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  #1 (permalink)  
Old 11-06-2018, 2:58 PM
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Default Ski Hill - Cross band Repeater Set Up

Hello,

I am an avid downhill skier and have skier friends who are HAMís as well. We have enjoyed using our HT radios to stay connected on the mountain but find that the lack of power of using HTís is sometimes an issue. So I am going to be setting up a cross band repeater using a mobile radio. This being said, I wanted to get some feedback from the community as to what frequency to use and how I should set this up.
Details below:

Mobile Radio: TYT TH-9800 Quad Band with cross band repeat function
Dual Band Mobile Antenna is cut for 145-165/430-467 MHz and is 18 inches in length from Powerwerx

HT: Dual Band TERA TR-505
Antenna: Stock Whip

Assumptions:
My mobile will be at the base of the hill in an open space (parking lot) with a clear view of the top of the mountain. Both HT would be anywhere on the mountain at any given moment, i.e. summit-base, base-summit, summit-summit, etc.

My questions are as follows:

1. Should I set up a channel on my HT to transmit DUPLEX on UHF or on VHF? Obviously, I would be receiving on the opposite band then the TX.

2. Should I set up my HT to also include a DUPLEX channel matching the Cross band repeater frequency split so that if I could not reach my Cross band repeater (no line of site), I could still communicate with my friend without him having to change channel? Would this not cause two signals to be transmitted at the same time being out of phase with each other?

3. Since I am outdoors, is it better to take advantage of the VHF signal strength with the lower power HT and use the higher power of the mobile to re-transmit at UHF to get better coverage on the mountain?

4. Finally, what VHF and UHF Frequency pair should I be using considering my antennas? I am located in Canada.

Your input in this would be greatly appreciated!

73's
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Old 11-06-2018, 3:41 PM
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Quote:
Originally Posted by Ve2nlm View Post
Hello,

I am an avid downhill skier and have skier friends who are HAMís as well. We have enjoyed using our HT radios to stay connected on the mountain but find that the lack of power of using HTís is sometimes an issue. So I am going to be setting up a cross band repeater using a mobile radio. This being said, I wanted to get some feedback from the community as to what frequency to use and how I should set this up.
Details below:

Mobile Radio: TYT TH-9800 Quad Band with cross band repeat function
Dual Band Mobile Antenna is cut for 145-165/430-467 MHz and is 18 inches in length from Powerwerx

HT: Dual Band TERA TR-505
Antenna: Stock Whip

Assumptions:
My mobile will be at the base of the hill in an open space (parking lot) with a clear view of the top of the mountain. Both HT would be anywhere on the mountain at any given moment, i.e. summit-base, base-summit, summit-summit, etc.

My questions are as follows:

1.Should I set up a channel on my HT to transmit DUPLEX on UHF or on VHF? Obviously, I would be receiving on the opposite band then the TX.

2.Should I set up my HT to also include a DUPLEX channel matching the Cross band repeater frequency split so that if I could not reach my Cross band repeater (no line of site), I could still communicate with my friend without him having to change channel? Would this not cause two signals to be transmitted at the same time being out of phase with each other?

3.Since I am outdoors, is it better to take advantage of the VHF signal strength with the lower power HT and use the higher power of the mobile to re-transmit at UHF to get better coverage on the mountain?

4.Finally, what VHF and UHF Frequency pair should I be using considering my antennas? I am located in Canada.

Your input in this would be greatly appreciated!

73's
I would use UHF from the portable to the repeater, counting on the better antenna and RF section to help the UHF. (Which will carry better during the winter, than it does in the summer.)

Consider your repeater location and the characteristics of the antenna. If your antenna angles the signal up from the horizontal, and it is placed near the peak, you will have less than optimal coverage. (A dual-band beam might be useful, if the beam pattern is not too narrow.)

The frequencies to use would depend on your location; do some scouting of the area, monitoring the possible frequencies for other users. Stay away from the weak signal, and satellite, allocations.

Having the reverse split programmed could be useful, but not used on a regular basis. In fact, having the control lock on would be smart, while skiing.

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Old 11-06-2018, 5:30 PM
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I would run the TH-9800 in low power mode and put a 120mm fan running continuous on the heatsink. If it gets used a lot it will overheat at high power very quickly. I run a Yaesu FT-8900 on low power cross band with an extra fan and it will transmit forever without overheating.

I would also choose my frequencies so they are not harmonically related as in whatever you use for the 2m side, make sure the UHF side is not exactly 3X that of the 2m frequency. An example of this might be 145.600MHz on 2m and 436.800MHz on UHF. The harmonics from the 2m transmitter will interfere with the UHF receiver.

Is this going to be used near Mont-Tremblant? I spent a month there once, very beautiful place.
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Old 11-06-2018, 6:28 PM
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.
.
Hey VE2
.
.
I think crossband repeaters are a blast. There is a fellow at the other end of my (Colorado) valley -in the mountains- that has one on 146.52 with a 420 Mhz input--- that thing covers clear to New Mexico. I listen to it all the time for Summits on the Air (SOTA) activity. It isn't a closed machine, but he is a tad chary about the input frequency. You should be too.
.
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At my home in Colorado I have imitated him with a similar crossband setup. Its not on ham radio- rather a 151/450 setup. We have several Land Mobile frequencies as a working ranch-- and I use a (mystery) transceiver as the crossband repeater (that will remains a mystery here since it may- or may not - be FCC type accepted for these services - people who know me know what if it is )
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Our primary ranch channels are in the 450 band. We have several in high band VHF (150-174Mhz) as secondaries. The crossband repeater listens on 450, and retransmits on 151. Normally 151 is never listen'd to or transmitted on- but its range and coverage *seems* to be superior to UHF.
If I can summarize, I would use UHF for your unit to unit simplex comm's. Switch over to VHF if the signals get spotty. Let your mobile machine happily idle away, rebroadcasting in VHF your 440 signals, but only switching over to it when things get scratchy. Of course choose off-used simplex channels, and maybe use PL tones (446.1/147.58 ?...just a suggestion )
.
You have a great idea and I think a very workable one. A Plus is that it will provide you and all your ham friends some interesting radio experiences (ie; "Experiments" - but hey, isn't that what this hobby is all about ? )
.
Do let us know how it all works out.
.
.
Lauri
.
.

Last edited by Lauri-Coyote; 11-06-2018 at 6:32 PM..
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Old 11-06-2018, 6:38 PM
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I will add to this. I typically take a UHF repeater with me skiing though Iím making the transition to VHF. 10W down in the parking lot has successfully covered Sipapu, Ski Apache, Wolf Creek, Monarch, and a few others.


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Old 11-06-2018, 8:07 PM
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I'd try upgrading the antennas first.

I can't even begin to describe what a performance boost a good antenna provides.. We're not talking about a little thing here, its like having a whole new radio.
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Old 11-06-2018, 8:26 PM
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Quote:
Originally Posted by Murphy625 View Post
I'd try upgrading the antennas first.



I can't even begin to describe what a performance boost a good antenna provides.. We're not talking about a little thing here, its like having a whole new radio.

A high gain antenna may actually have a negative effect on coverage, a simple 1/4 wave or 1/2 wave is probably going to be your best bet.


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Old 11-07-2018, 10:50 AM
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Quote:
Originally Posted by Project25_MASTR View Post
I will add to this. I typically take a UHF repeater with me skiing though Iím making the transition to VHF. 10W down in the parking lot has successfully covered Sipapu, Ski Apache, Wolf Creek, Monarch, and a few others.


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You have a UHF repeater or a crossband repeater?
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Old 11-07-2018, 10:55 AM
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You may have better luck with a UHF repeater. Easy to build. No Ground Plane antennas work well, and you donít need a ton of power. 10w into the duplexer will give you pretty balanced coverage.


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Old 11-07-2018, 2:06 PM
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Quote:
Originally Posted by kayn1n32008 View Post
You may have better luck with a UHF repeater. Easy to build. No Ground Plane antennas work well, and you donít need a ton of power. 10w into the duplexer will give you pretty balanced coverage.

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Thanks for your suggestion but I will stick to the equipment that I have and avoid building a "real" repeater. That will be a different project

As of now, I will set my HT to transmit on UHF since the small antennas will probably perform way better this way.

My consensus is:

Mobile: I will use the Cross band Repeater to TX on VHF.
HT: If I cannot hit the C/B Repeater with my HT on UHF, I will attempt to TX simplex with the other HT's in my group on the C/B Repeaters freq pair using the reverse split frequency pair on a seperate channel on my HT i.e. HT TX = C/B TX

Does this make sense?

Thanks
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Old 11-07-2018, 2:12 PM
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While that might workóand I don't see why not to give it a try as a fun projectóit's worth noting that terrain (and the line-of-sight nature of the bands involved) is more likely to be a limiting factor than power. I'm admittedly not much of a ham geek, but I am a ski-race coach (and have been a patroller and such), and most of the radios I've used at work had both repeater channels (usually one or two that the mountain used for ops and patrol) and simplex channels (which we'd use for running races, sharing course reports, etc).

Most of the time, the mountain repeater ends up up the mountain, not at the base, so that it can "look down into" various terrain features, and the simplex comms work fine most of the time on the same trail or trail pod, but not so much when a ski area "wraps around" a mountain and people are on opposite sides.

I'd definitely keep terrain in mind while parking, and depending on how much effort you want to put in, consider a full-wave antenna used only while stationary in the parking lot.
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Old 11-08-2018, 12:47 PM
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Ya, I definitely think it is best to have the C/B repeater at the top of the mountain but that is not really feasible.
I will do some experimenting once the snow falls and report back.

Is it worthwhile getting an antenna analyser to help chose what frequencies I should be using?
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Old 11-08-2018, 12:54 PM
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Default Ski Hill - Cross band Repeater Set Up

Good luck!

As prcguy stated(I think) make sure you choose a UHF frequency that is not the 3rd harmonic of your VHF frequency.

Depending on your band plan, use an uncommon simplex VHF frequency and an uncommon simplex UHF frequency. With out having a full repeater, there is little point in using a split pair on either VHF or UHF.

I use 146.4150MHz with a 156.7Hz PL for VHF and 446.1500MHz with 156.7Hz PL for UHF when I cross band.

I strongly recommend using PL on both encode and decode on both frequencies, and make sure you have a time out timer set on the cross band repeater.

Edit: Depending on how much the mountain rises above the parking lot a simple VHF 1/4 wave antenna may work just fine. A 1/4 wave VHF antenna is resonant as a 3/4 wave antenna on UHF. It has a funky high takeoff angle, which may be just the ticket for your situation.

Also, keep your transmitter power(on both VHF and UHF) to 5-10w. This will keep the heat generated down and extend your battery life. For a battery, look in the 55-75AH range to ensure you do not over discharge the battery over the course of a day on the hill

https://www.cdnrg.com/products/D12750

I have used these for years doing RTK surveying with a 35w UHF datalink radio and never had any issues going 1-2 days between charges.
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Last edited by kayn1n32008; 11-08-2018 at 1:05 PM..
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Old 11-08-2018, 12:54 PM
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Quote:
Originally Posted by kbroderick View Post
While that might workóand I don't see why not to give it a try as a fun projectóit's worth noting that terrain (and the line-of-sight nature of the bands involved) is more likely to be a limiting factor than power. I'm admittedly not much of a ham geek, but I am a ski-race coach (and have been a patroller and such), and most of the radios I've used at work had both repeater channels (usually one or two that the mountain used for ops and patrol) and simplex channels (which we'd use for running races, sharing course reports, etc).

Most of the time, the mountain repeater ends up up the mountain, not at the base, so that it can "look down into" various terrain features, and the simplex comms work fine most of the time on the same trail or trail pod, but not so much when a ski area "wraps around" a mountain and people are on opposite sides.

I'd definitely keep terrain in mind while parking, and depending on how much effort you want to put in, consider a full-wave antenna used only while stationary in the parking lot.
Depends on the layout of the resort. When a backside is present, you need something on the ridge or overlooking the whole resort. Smaller resorts, repeaters tend to work well down in the parking lots.
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Old 11-08-2018, 1:01 PM
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Quote:
Originally Posted by Project25_MASTR View Post
Depends on the layout of the resort. When a backside is present, you need something on the ridge or overlooking the whole resort. Smaller resorts, repeaters tend to work well down in the parking lots.
Ya, this resort is quite small. Not much of a back side but several peaks.
It is called Bromont. I have attached the Map.
I will be setting up the C/B Repeater at P1 parking lot.

I mainly ski the Mont Brome peak.
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Old 11-08-2018, 1:26 PM
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I have used this site to help with predicting coverage. very cool tool made by a fellow French canadian HAM.
Radio Mobile Online
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Old 11-09-2018, 2:22 AM
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Originally Posted by Ve2nlm View Post
Is it worthwhile getting an antenna analyser to help chose what frequencies I should be using?
Not really. The analyzer would tell you about your antenna, not the frequencies in use in the area. For that, you want some type of spectrum analyzer, which can be done with small computer and an RTL-SDR.

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Old 11-09-2018, 6:53 AM
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Originally Posted by krokus View Post
Not really. The analyzer would tell you about your antenna, not the frequencies in use in the area. For that, you want some type of spectrum analyzer, which can be done with small computer and an RTL-SDR.

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I meant to use the analyser to check what frequencies work best for my antenna.

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Old 11-09-2018, 7:07 AM
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Your 18 inch PowerWerx dual-band mobile antenna is going to be very broad, allowing you the use of a wide range of freqs in both the 2M and 70 cM bands. Stay away from not only 3rd harmonic between 2M and 70cM, but also satellite input freqs, common repeater inputs, and repeater control links.
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