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.