GRMS and part 90 repeaters

[Jarozzy]

Hello all, I am new and learning.  So if this isn't in the right place please forgive me.  Our farm has a part 90 repeater in the 463mhz and 468mhz frequencies.  Since we already have an anntena on our 135ft grain leg could I add a GMRS repeater, so one anntenna and two repeaters?  

If so then would traffic on the GMRS repeater limit or disrupt our business part 90 signals?

[gortex2]

Not without a lot of money on combiners and filtering. It is done in the commercial world but its definitely not cheap. You would be better off adding a second antenna with hardline for the GMRS repeater. 

[Jarozzy]

gortex2 thank you foe the reply.

[Radioguy7268]

Assuming you don't need to hire a climbing crew to install that new antenna & hardline, then yes, the price of a 2nd antenna & line is probably much less than a tuned transmit combiner & receive multicoupler system.

Having two repeaters close in proximity and close in frequency can lead to some issues if you're just using compact (inexpensive flat pack notch) duplexers that have very little protection from adjacent signals.  Meaning that if you try to use the 462 GMRS repeater at the same time as the 463 Part 90 machine, you could create some of your own interference. If you're not keying both machines at the same time, then you're probably good to go. 

If you want to have both repeaters keyed up at the same time,  you'll either need to use better quality filtering (think high end $1500+ bandpass/band reject cavity duplexer per machine) or a quality transmitter combiner system. Not many 'hobby' type systems can cost justify a combiner.

[Jarozzy]

I was hoping that it would be relatively cheap.  If it was doable and all I had to do is get a repeater then it would be worth doing.  But if it will be expensive, difficult, and cause issue with our business frequencies then it isn't worth doing.

Thanks

[WRXL324]

I have two repeaters on the grain leg with two separate antennas and no issues. the business repeater is at 461/466 and the GMRS repeater is at 462/467. I will emphasize that each repeater is is isolated from one another in their own steel weatherproof boxes bolted to the tower leg (one above the other). they both have their own power supplies and using LMR400 straight up the leg secured to a wire conduit that goes to the top to power the elevator belt. I made sure that my business antenna got higher in the air then my GMRS antenna. I installed all of my own radio equipment myself and pulled all the coax myself also. the only hard part was when i got to the top platform on the leg and pulled up my bag of tools, i realized i forgot the wrenches i set down on the front seat of my pickup. so after three climbs (of witch two of them could have been avoided all together) I had my stuff installed in about 4 hours!  

[gortex2]

A RT97/Midland with 3' of LMR and antenna is ideal for what you want to do if you have 110V at the top of the silo. 

[WRXL324]

11 hours ago, gortex2 said:

A RT97/Midland with 3' of LMR and antenna is ideal for what you want to do if you have 110V at the top of the silo. 

gortex2 that is the ideal location especially for how short the coax run would be. I was going to do that myself but steered away from it because of the amount of work required to get all that equipment up there. Reason number two was because if something should happen with the repeater itself, that's a lot of climbing for something that could be easily checked and/or repaired standing on the ground. We don't have a lot of platform space on top of our tower to begin with and if you needed a crane to get in there for an elevator repair, it was just another item taking up much needed space at that point. But like I said in the beginning, that would be the ideal location for it all- at the top.

[gortex2]

The midland/RT97 is small enough you could mount to rail.. Midland says weight is something like 5# if i recall. Not bad to have to take down. Power is not what a full blown repeater is but 5 watts in a good antenna up in the air works wonders. Worth looking at.