Connected to a Repeater over 75 miles Away! How?

[3cRadio]

greetings all!

new to gmrs radio and had a repeater question.  anyone now how its possible for my base station (20w) radio to make contact (receive & transmit) to a repeater that's over 75 miles away?  i'm using a amazon special gmrs fiberglass antenna that's only mounted 10 ft off the ground.  i have a local repeater approx. 6 miles away that uses .575 frequency with a tone of 162.2 in and out.  i can't connect with it due to a mountain in between it and my location.  as stated, the other evening i was able to communicate with the repeater that's further away which does have a .575 frequency with a tone of 162.2 in but 198.8 out.  i'm not sure how this is possible; am i some how connecting to the repeater local to me and it relaying he signal to the further repeater even though it has a different output tone?

[SteveShannon]

6 minutes ago, 3cRadio said:

greetings all!

new to gmrs radio and had a repeater question.  anyone now how its possible for my base station (20w) radio to make contact (receive & transmit) to a repeater that's over 75 miles away?  i'm using a amazon special gmrs fiberglass antenna that's only mounted 10 ft off the ground.  i have a local repeater approx. 6 miles away that uses .575 frequency with a tone of 162.2 in and out.  i can't connect with it due to a mountain in between it and my location.  as stated, the other evening i was able to communicate with the repeater that's further away which does have a .575 frequency with a tone of 162.2 in but 198.8 out.  i'm not sure how this is possible; am i some how connecting to the repeater local to me and it relaying he signal to the further repeater even though it has a different output tone?

It’s possible that it is tropospheric ducting. It’s also possible that the farther repeater’s signal is getting to you because they have a very high antenna or because it is reflecting off something or refracting over a sharp edge. 
And it’s also possible that the distant repeater is linked with a nearby repeater. 
If your radio doesn’t have a receive tone set, it won’t matter what the repeater output tone is; your radio will allow the audio to be reproduced. 

[OffRoaderX]

Is there a mountain between you and the further away repeater like with the closer one?

I regularly and normally connect to a repeater 69 miles away on my handheld radios and using my base-station with a big antenna on the roof, i can connect to repeaters 80 or 90 miles away - yet there are other repeaters 10 miles away that I cant connect to because of hills/mountains.

[dosw]

29 minutes ago, 3cRadio said:

greetings all!

new to gmrs radio and had a repeater question.  anyone now how its possible for my base station (20w) radio to make contact (receive & transmit) to a repeater that's over 75 miles away?  i'm using a amazon special gmrs fiberglass antenna that's only mounted 10 ft off the ground.  i have a local repeater approx. 6 miles away that uses .575 frequency with a tone of 162.2 in and out.  i can't connect with it due to a mountain in between it and my location.  as stated, the other evening i was able to communicate with the repeater that's further away which does have a .575 frequency with a tone of 162.2 in but 198.8 out.  i'm not sure how this is possible; am i some how connecting to the repeater local to me and it relaying he signal to the further repeater even though it has a different output tone?

You think that's amazing, consider that with a handheld Yagi antenna an amateur can talk through the International Space Station's 2m/70cm (VHF/UHF) crossband repeater using a 5w handheld radio. Five watts, to reach a repeater hundreds, even a thousand miles away.

But what's different about the ISS? It's not that the repeater is a ham repeater. It's not that the repeater has some amazing antenna. It's not that it's got a million dollar radio. It's that there's nothing between you on the ground, and the repeater up in space. Line of sight.

So if you're able to reach a repeater 75 miles away reliably from an antenna that is 10 feet above the ground, that repeater's antenna must be at about 1050 feet above the ground between the two of you. Otherwise the curvature of the earth gets in the way. As an example, I can easily hit this repeater:

But I can hit it because I live at 1600m, the repeater is at 1700m, and everything between us is at 1200m. We have line of sight.

[3cRadio]

5 hours ago, SteveShannon said:

It’s possible that it is tropospheric ducting. It’s also possible that the farther repeater’s signal is getting to you because they have a very high antenna or because it is reflecting off something or refracting over a sharp edge. 
And it’s also possible that the distant repeater is linked with a nearby repeater. 
If your radio doesn’t have a receive tone set, it won’t matter what the repeater output tone is; your radio will allow the audio to be reproduced. 

thanks for the reply!  never hear of tropospheric ducting but after looking it up, it's very possible.  supposedly in area Aug & Sept have a higher probably of this happening.

i'm not familiar with the linking of repeaters but from my understanding this is considered illegal with gmrs repeater but the repeater is operated by a radio network that has a few repeater near each other; maybe they are linked somehow.

my radio tones are set to 162.2 in and out, so no sure how i could hear them on the receive side; that still puzzles me.

thanks again for the reply!

[WRXB215]

@OffRoaderX I'm no expert but your situation sounds like it may be what's called "knife edge diffraction."

[3cRadio]

5 hours ago, OffRoaderX said:

Is there a mountain between you and the further away repeater like with the closer one?

I regularly and normally connect to a repeater 69 miles away on my handheld radios and using my base-station with a big antenna on the roof, i can connect to repeaters 80 or 90 miles away - yet there are other repeaters 10 miles away that I cant connect to because of hills/mountains.

thanks for the reply! there isn't a mountain as high as the closer repeater but i'm located in norcal (suburbs) and there are hills, trees and several buildings towards the further repeater; no real line of sight, open fields or deserts.

if i'm correct in thinking who you are; love your vids!

[OffRoaderX]

59 minutes ago, WRXB215 said:

@OffRoaderX I'm no expert but your situation sounds like it may be what's called "knife edge diffraction."

Don't try to overcomplicate everything.. It's just good line of sight..

[3cRadio]

6 hours ago, dosw said:

You think that's amazing, consider that with a handheld Yagi antenna an amateur can talk through the International Space Station's 2m/70cm (VHF/UHF) crossband repeater using a 5w handheld radio. Five watts, to reach a repeater hundreds, even a thousand miles away.

But what's different about the ISS? It's not that the repeater is a ham repeater. It's not that the repeater has some amazing antenna. It's not that it's got a million dollar radio. It's that there's nothing between you on the ground, and the repeater up in space. Line of sight.

So if you're able to reach a repeater 75 miles away reliably from an antenna that is 10 feet above the ground, that repeater's antenna must be at about 1050 feet above the ground between the two of you. Otherwise the curvature of the earth gets in the way. As an example, I can easily hit this repeater:

But I can hit it because I live at 1600m, the repeater is at 1700m, and everything between us is at 1200m. We have line of sight.

thanks for the reply!  pretty amazing that a 5w radio can make it up that far.  since earth has the whole coverture thing and obstructions, i can see why it might not go as far.

from what i can gather, the tower is probably approx. 2k ft elevation and i'm at 100 ft.  that image is pretty cool.  cant seem to find the site you were using but here's my google map image.  there are some hills but no huge mountains (from what i can tell).  

[WRXB215]

26 minutes ago, OffRoaderX said:

Don't try to overcomplicate everything.. It's just good line of sight..

Not only that, but I also misread your post.

[WRUU653]

Here is the line of sight tool. I know that area. That is a good reach for sure.

[WRTC928]

It's surprising how far you can communicate with a good line of sight. My personal best HT-to-HT is 22 miles, but we were both on elevated terrain features with apparently little or nothing between us. In Alaska, I had a cabin in a remote riverside location accessible (barely) with a 4WD vehicle. There was a lodge 12 miles away on a mountain that had phone service, and they monitored (as far as I could tell) every radio service known to man. When I got there, I'd flip on my repeater and check in with them. I couldn't directly communicate with an HT because of the trees, but by running an antenna into a tall tree, I could reach the repeater and thence the lodge from any reasonable distance with my HT. On the other side of the valley, some 60+ miles away, people on another mountaintop could talk to the lodge easily with an HT. I don't know how far a UHF signal has to go before it begins to degrade just due to distance, but it's a long way. Theoretically, it would be readable forever, but a radio wave isn't perfectly coherent. It will eventually begin to spread and scatter from things as minor as water vapor or dust in the air.

[WRYZ926]

UHF can go a very long ways as long as there is a clear line of site. 70cm is used all the time to communicate with satellites. Of course you don't have to fight the curvature of earth when talking to satellites.

A clear line of site is king when it comes to VHF and UHF.   

We have been having a lot of tropospheric ducting on GMRS over the last 2 weeks with the cooler than normal temperatures we have been having. I've been hearing a GMRS repeater located in Peoria, Illinois almost every day between 8:00 and 8:45 in the morning. Peoria is about 150 miles from me. I've also been hearing another repeater that is about 80-85 miles away.

[wayoverthere]

2 hours ago, WRYZ926 said:

A clear line of site is king when it comes to VHF and UHF.   

This sums it up well; i've talked into a GMRS repeater and a 70cm ham repeater on Joaquin Ridge on the west side of the San Joaqin Valley from a hill on the east side of the valley (75ish miles) with 5 watt HTs.  I've also talked into another 70cm repeater on Fremont Peak from a bit further east, around a 115 mile shot over the valley on the 50 watt mobile in my truck.  

In both cases, i had clear line of sight over the valley, as i was sitting around 4500-5000 ft elevation, and all of those repeaters sit around the 3000ft mark on hills/ridges.

[WSHH887]

I have to concur that line of sight makes a huge difference.  I live on a peninsula that sticks out far enough into the pacific ocean that I can pick up a repeater in Chula Vista, Ca.  That's pretty close to 200 miles.  It isn't always happening, but some times.  It actually took me a bit of detective work to figure out where it was.  I was flat amazed.  But, I sit on top of a hill and there are no obstructions between me and the repeater.  

I have that repeater programmed just the novelty of it.

[WSFN233]

I can open the Blue Mountain repeater from my home in VA thats roughly 62 miles away using a 5 watt Baofeng  UV-5RTP with the OEM rubber ducky antenna. This is from inside my home. The height/quality of the repeater seems more important than whatever hardware I'm running.

[WRYZ926]

9 hours ago, WSFN233 said:

I can open the Blue Mountain repeater from my home in VA thats roughly 62 miles away using a 5 watt Baofeng  UV-5RTP with the OEM rubber ducky antenna. This is from inside my home. The height/quality of the repeater seems more important than whatever hardware I'm running.

Have you tried to talk to anyone on that repeater?

Just because you can open up a repeater does not mean you have a strong enough signal for others to hear you clearly.

We have one guy that uses a hand held radio connected to a 6 inch Midland MXTA51 antenna mounted in the center of his Cherokee roof. He can often open the repeater but his signal is not strong enough for us to actually hear him.

[WSHH887]

No, I haven't. I just thought it was a hoot to receive from that far away. I'll give it a try next time I hear it. 

[WSFN233]

On 9/3/2025 at 8:49 AM, WRYZ926 said:

Have you tried to talk to anyone on that repeater?

Just because you can open up a repeater does not mean you have a strong enough signal for others to hear you clearly.

We have one guy that uses a hand held radio connected to a 6 inch Midland MXTA51 antenna mounted in the center of his Cherokee roof. He can often open the repeater but his signal is not strong enough for us to actually hear him.

I can open the repeater and receive fine from home.  I'm on the other edge of its/my capabilities though. If I drive 10-15 minutes east, I lose it.

[WRUE951]

 Its not unusual at all.  My repeater talks to Lone PIne users all the time. Thats 75+ Miles   A nearby repeater on a 4,300' mtn top talks 125+ miles..  Being in the Desert with long  open valleys makes a huge difference..   

[OffRoaderX]

29 minutes ago, WRUE951 said:

 Its not unusual at all.  My repeater talks to Lone PIne users all the time. Thats 75+ Miles   A nearby repeater on a 4,300' mtn top talks 125+ miles..  Being in the Desert with long  open valleys makes a huge difference..   

Last year I was in my Jeep using my XTL5000 in the desert outside of Barstow and was talking to some guys that were at Mengal Pass above Death Valley.. They were coming in loud and clear like they were right next to me.

[WRUE951]

32 minutes ago, OffRoaderX said:

Last year I was in my Jeep using my XTL5000 in the desert outside of Barstow and was talking to some guys that were at Mengal Pass above Death Valley.. They were coming in loud and clear like they were right next to me.

 

33 minutes ago, OffRoaderX said:

Last year I was in my Jeep using my XTL5000 in the desert outside of Barstow and was talking to some guys that were at Mengal Pass above Death Valley.. They were coming in loud and clear like they were right next to me.

Were you talking on a repeater?    I talked to someone two summers ago in Ballarat, Jeeping in Pleasant Canyon at Beater Mine. Thats about 80 miles..  They said they were at 4800 feet..  That woiuld have been a line of sight shot for my repeater.  The furhest i've talked towards death valley.  

[OffRoaderX]

15 minutes ago, WRUE951 said:

Were you talking on a repeater? 

Nope! We were on Simplex Ch19 ... Mengal Pass is around 4500ft and we had good line of sight.. i think it was around 80 miles or so.

[WSEZ864]

Kind of 'apples to oranges', but I often used my 50 watt 2 meter truck radio on a small hilltop near Lake Anna, VA to talk to the 147.300 Mt Weather repeater in Bluemont, VA about 70 miles away.

From home, where I had a home made ground plane antenna about 75 feet up in a tree, I could hit the same repeater with a 5 watt HT and it was actually a couple miles further. It is ALL about relative elevations and resulting lines of sight.

[WRYZ926]

4 hours ago, WSEZ864 said:

From home, where I had a home made ground plane antenna about 75 feet up in a tree, I could hit the same repeater with a 5 watt HT and it was actually a couple miles further. It is ALL about relative elevations and resulting lines of sight.

Yes it is. 

Our club's repeaters are 22.5 miles away (straight line) with the 2m and 70cm antennas at 900 ft and the GMRS antennas at 400-450 ft.  I can get into the 2m repeater with a HT from anywhere in my yard, getting into the GMRS repeater depends on where I am at in the yard and if I am facing their the tower's direction. I can't get into the 70cm repeater at all with a HT.

I have a 2m and 70cm faraday cloth j pole antenna. The 70cm is also good on GMRS. I ran both antennas to the top of a 21 foot tall telescoping mast and had no problems getting into all three repeaters with both HT's. In fact everyone thought I was on my 50 watt base radios.

All it took was getting the antennas up in the air.

I was stationed at Ft Irwin in the mid 90's and we used commercial radios for day to day use. All of the live fire ranges were on the north side of base and the Granite Mountains operated the live fire area from the rest of the base. We had to use relay systems to talk to main base when at the live fire ranges. Yet get to the top of the pass in the Granite Mountains and we could talk for a long distance with those commercial HTs.