County Amateur Radio Club last night. After the meeting I spoke with a member who had presented the evening's program on "Texas Eggbeater" satellite antennas and he indicated his willingness to help me tune up the duplexer properly.

 

In the meantime I'm going to ship both my Ritron RRX450 repeaters down to Carmel, Indiana so the factory can repair and/or tune them up properly. I'll probably then put the "Gator Box Portable Repeater" up for sale once the duplexer is tuned and I've got it completely assembled.



#16 quarterwave

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Posted 13 February 2016 - 01:58 PM

It doesn't take much for one of those duplexers to be off and cost you your power out or rx in. I have a celwave and it needs retuned once a year, the antenna and line are fine, it just take a minor tweaking and she comes back. They are touchy in my experience. I "backwoods" tune my stuff since I don't own a service monitor. Usually close enough for me. I found a quarter turn on one of the cans equaled half my power once. 



#17 NavyBOFH

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Posted 13 February 2016 - 05:43 PM

I gotta ask - where did you find the power supply? I am trying to use the SAME mounting (found on ebay) and put on it the power supply, duplexer, and repeater controller to make one easy unit - then maybe stuff it all into a small case with fans and call it a day. Did the tray you mounted the duplexer and PS to come with it?



#18 n4gix

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Posted 13 February 2016 - 06:05 PM

I ordered the smaller shelf from here: http://www.ebay.com/itm/161798724686 for $15. I went to my local Menards (like Home Depot) and bought four six inch threaded screws, lock washers and nuts. I drilled matching holes for the four long screws and used the lock washers and nuts to secure the tray. Both the duplexer and power supply are mounted with large strips of Velcro.

 

The power supply came from here: http://www.ebay.com/...R-/121880601988? for $34.99 + shipping.

 

Not seen in the photos is a vented 2u front panel that will both hide and protect the duplexer and power supply from curious fingers...

 

I had emailed the gentleman from whom I bought the custom tray and front panel and inquired about a vented panel and tray, but he said it would cost nearly as much as the custom one I'd already bought. I figured I could do it myself a lot cheaper!

 

The reason for choosing a "Gator Box" is that this is intended to be a "portable repeater" for off-the-grid use mostly. For that reason both radios have all eight GMRS frequencies programmed. It's a shame that the PL tone is not changeable without resorting to the CSS, but then for where it's going to be used that probably won't be much of a problem.

 

The "Gator Box" has ample room to accommodate one or two LiFEPRO4 batteries, a charging circuit, and a fifty feet of coax and antenna, with a weighted rope that can be used to pull the antenna and coax up into a handy tree branch.



#19 NavyBOFH

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Posted 13 February 2016 - 08:22 PM

That's a pretty good idea. My idea is to keep it "semi-permanent" but mostly that I want it to look clean in the sense that it looks good in my home, or will be protected in a different site. I saw the Gator Box but wanted something smaller since a 4u setup that shallow doesn't need so much rack space.

 

Thanks for the links though! I saw that power supply but was afraid to use it. Now I know it will work just fine.



#20 n4gix

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Posted 13 February 2016 - 09:06 PM

I've seen several really nice wood 4u cases, both straight and sloped. I'm actually going to make my own using 8u rails and base legs. I can easily cut sides and a top for it and give it a nice finish. This will be for my desktop eventually, so I have less of a clutter here.

 

http://cgi.ebay.com/...id=519033038027

  1. CS800 (DMR)
  2. TYT TH-7800 (dual band 2m/70cm)
  3. HP1 (scanner)
  4. BDD436HP (scanner)
  5. Diamond SX-600 (Watt Meter/SWR)
  6. Kenwood 840
  7. Kenwood 880





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