New Repeater in Northwest Indiana

[n4gix]

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!

 

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.

[Logan5]

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. 

[Logan5]

Power droop? could be the power supply.

[Logan5]

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

[n4gix]

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!

http://imageshack.com/a/img921/3180/nKO3H1.jpg

 

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

Edited February 12, 2016 by n4gix

[n4gix]

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...

 

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

[Logan5]

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.

[n4gix]

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...

[coryb27]

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

[Logan5]

I suspect damaged feedline or a connector.

[n4gix]

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.

[coryb27]

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

[n4gix]

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

[ASRM]

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.

[n4gix]

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.

[quarterwave]

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. 

[Guest]

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?

[n4gix]

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/itm/30-Amp-12-Volt-DC-13-8V-Regulated-Power-Supply-for-Ham-Radio-CB-US-SELLER-/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.

[Guest]

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.

[n4gix]

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/ws/eBayISAPI.dll?ViewItemVersion&item=401058404903&view=all&tid=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

[n4gix]

Having grown tired of fumbling around with my attempts to homebrew my own repeater, I've just ordered a shiny new Bridgecom BCR-40U (400-470 MHz) UHF Repeater, complete with a properly tuned duplexer and the programming kit. It should be here within a week or less.

 

I had my handy man out today taking advantage of the warmer weather and low winds to do some maintenance on my roof mounted antennas. One dual-band antenna's top section was lost several years ago (the VHF part), so I had him swap the coax over to another dual band that I'd put up some years ago as a backup.

 

Hopefully all I'll need for the spring is to buy some 1/4" Superflex heliax and a better antenna for the repeater.

 

I also made contact with another ham in the area who's kindly offered to (re)tune my existing duplexer.

[6040]

Hi Bill, congrats on your new repeater! just wondering, having talked to you a few times on the 600, I know you just started into the digital world. will your new repeater also be digital compatible?

[Logan5]

the BCR40 is not digital and digital is not legal on part95

[n4gix]

Hi Bill, congrats on your new repeater! just wondering, having talked to you a few times on the 600, I know you just started into the digital world. will your new repeater also be digital compatible?

No, this one is strictly analog. The only bands I'm licensed for is in the amateur bands where digital would be legal are already well covered by existing repeaters in Gary, Crown Point, Valparaiso, La Porte, and Chicago. The analog mode is oversaturated with 2m and 70cm repeaters, that are going largely unused.

 

This is why I decided to try setting up a GMRS repeater as a place to experiment and have a bit of fun. If it doesn't work out well, I'm sure it could be used for something else.

[n4gix]

Yesterday I ordered a shiny new spectrum analyzer with tracking generator. It sure is a lot nicer than my old "Cushman Service Monitor" from the old GESS I used to own! Now I'll be able to tune things properly again. No more 'Armstrong Method' more miss than hit.

 

Rigol DSA815-TG Tracking Generator Spectrum Analyzer

http://www.ebay.com/itm/361461963474

 

http://cdn3.volusion.com/gxyha.zuzhq/v/vspfiles/photos/DSA815-TG-3.jpg