RF Linking

[taco6513]

I have read the post from 2016. Didn't provide much more that I already know. However I did lean a new term "Shot Gun".

I would like to link my GMRS repeater to the MWC-550 repeater in OKC. Google maps says 69.995 miles.

The OKC repeater is on platform at 1000 ft on KFOR TV's broadcast tower.

I had one of my members in OKC yesterday. I parked out on the hill with my 40 watt mobile and talked to him just fine.

His audio was really clear, said mine had static but understandable.

 

Guess that is my question. The link radio I use. I was thinking of a Motorola 100 watt or better radio with the power set to 

50 watts. Will doing this get me more duty cycle? Does the group have any suggestions on a link radio?

Things to do to the radio to make it hold up better in this application?

The Arcom RC210 will control the RF link and the AllStar node with lots of options.

 

Yes the owner of MWC-550 WQJX337 has given me permission to RF link with his repeater

 

Also another is antenna separation. The repeater antenna is at 200 ft.. The yagi will be at 25 to 30 ft with a 12.25db 

gain pointed toward the OKC repeater. I am guessing the yagi will direct most of the RF energy down range away

from my repeater. This should mitigate most of the interference.

 

Thanks  
WRCW870

[marcspaz]

I can't help you very much on your specific case, but I would like to provide a little feedback on radios and duty cycle.

 

There is a common misconception that you can take a transmitter and run it at a fraction of its rated output power and get a higher or 100% duty cycle. This is false and you may break your radio. It is true that you will be able to get a higher duty cycle out of the PA(s), but if the entire radio isn't designed for repeater use and 100% duty cycle at some power level, it's going to be a bad choice.

 

Whatever you end up doing, verify the duty cycle with the manufacturer.

[WQYT620]

I would try just adding the yagi antenna first and see how it goes before changing the radio. But as the prior post states using a mobile radio as a link radio you have to be careful of the duty cycle and power out. I have used mobiles as link radios to repeaters that are closer than what you are trying to do that I can tune the power to under 5 watts and works well. 

If you still want to try this, I would keep power as low as possible and be adding a good quality fan/s blowing on the heat sinks continuously. Here is one I like https://www.amazon.com/gp/product/B009OWRMZ6/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

You do have to be care full with fans that can produce electric RF noise in to your radios as well. Such as one that may connect via DC to your power supply that your radio is on.

 

Good luck,

Dan

[WRQD464]

Hello!

          How is this going for you Taco? 

I live in Norman and am attempting to communicate with WQJX337 myself. Looking to utilize his repeater for family radios for the Metro area. With its range it covers us all pretty well. 

Retired vet so I have some spare time I am looking to fill with something I enjoy. Maybe eventually repeater/node myself and go from there. For now, looking to learn and help.

Coy

Have a great one WRQD464 out. 

[gortex2]

So Im a bit confused how are you linking. If your going to be a "mobile" on the 550 repeater that means you are TX at your site on the link radio on 467.550. What is your repeater ? I would assume no matter what you do you will decense the repeater at your site major when the 467.550 radio is keyed. I dont know of a filter that will keep that close of a spacing out of the other. 

RF linking in GMRS is about not able to be done in my process. I can't see where you could get the seperation.

 

[haneysa]

I know of some RF linked GMRS repeaters in Eastern Washington. Those guys are using 550 pair for the link and the 725 pair for the repeater (or vice versa), a large amount of filtering for isolation, and horizontally oriented yagis at both ends of the link. I think there is also a considerable mount of vertical separation between the repeater antennas and the link antennas.

[WRPR796]

Hello all,

At the risk of asking a dumb question, why does everyone worry so much about 100% duty cycle, when as I drive randomly around the country in my semi truck, I can literally go days without a meaningful break of the squelch, is there a region or area where GMRS is actually busy with traffic that someone will have a repeater HOT for 55-60 mins an hour??

Does a person actually need a "linking" radio for something like this? Using the appropriate connection, to keep impedance correct, wouldn't you just add the directional antenna to the current setup to link the two distant systems?

 

I am probably way beyond my pay grade.

Edited April 27, 2022 by WRPR796
a new thought

[OffRoaderX]

1 hour ago, WRPR796 said:

is there a region or area where GMRS is actually busy with traffic that someone will have a repeater HOT for 55-60 mins an hour??

Yes.

[WRPR796]

3 hours ago, OffRoaderX said:

Yes.

Of course the one state with an air resource board that doesn't like my truck, Dang it

[WRPR796]

I think I misunderstood this setup, I thought you were adding an additional radio, rather than replacing the existing one!

My bad!!