Btech Rpt50 Repeater

[Guest John,]

I have this Repeater, it has perfect SWR, pushing Full 50 watts. But I can not receive anyone over a mile away. What is the best way to configure the repeater so that I can receive? 

[OffRoaderX]

There is nothing really to "configure"..

Assuming you have a well placed and well-tuned antenna with no obstructions between you and the other radio a mile away, my guess is that the duplexer is not well-tuned for whatever channel you are using. I would try testing on all 8 repeater channels to see if one works better.

If you still can't get any better than one-mile, and assuming it is not an antenna or terrain issue (ie; if your handheld or mobile radio can reach 5 miles from that same location) then I would contact BTech support and tell them to send you one that works.

 

[SteveShannon]

37 minutes ago, Guest John, said:

I have this Repeater, it has perfect SWR, pushing Full 50 watts. But I can not receive anyone over a mile away. What is the best way to configure the repeater so that I can receive? 

I agree with @OffRoaderX, This sounds like an issue with your antenna, feed line or duplexer. (I suspect feed line).
Try taking the duplexer out of the feedline temporarily (disable transmit first) to see if your receiving range is more reasonable. If it isn’t, look at the feed line and antenna for problems. 
It might be as simple as a very lossy coax cable or even a damaged one. A lossy feed line will also make SWR look really good. 

[Guest John,]

I am using a Btech RPT 50 Repeater, sorry I did not mention that in my first post. 

[SteveShannon]

12 hours ago, Guest John, said:

I am using a Btech RPT 50 Repeater, sorry I did not mention that in my first post. 

What type of coax? What length? What antenna? What duplexer?

[WRYZ926]

24 minutes ago, SteveShannon said:

What type of coax? What length? What antenna? What duplexer?

Knowing that information would definitely help.

Using the best antennas and best coax cable that you can afford is very important  and makes a big difference in performance.

[Guest WRXT295]

Lmr 400 coax,comet gp9

[WSBT338]

Same repeater here, but haven’t tested it yet. Gonna drive away with my 50W Midland MXT500 but waiting for the MXTA26 6dB Gain Whip Antenna to arrive first. See photo for what will be plugged into the RPT50. It’s from DPD Productions and I’m using RG8X. It’s about 30’ up from 14’ elevation. I found a place on the map that gets to 40’ so I’ll probably head in that direction while my wife hangs out at the house. Will report back if you want, but it’ll be next week. Heading out of town tomorrow. Good luck to you! 

[WRYZ926]

@WSBT338 I would definitely go with a different type of coax cable. RG8X has a lot of loss when used for GMRS frequencies. You are looking at a loss of 8.4 dB for a 100 foot run of RG8X, that equates to an 86% power loss. 

Let's say you are using 100 foot of RG8X, you would only be putting out 7 watts at the antenna with a 50 watt radio. Now let's say you are using  50 foot of RG8X with a 50 watt radio. You will have a loss of 4.2 dB which is a 62% loss with only getting an output power of 18.9 watts. 

[WSBT338]

8 minutes ago, WRYZ926 said:

@WSBT338 I would definitely go with a different type of coax cable. RG8X has a lot of loss when used for GMRS frequencies. You are looking at a loss of 8.4 dB for a 100 foot run of RG8X, that equates to an 86% power loss. 

Let's say you are using 100 foot of RG8X, you would only be putting out 7 watts at the antenna with a 50 watt radio. Now let's say you are using  50 foot of RG8X with a 50 watt radio. You will have a loss of 4.2 dB which is a 62% loss with only getting an output power of 18.9 watts. 

Dave Duncan at DPD Productions makes a living on antenna's and disagrees with your assessment. He doesn't even sell LMR400.

[WRYZ926]

43 minutes ago, WSBT338 said:

Dave Duncan at DPD Productions makes a living on antenna's and disagrees with your assessment. He doesn't even sell LMR400.

I'm not going to argue with you. It is a well known fact that RG8 and RG8X has high loss on UHF frequencies. Here is one of the better loss calculators I have found.

https://kv5r.com/ham-radio/coax-loss-calculator/

I suggest doing your own investigation. You will find that RG8 and RG8X are not good for UHF frequencies.

[Socalgmrs]

I’d totally agree to dump the rg8 for lmr400.  But I’d also get a better antenna for the base as well.  Kinda neutered your 50watt radio with all that cable and antenna.  

[WSBT338]

23 minutes ago, WRXP381 said:

I’d totally agree to dump the rg8 for lmr400.  But I’d also get a better antenna for the base as well.  Kinda neutered your 50watt radio with all that cable and antenna.  

Sorry to hijack this thread  If I were to look at another antenna to go with 50' of LMR400 what would you suggest?

[WRWE456]

2 hours ago, WSBT338 said:

Dave Duncan at DPD Productions makes a living on antenna's and disagrees with your assessment. He doesn't even sell LMR400.

This is right from the specs on DPD's ad for 50 ft of RG8x.

Performance: This cable is fine for short runs from your device to an antenna, but not recommended for critical loss applications above 400 MHz at this length. Using this cable at this length on something like ADS-B, is probably going to create some loss.

All he sells is RG8x.

[WSBT338]

1 hour ago, WRWE456 said:

This is right from the specs on DPD's ad for 50 ft of RG8x.

Performance: This cable is fine for short runs from your device to an antenna, but not recommended for critical loss applications above 400 MHz at this length. Using this cable at this length on something like ADS-B, is probably going to create some loss.

All he sells is RG8x.

Never saw that  I'll see how my existing setup works, and if it doesn't perform, I'll look into changing it up. Thanks. And hope the OP can figure his situation out too. I'd be experimenting with other channels right away per suggestion above.

[warthog74]

On 7/2/2024 at 5:54 PM, WSBT338 said:

I’m using RG8X. It’s about 30’ up from 14’ elevation

Agree with the others. RG8/X is fine for 10/11 meter, but your repeater will suffer massive line loss on GMRS. Also only 30 feet high with RG8/X coax will result in horrible repeater performance. You'll be lucky to cover 2 miles. I use LMR400 on a 50 foot run. I had my neighborhood repeater antenna at 30 feet for a while, but coverage wasn't that great. I recently popped it up another 20 feet to 50 feet and i more than doubled my range that's now averaging 10 miles on a 2 watt repeater. Notice that i now am higher than most the trees around vs at 30 feet i was being blocked by trees. The higher you can get that antenna the better your results will be.

You also asked about antenna recommendations. I personally use a copper j-pole tuned to gmrs frequencies. Durable, light, cheap, effective. There are better and more expensive antennas, but for home / non commercial use, these work very well.

[Borage257]

Ed fong gmrs collinear, any of the tram/comet etc collinear ground plane antenna. 

[WRYZ926]

On 7/1/2024 at 4:15 PM, Guest WRXT295 said:

Lmr 400 coax,comet gp9

I have to agree with others that you might want to contact B-Tech about the issue. Sounds like there might be a problem with the duplexer. You are using good coax and a good antenna.

How high is the antenna above ground and is there any obstructions such as trees or building near by?

[WSBT338]

On 7/3/2024 at 7:42 PM, warthog74 said:

Agree with the others. RG8/X is fine for 10/11 meter, but your repeater will suffer massive line loss on GMRS. Also only 30 feet high with RG8/X coax will result in horrible repeater performance. You'll be lucky to cover 2 miles.

I appreciate the expert opinions, and I did order LMR400 to replace my RG-8X. That being said, with my existing coax I clearly spoke with someone on a repeater 40 miles away.

[AdmiralCochrane]

1 hour ago, WSBT338 said:

I appreciate the expert opinions, and I did order LMR400 to replace my RG-8X. That being said, with my existing coax I clearly spoke with someone on a repeater 40 miles away.

Line of sight is more important than power delivered to the antenna; it's possible to hit 40 miles line of sight with less than 5 watts.

[SteveShannon]

2 hours ago, AdmiralCochrane said:

Line of sight is more important than power delivered to the antenna; it's possible to hit 40 miles line of sight with less than 5 watts.

This cannot be stressed enough.  People routinely talk to the space station using 5 watt radios and it’s more than 200 miles away, but there’s nothing in the way.

[warthog74]

5 hours ago, WSBT338 said:

That being said, with my existing coax I clearly spoke with someone on a repeater 40 miles away.

There is a big difference between just transmitting to another station vs running your own repeater. Transmitting to a station 40 miles away doesn't necessarily mean your repeater will cover the same 40 miles using the same antenna and coax. There are a lot more variables involved. Great to see you ordered some better coax though. Let us know how it works out once in operation.

[WRXB215]

3 hours ago, SteveShannon said:

5 hours ago, AdmiralCochrane said:

Line of sight is more important than power delivered to the antenna; it's possible to hit 40 miles line of sight with less than 5 watts.

This cannot be stressed enough.  People routinely talk to the space station using 5 watt radios and it’s more than 200 miles away, but there’s nothing in the way.

I agree. It would be nice if I could get that kind of line-of-sight. But I can't. Some of us just can't get an antenna up above the 100'+ trees around us. 

[WSBT338]

On 7/5/2024 at 3:30 PM, WRXB215 said:

I agree. It would be nice if I could get that kind of line-of-sight. But I can't. Some of us just can't get an antenna up above the 100'+ trees around us. 

Agreed. As mentioned, I’m at about 44’ above street level which is as high as I’ll be able to go. We’ll see if I can get through the treetops. BTW, LMR400 is bad ass. I had no idea. Replaced my 50’ run yesterday. Will be testing longer distance than the driveway to my wife in the house very soon 

[SteveShannon]

47 minutes ago, WSBT338 said:

Agreed. As mentioned, I’m at about 44’ above street level which is as high as I’ll be able to go. We’ll see if I can get through the treetops. BTW, LMR400 is bad ass. I had no idea. Replaced my 50’ run yesterday. Will be testing longer distance than the driveway to my wife in the house very soon 

People sometimes get hung up on height.  We have 60 miles and several mountain passes between Butte and Helena Montana. It’s extremely difficult to get higher than the mountains to get line of sight. Yet we have a guy who checks into our 2 meter Net from Helena. We asked how. He does it by bouncing his signal off a mountain that’s in his sight line.  I don’t know if something like that could be done in your instance, but look for high topographical features and see what happens.