BTech GMRS RPT50 - NEW 50-Watt GMRS Only Repeater

[WRTC928]

18 hours ago, WSHE710 said:

I just ordered one of these repeaters and I'm hoping it will cover my target area. My town is about 4 miles across N S and 4 miles E W. The repeater antenna is on my house which is located almost exactly in the center of the town. The total height of my present antenna (A Comet dual band 17 foot) appears to be about 35 feet to the tip of the antenna. I Will soon be replacing this antenna with a tuned and dedicated GMRS one that the tip will be about 5 feet shorter than the present dual band. This is a relatively flat suburban area with mostly single-family homes. Those who have this repeater already do you foresee any problems with me covering this area reliably with HT 5-Watt handhelds?  And in your experience how much less range do you get using them inside of an auto?

I have one of these with a 712efc antenna on a 30' mast and get about 15 miles coverage with a mobile radio in most directions. Obviously, getting your antenna as high as possible is the best thing you can do to improve coverage, but 2 miles in each direction should be a piece of cake unless you have a lot of tall buildings. TBH, if you have a good SWR on 467 MHz with the current antenna, it might not be worth the cost and effort to replace it with a GMRS-tuned antenna. You're not trying to cover a whole county, so the difference in performance might be negligible or even non-existent.

A 5 watt HT can work my repeater from about 10 miles before the terrain starts to impact it, probably because of the inferior antenna on an HT versus a mobile. Oddly, being inside a vehicle doesn't seem to affect range much, but it does impact clarity. I don't see any difficulty getting the results you want with this repeater. It should handle a 2 mile radius all day every day.

[WRTC928]

13 hours ago, wbjohnston said:

Regarding the height is might rule one can shoot themselves in the foot by running even low loss LMR 400 Coax way up high into a tree and the trade-off would be line loss that would be eaten up in that long run, and the height wouldn’t make up for it at some point.

This is true, but IMO, it's also easy to make a bit too much of it. Some people seem to get obsessed with coax loss without actually running the numbers and finding the "sweet spot" between an ideal situation and a good return on investment. A coax loss calculator can help you figure out what will work best for you. In a practical sense, my experience is that it's almost always worth getting the antenna higher, even in the face of more coax loss, all other things being equal. Most people will tell you that for a run longer than 100', you should consider something less lossy than LMR400, and that's probably good advice, but for most "home users", 100' of coax is going to get you about as high as you can practically go anyway. 

To use a real-world example, my BTech repeater is currently feeding a Comet 712edc antenna with 6.85 dBd (9.0 dBi) gain on a 35' mast. To get from the antenna to the coax panel on my wall requires 50' of LMR400 coax. Plugging that into the coax loss calculator tells me that with 50 watts from the repeater, I'm getting a 28% signal loss for 35.8 watts to the antenna. Using an antenna with 6.85 dBd gain yields an effective radiated power of (ERP) of 174 watts. 

I'm planning to move the antenna to a 50' mast a few away from the current mast which will then require 75' of coax to reach the panel. With 50 watts output, I'll have a 39% signal loss for 30.4 watts to the antenna, or 5.4 watts less than with the 50' of coax. Using the same antenna with 6.85 dBd gain gives me an ERP of 147.5 watts, or a loss of 26.5 watts. Which will increase my range more, 15 more feet of elevation or 26.5 watts more power? 

Power usually doesn't make as much difference as most people think it will, particularly when you're already in the range of ~150 watts. In my case, getting the antenna up another 15' will get it above the hill to the west, which will dramatically increase my range, regardless of wattage. If it were practical to get the antenna another 25' higher, using 100' of coax would decrease my ERP to 125 watts, but in real-world application, that's still a lot of RF power. Heck, in my case, 200' of LMR400 would reduce my ERP to 65 watts, but with 65 watts on a 150' tower, I could probably talk to most of the state. Obviously, there's a point of diminishing returns, and for more than 100', I'd probably go to something less lossy, but then you're talking about more expensive coax.

Don't get too wrapped in the issue of coax loss. Don't ignore it, but don't obsess over it, either.

[SteveShannon]

11 minutes ago, WRTC928 said:

Which will increase my range more, 15 more feet of elevation or 26.5 watts more power? 

Power usually doesn't make as much difference as most people think it will, particularly when you're already in the range of ~150 watts. In my case, getting the antenna up another 15' will get it above the hill to the west, which will dramatically increase my range, regardless of wattage.

This can’t be emphasized enough!!! Great point!

[WSHE710]

Thank you all for the information and advice. I believe my best course of action is to try this repeater on my present antenna and see if it covers the area I want to cover. If it works with my ham antenna there's no reason to change it because the GMRS antennas are shorter and height seems to be the gold standard for two way radios especially repeater work.

WRTC928, if you don't mind me asking what is the total height of your antenna from ground to tip top? I have done some recalculations and I believe my ham antenna from ground to top is about 45 feet and I would lose about 7 to 10 feet by replacing with a GMRS antenna.

[wbjohnston]

46 minutes ago, WSHE710 said:

see if it covers the area I want to cover

That’s the bottom line. We are sharing a resource and just because you can dominate a huge footprint in coverage seems selfish and plain egocentric. Given you likely have some latitude to improve your coverage to obtain a realistic goal the by all means go for it if pocketbook is accommodating. Unfortunately, there is no “frequency coordination“ for GMRS as there is for amateur radio bands. Fortunately, the FCC does not put restrictions on antenna height, the power that actually reaches the antenna after gains/losses, or the size of your footprint coverage. The FCC rules state that you have to work it out amongst yourselves if you’re causing interference (frequency coordination).  I was running into the problem that any increase in coverage came with increase potential of interfering with other systems and therefore decided my current goal of coverage was adequate.  Some guys gobble up as much coverage that is physically and financially possible but then cut anyone else out for using that pair of repeater channels. There is no way of controlling that given current FCC rules and many of us hope that there never is. Get respected frequency coordination groups going like Hams have to help sort things out fairly without stricter rules/laws. 710 you have the right attitude “…see if it covers the area I want to cover”. This hobby/tool will likely survive if we share this resource; imposed restrictions are not the solution. 

[WSHE710]

WB, thanks for the good words of encouragement.  I am a Ham but new to GMRS and I am still learning. You mentioned antenna height. I thought the FCC restricted GMRS antennas to 60 feet I could be wrong cause I'm so new to this but is there something different when using a repeater or did I read the rule wrong?

[LeoG]

Since I know of 2 GMRS repeaters, one on a 200' tower on a 800' mountain and another on a 125' tower on a 700' mountain I'm gonna guess that a bad interpretation.

[WSHE710]

Sorry I did read the rule wrong It's 60 meters not feet. BTW Can you tell me where I have to go to change my avatar like you did?

 

[LeoG]

In your account console.

[WSHE710]

LeoG, i cannot find anything in my account labled account console.  I there another name for it?

[LeoG]

Click on your current avatar and it brings you to your account.  Left side of the screen (computer) shows your avatar.  Click on that and you can upload your picture.

[wbjohnston]

I believe any antenna height regarding GMRS was rescinded after the 2017 revisions. Apparently there is a restriction that the FCC requires one to register height above 200’ from surrounding structures/terrain (not actually sure about that but the word registration is the key thing here) and of course there’s restrictions near an airport. Not withstanding HOAs can have very strict rules, but they’re being challenged.  I think any of the break in the rules the FCC can take action usually in the firm of a letter that asked for compliance but historically, even after complaints, they rarely take any action, and usually start with a letter asking for your compliance. Unless it’s a significant interference or hazard, certainly if one is causing issues with emergency comms or aviation.

[WSHE710]

LeoG, so far so good but what are the black marks on ether side and do you know how I can get rid of them?

[WRTC928]

2 hours ago, WSHE710 said:

WRTC928, if you don't mind me asking what is the total height of your antenna from ground to tip top? I have done some recalculations and I believe my ham antenna from ground to top is about 45 feet and I would lose about 7 to 10 feet by replacing with a GMRS antenna.

The mast is about 35' and the antenna adds about another 10' for about 45' total. In theory, you'll typically get better performance from an antenna tuned for the specific band you want to use, but that varies according to a lot of factors. The truth is, for the coverage you're describing, probably the only difference you'd notice is a hole in your wallet. You do you, but in your circumstances, I'd try what I had and only replace if I weren't satisfied with the results.

[LeoG]

59 minutes ago, WSHE710 said:

LeoG, so far so good but what are the black marks on ether side and do you know how I can get rid of them?

Make the white portion of your picture bigger I'm guessing.

[LeoG]

53 minutes ago, WRTC928 said:

The mast is about 35' and the antenna adds about another 10' for about 45' total. In theory, you'll typically get better performance from an antenna tuned for the specific band you want to use, but that varies according to a lot of factors. The truth is, for the coverage you're describing, probably the only difference you'd notice is a hole in your wallet. You do you, but in your circumstances, I'd try what I had and only replace if I weren't satisfied with the results.

Plus from what I understand the radiating portion of the antenna will be from the center.  So the main radiation pattern will be coming at 40'

[WSHE710]

I have some limited access to a program called chat GPT. It is an AI program that is really amazing and can solve so many different problems quickly. It told me that if I uploaded it a picture of my house with the antenna and gave him a reference of measurement. It could estimate the height. I had a measurement from another project which is 14 feet from the cement driveway to the lower sill of the second story window. (see attached picture). it then calculated that my antenna height was somewhere between 45 and 46 feet from the ground to the very tip. If I do have to replace the antenna with the GMRS antenna I will lose some height. But I have been working on an idea to keep the height a little more in line with what I have now.

I did notice something else though some of the guys on the squad were complaining that they didn’t always hear people, even when they knew they were within range. I was unable to find the original post. But somebody on here commented that they had a problem with one HT that could not reach the repeater. Upon examination they discovered that the repeater squelch was set to six is what I believe he said. He moved the squelch to one, and now that HT can hit the repeater.  This got me to Thinking that maybe some of our HT’s that we’ve got out there are also set too high. And in my testing the Retevis repeater that’s why once I got far enough away from the repeater, I couldn’t hear the audio anymore out of another HT I had 10 feet away.   So, I looked at the two that I had here and sure enough they were set at 5. I moved them down to one and I’m going to Experiment with those HT’s tomorrow. Then when the repeater gets here on Wednesday, I will check the setting on it and see what the setting is, And, if needed bring it down to one or two before I test it.

Unless the repeater gets here sooner than Wednesday I’ll report back Thursday or Friday and let you all know how it all worked out.

[WSHE710]

My BTECh repeater came in this afternoon. Programming was pretty straightforward. After programming I hooked it To my antenna and my Watt meter and got a whopping 31 1/2 watts out of it. I gave it a test run anyway and I could only get about a mile and a half with an HT.  But only if I stuck the radio out the window. I sent an Email BTECH seeing if they could help me with this problem. I'll let you know what they say and if whatever solution they come up with works or doesn't work. I do remember seeing in one of the reviews I think it was from the Queen that there's a knob or a screw on the power supply that you can kick up to get a little more power to the thing but I'll wait until they tell me to do that before I start putting my hands inside there and void the warranty.

[LeoG]

Seems a bit on the low side.  What does the volt meter in the upper right corner of the display say?  The screw you turn is on the power supply.  You can bring it up to 13.8v as long as it's not there already.  Mine was one of the originals, like Randy's 1st one.  They sent me a new duplexer which increased the sensitivity of the receiver by quite a bit.  After that I could put it at 13.8 volts.  Mine runs a bit on the hot side, I keep the voltage lower to keep my output at 50 watts.

Have you checked the squelch level on the repeater?  Original settings put it at 5, the newer setup starts at 1.  If it's not at 1, put it there.

[SteveShannon]

7 minutes ago, WSHE710 said:

My BTECh repeater came in this afternoon. Programming was pretty straightforward. After programming I hooked it To my antenna and my Watt meter and got a whopping 31 1/2 watts out of it. I gave it a test run anyway and I could only get about a mile and a half with an HT.  But only if I stuck the radio out the window. I sent an Email BTECH seeing if they could help me with this problem. I'll let you know what they say and if whatever solution they come up with works or doesn't work. I do remember seeing in one of the reviews I think it was from the Queen that there's a knob or a screw on the power supply that you can kick up to get a little more power to the thing but I'll wait until they tell me to do that before I start putting my hands inside there and void the warranty.

If it’s putting out 31 watts and you’re only getting a mile and a half the problem has nothing to do with output power. I would look at your antenna, your coax, and the location of the antenna. 

[LeoG]

Might as well ask.  What antenna, gain.  What coax and how long.  How high up is the antenna and what's the terrain around you like?  Hills, trees, buildings? 

 

In one direction, towards my house an HTs limit to my repeater is about 2 miles.  But go another 2 miles out and I'm up on a hill and the reception is good.  In another direction where the trees aren't close in and in the way I'm getting close to 6 miles with good quality.  My repeater antenna is 13 meters up.

[WSHE710]

I receive a Reply from BTECH this morning. They also believe the antenna and the cable are the problem not the wattage. The antenna I have up now is a comet GP9 and hase a gain on UHF or 7.6. Here is a link from Amazon where I got it.  https://www.amazon.com/GP-9N-Comet-Dual-Band-Vertical-Antennas/dp/B0DJ1NMS22/ref=sr_1_26?crid=2R8VLCBZWAKKX&dib=eyJ2IjoiMSJ9.VOnahz-sNdbnzvhd5gIcCtvyuFlHzuLjfCsnqzgoC21MoLRGQ-KbkCjowdOqkl-hcCcNjQ44bI15AF2YtfdG1ejDPucXUbL58QkmPHNEIrX_NR5dYzfhR96qrwXTT55v3waz7y_F7LyQ7x_LcsF3n2amYiB933Bu0djd89HSNIJLY3wmnbQ3kfi2ZatOtOsbX_WVnIeXrhmO5_-FBLqs_av0YrGcAJSWaxMXlKO1LQLPDPV65MFrV9oJF0FDrDMJprpoiLwsT18eJSz8ES2ooafhw1KEyLmaKIHwywmSEHo.vrET_jh9bH8u1_Yn2op2izXsr6WVzMbZKwMK1vS3kLI&dib_tag=se&keywords=comet+duel+band+antenna&qid=1761838638&s=electronics&sprefix=comet+duel+band+antenna%2Celectronics%2C159&sr=1-26&xpid=UDO5SwRP2u6EG 

It is a dual band antenna which means it does equally well on UHF as it does on VHF. By the same token it does equally poor on UHF as it does on VHF. So, for the convenience you suffer a little performance. Normally I do not talk long range simplex with  my ham station, I only talk to repeaters and I can reach them with a mag-mount on top of my filing cabinet. So doing away with this antenna doesn’t grieve me at all. I might even be able to sell it to somebody.

The antenna I want to replace it with is a GMRS antenna I also got on Amazon. Here is the link to that antenna https://www.amazon.com/dp/B0CRTRQYKY?ref=fed_asin_title&th=1

My present antenna is approximately 45 feet from the ground to the very tip using RG8 cable that is about 25 to 30 feet long. BTECH suggest that I change the antenna and the cable to the GMRS antenna that I have and also, that I use some LMR 400 cable in place of the RG8. 

The mast that is on there now is about 5 feet and then the Antenna is 17 feet. I have two sections of 10-foot-long old antenna steel mast that the outside diameter is 1 ¼ inch. I am planning on cutting it down to 15 feet because I think 20 is just too long for my tripod. The tripod mounted on my roof is a Skywalker - 5' Heavy Duty Antenna Tripod. The tripod Will swallow about 3 feet of the mast that I’ll be using. This will leave me roughly 12 feet of mass left to attach the GMRS Antenna too. That should give me a total height to the top of the antenna of somewhere around 44 feet, give or take. I can live with this height and antenna; the big problem is finding someone around here willing to go up on my roof and swap them out.  I am 75 and don’t do ladders anymore. One other problem I have is that about 30 yards away from where the antenna is are a couple very old reasonably tall trees. They probably have some influence on my coverage area in the north and northwest sections.

If I can get this antenna situation straightened out, I’ll come back here and let you know how it worked out. Thanks for all the help guys 73’s

 

[LeoG]

Ya.  RG8 is horrible for UHF.  The GP9 seems to be a ham antenna, close but no cigar for GMRS.  If you are going to go for that antenna on Amazon may I suggest going with a Comet CA712EFC instead.  Little more gain and all around good antenna.  And only 2 sections, not three for a total of about 10' tall.  Probably $20 more, but not from Amazon which lists it for $190.

[WRYZ926]

I recommend getting a Comet CA-712EFC as it will be a better antenna compared to the HYS antenna.

https://www.gigaparts.com/comet-ca-712efc-460-470mhz-base-repeater-antenna.html

And yes definitely go with a good quality LMR400 or equivalent coax which will work much better on UHF compared to RG8.

[WRTC928]

I'm going to pile on and say if you're going to buy a GMRS-specific antenna, go with the Comet CA-712EFC. Putting up a new antenna is a bit of a PITA and you don't want to have to find out your antenna is unsatisfactory and do it again. It's worth a few extra bucks to avoid that hassle, to say nothing of the added expense of another antenna. Some dual-band antennas work fine on GMRS, but for a repeater, there's no reason to have additional bands.