A head scratcher - long distance repeater access through a mountain

[Sbsyncro]

So I travel up and down the coast of CA so I programmed my KG-1000G with a bunch of the open repeaters on my routes so that I can possibly use them while traveling.  After I finished the programming I found that I was able to hit the nearest one (almost 70 miles away) and talk to the person there. I was frankly baffled. (He confirmed his location in San Luis Obispo, which is on the other side of the tower from me).  I plan to do a bit more testing to confirm that it wasn't a fluke, but how would one explain the ability to talk to a repeater 70 miles away and through a 2,700' mountain? I'm basically at sea level and the tower is about 1300 feet.  It is operated by Rugged Radios, apparently.   I'm on a Wouxun KG-1000G with a Midland 6db antenna mounted to the roof rack of my Jeep.

 

[kidphc]

So I travel up and down the coast of CA so I programmed my KG-1000G with a bunch of the open repeaters on my routes so that I can possibly use them while traveling.  After I finished the programming I found that I was able to hit the nearest one (almost 70 miles away) and talk to the person there. I was frankly baffled. (He confirmed his location in San Luis Obispo, which is on the other side of the tower from me).  I plan to do a bit more testing to confirm that it wasn't a fluke, but how would one explain the ability to talk to a repeater 70 miles away and through a 2,700' mountain? I'm basically at sea level and the tower is about 1300 feet.  It is operated by Rugged Radios, apparently.   I'm on a Wouxun KG-1000G with a Midland 6db antenna mounted to the roof rack of my Jeep.
 

Localized tropospheric ducting.. or incredible repeater setup with a good line of sight to you.

One tropo event we were talking to people in NY, about 275 miles from the repeater. Only last 30 minutes but was awesome.

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[Sbsyncro]

2 minutes ago, kidphc said:

Localized tropospheric ducting.. or incredible repeater setup with a good line of sight to you.

One tropo event we were talking to people in NY, about 275 miles from the repeater. Only last 30 minutes but was awesome.

Sent from my SM-G975U using Tapatalk
 

Based on the 2700' mountain between us, there is no LoS, unless I misunderstand that term.   As to atmospheric ducting, I was able to make contact again a few days later and plan to try again today to rule that out.  When I make contact, I'm going to ask them more about their setup.  Maybe they have a 1,000' tall tower.  

[kidphc]

Based on the 2700' mountain between us, there is no LoS, unless I misunderstand that term.   As to atmospheric ducting, I was able to make contact again a few days later and plan to try again today to rule that out.  When I make contact, I'm going to ask them more about their setup.  Maybe they have a 1,000' tall tower.  

Could be. I get to a repeater that is about 45mi on 70cm. Was surprised to hear it in the mountains of wva, about 85 miles at point.

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[n4gix]

There is also the possibility of "knife edge diffraction..."

[MichaelLAX]

How do I access that map?

I am located in the flats of The San Fernando Valley and with my rooftop Comet tri-bander, I am able to consistently hit a 70 cm Ham repeater on Double Mountain about 90 miles away in the Techachipi Mountains. It is part of the Kern Emergency Radio Network.

So I am going past the Los Angeles National Forest and further past Frazier Mountain to be able to hit this repeater.

Actually its frequency is shared with another repeater that I can hear to the South on the PAPA network, so when I want to chat on KERN, I more consistently use the Frazier Mountain Repeater.

But I would love to use that map to see how I am able to do this.

Another example is the Ham 2 meter Catalina repeater on Catalina Island.  I can use it consistently even though the Santa Monica Mountains are in between.

So there is some sort of "bending" effect that allows me to use these repeaters using my Anytone AT-779UV with 20 watts.

Do you ever stop at Jocko's in Nipomo for their Oak-fired Spencer Steaks? Hmmm: The Best!

[wayoverthere]

Makes me wonder how spot on the repeater location is on the map,  and how high up the repeater is. If it's on a high enough hill, or mapping off a little bit from it's actual location, you may in reality have LOS.

I've been able to hit one near Coalinga on high power with a little 5/8 wave on a bookcase indoors (estimated 60ish miles), and from up in the sierra nevada foothills managed to get into another 70cm repeater in the same area (CARLA#15, 75ish miles from where I was) on a 5 watt HT.

[marcspaz]

You're probably experiencing scatter, diffraction and refraction.  Think of it like sunlight. Where an object blocks the sun, there is not pure darkness. In fact, it can still be fairly bright and as you get further away from the object, the more sunlight is seen. Well, due to radio waves bouncing off of dust, moisture and debris in the atmosphere, combined with other elements redirecting the signal, it's very possible and common.  If the weather and geomagnetic conditions are fairly stable, it can be very repeatable, too.

[DONE]

6 hours ago, n4gix said:

There is also the possibility of "knife edge diffraction..."

Yep, thinking the same thing.

 

[Sbsyncro]

21 hours ago, MichaelLAX said:

How do I access that map?

www.gaiagps.com - its free unless you want multiple map layers.  Draw a route using straight line mode.

Quote

Do you ever stop at Jocko's in Nipomo for their Oak-fired Spencer Steaks? Hmmm: The Best!

Yes!  Although I recently heard that they didn't make it through COVID lockdowns are are now out of business, sadly.  I have not confirmed this.

[MichaelLAX]

Thanks!

The news about the closing of Jocko's is very sad 

Here is the map from me shack to the KERN Double Mountain Repeater.  Turns out it is only 60 miles:

 

[donniefitz2]

I don't think this is unheard of. I can talk on the Tucson 650 from where I'm located (N. Scottsdale). That's about 110 miles away and lot's of stuff in between. Although, I'm guessing that antenna is quite high. 

[MichaelLAX]

How many watts does your radio output?

[Sbsyncro]

How many watts does your radio output?

Rated for 50 watts


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[MichaelLAX]

Thank you: I was curious how many watts @donniefitz2uses to communicate with the Tucson 650 repeater 110 miles away?

I am guessing the repeater must be on Mount Lemmon. If so, its elevation is > 9,000 feet.

[donniefitz2]

35 minutes ago, MichaelLAX said:

Thank you: I was curious how many watts @donniefitz2uses to communicate with the Tucson 650 repeater 110 miles away?

I am guessing the repeater must be on Mount Lemmon. If so, its elevation is > 9,000 feet.

I can do it with my DB20G (ever heard of it ) and various other radios I've tried from my base setup. I can hit it around town mobile, but I need high wattage then. The 1000G can do it in my truck. Yeah, that 9,000ft is the reason, but it still blows my mind. 

[Sbsyncro]

FWIW, I just made contact again with the same repeater and talked to the same person again.   We chatted about how curious it was that we were able to have such good quality comms considering the distance and mountain range in between us.  I also confirmed the general location of the repeater.  the Rx signal on my side was very good with some static, but I had no problem hearing the other party very clearly.  3/5 bars on my KG-1000G whatever that means.

[wayoverthere]

29 minutes ago, Sbsyncro said:

FWIW, I just made contact again with the same repeater and talked to the same person again.   We chatted about how curious it was that we were able to have such good quality comms considering the distance and mountain range in between us.  I also confirmed the general location of the repeater.  the Rx signal on my side was very good with some static, but I had no problem hearing the other party very clearly.  3/5 bars on my KG-1000G whatever that means.

I wonder if it was the Steve with Rugged Radios I've seen popping up in some of the Facebook gmrs groups.

[Sbsyncro]

24 minutes ago, wayoverthere said:

I wonder if it was the Steve with Rugged Radios I've seen popping up in some of the Facebook gmrs groups.

No, I asked.  it was the owner of SLO700 - another nearby repeater, who monitors both repeaters.

[wayoverthere]

38 minutes ago, Sbsyncro said:

No, I asked.  it was the owner of SLO700 - another nearby repeater, who monitors both repeaters.

Good deal. Stuff to keep in the back of my mind for next time I'm out that way.

[MichaelLAX]

12 hours ago, donniefitz2 said:

I can do it with my DB20G (ever heard of it )...

I am consistently amazed at the efficiency of this $109 radio! 

Now if they would only come out with the DB50G! 

[tweiss3]

 

[Sbsyncro]

Interesting read, but the weird thing (the "head scratcher", if you will), is that I can contact this particular repeater any time I want.  It is not behaving like some rare atmospheric "window" that allows a brief period of refraction/deflection of the signal.  I've done it on a sunny, cloudless days and on a partially overcast days. (never was it foggy). 

Now my line of sight situation is not as dramatic as that post by MBRUN you quoted, but it still looks "impossible" on paper...   Its pretty interesting to me that I can jump on and talk with this repeater any time I want with good signal strength on both sides...

[Lscott]

You sure you're talking to the repeater that you think you're using?

Some repeaters have remote receivers and transmitters. There is a "voting" system that will route the strongest signal to the transmitter from the various remote receivers.

Also are there any valleys or tunnels around or through the mountain? A valley could be "ducting" the signal around the mountain bouncing the signal off the valley walls. A large tunnel through the mountain could also function as a kind of wave guide at UHF. The later I've heard about where sailors on board large ships had no trouble picking up local FM stations deep inside while docked at a port. The steel passage ways through the ship acted like a huge wave guide at UHF.     

[IdahoJohn]

5 hours ago, Sbsyncro said:

Interesting read, but the weird thing (the "head scratcher", if you will), is that I can contact this particular repeater any time I want.  It is not behaving like some rare atmospheric "window" that allows a brief period of refraction/deflection of the signal.  I've done it on a sunny, cloudless days and on a partially overcast days. (never was it foggy). 

Now my line of sight situation is not as dramatic as that post by MBRUN you quoted, but it still looks "impossible" on paper...   Its pretty interesting to me that I can jump on and talk with this repeater any time I want with good signal strength on both sides...

I think the Santa Ynez and Santa Maria valleys may be part of the reason for this. 

 If you are in the city getting over the mountains would still be a factor, but I would think it very

possible from Camino Cielo. Could it be your signal is getting around Pt. Conception over the ocean?

I know the area well, I lived in the area for most of my life. so it's interesting that it is always possible

for you to make contact.