Radio Antennas

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jj
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Radio Antennas

Postby jj » Mon Apr 29, 2013 9:26 pm

Our radios have good range when everyone is up at altitude but range is very limited if you and your retrive team are both on the ground. Even with one on the ground the range decreases significantly.

The radios are all good. It is the antennas that are garbage. All handlheld radios come with cheap, bad rubber ducky antennas. They barely work and even worse, they are not tuned for our frequencies.

Even if you use the rubber duck antenna while in the air, you should consider getting a Comet SMA-24 flexible antenna to use once on the ground. It will likely quadruple your transmit and receive range. The whip is so flexible and thin you can even use it while flying and it also works on the 70cm band too. If you want something shorter, at 8" long you can get the Diamond SRH519. Thin and only a little longer than the stock antenna but twice the range and reception. Your signals will be clearer too. Either of these are big performance upgrades to your handheld radios and they cost $25. If you have a Baofeng radio then head to Ham Radio Outlet and buy a SMA-23 female to female converter for $4 and you can use any of these good antennas. The Baofeng is a good radio but its antenna is the worst of all.

For really good XC range you can build or buy a 1/4 wave dipole out of coax but most of those have very narrow frequency band and aren't all that good depending on their tuning (still far better than the stock antennas). The best way to make those is to use 1/2" copper tape that has eight times the bandwidth and far more gain, but any dipole should also have a balun or ferrites to keep from over heating the output section of your transmitter (you can get some at Radio Shack). Without them you are really only transmitting at partial power as the signal reflects back through the unbalanced coax cable. While they are great in the air they don't do you much good if you are trying to be heard on the ground walking around with your radio with the antenna attached to a harness laying on the ground. You want the antenna as high up as you can get it while transmitting.

BTW I use a little dab of goop or a few wraps of electrical tape at the base of the antenna elements for mobile radios to minimize the chance of breaking them if you drop the radio. This goes at the junction of the element and the base of the antenna (part that screws onto the radio).

If you use a radio with an antenna inside the car your range is going to be horrible as your are sitting in a Faraday cage that is soaking up the signals. Either get a magnetic mount antenna to put the antenna outside the car or go for a permanent mount. I use a mount with a shorter 18" antenna for normal use (SS460SB) and switch to the longer antenna (38" Diamond NR770HB) when I need to reach out 30-40 miles to hear Darren on the other side of the dunes and relay his location. I could hear him with either, but when I went to the longer antenna the signal strength and clarity were vastly improved.

Locally you can get things at Ham Radio Outlet in Denver on Evans about a mile West of Parker road. They also have mail order. They are also the only place I know of that has the female to female SMA converter that allows the Baofengs to use normal SMA antennas for $4.

On line ordering I've found some good deals at dxengineering.com and they are good on shipping and handling.

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Fred Kaemerer
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Re: Radio Antennas

Postby Fred Kaemerer » Wed May 01, 2013 6:49 pm

Dude,

My watch has a faraday cage. Maybe that's why I can't ever hear you for a retrieve. :D :D :D

F
Have an unstable day!

WW Sport AT, WW Falcon 3 Tandem, WW U2, ATOS VR, Partridge In A Pear Tree

Kiernan
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Re: Radio Antennas

Postby Kiernan » Wed May 01, 2013 7:43 pm

Thanks JJ. I'd like to upgrade my antenna. I notice my reception is poor plenty of times.

Reviews of the SRH519 on eham.net say that it's good but it's not rugged. That doesn't sound suitable for our use. Do you know another antenna with similar capabilities that's not as fragile? Is this the antenna you use?

What do you know about repeaters? Would that help at all with reception over longer distances in mountain XC flights?

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jj
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Re: Radio Antennas

Postby jj » Thu May 02, 2013 7:29 am

I just got a SRH519 recently so I can't say how durable it is long term, but it seems fine to me. The base is quite solid but like most antennas the connection between the base and element can benefit from a strain relief. By either adding a little goop at that junction or wrapping it tightly with some electrical tape it should be fine. I toss my old ducky antenna in the bottom of my harness in case the primary antenna would ever break, but I've never had any issues.

I've used the SMA-24s for years with no problems and I bend that antenna into loops. The SMA-24 works great but it is a little longer at about 16". It is so narrow and flexibile it probably is not an issue for most, and it has twice the gain of the SRH519. I really like the SMA-24.

I use repeaters and have them programmed into my radios. You need to use your ham call sign on them but they give you amazing range. Repeaters have longer high gain antennas so they pick up your signal much better than another handheld radio. They then take your signal and re-transmit it using a 50 or 100 watt transmitter. Re-broadcasting on the higher gain antenna would be alone good but use of a high gain antenna and 100 watts really gives you incredible range. Some repeaters are linked via the internet so they not only repeat, but send your signal to a remote repeater and have it re-broadcast there. Repeaters work by having an offset frequency. They receive on one frequency and transmit on another that is offset slightly. This is what the plus or minus offset option is on your radio channel options. Most repeaters also require a special tone to be sent at the start of transmission so that they don't get activated accidentally. Again, another option on your radio.

This is where radio programming software comes in handy. You can set this all up with the software and then upload it to your radios. NOTE: Repeaters are heavily monitored so you need to use your ham call sign, but again that is easy to get. Once you have it you can use the repeaters and have virtually unlimited range. I've used my handheld and with 5 watts get to a repeater up near Golden (with the SMA-24 antenna) and have talked to someone up in Boulder on the same repeater. Some repeaters repeat on both the 2 meter and 70 cm (440mhz) bands. If you use the 70 cm band your antennas are effectively 3 time longer. The $45 Baofeng radio is dual band and can use either. PM me if you want further info.

If you see me around on the hill I'll have the antennas with me. Otherwise I'll bring my radios and antennas to the next meeting if you want to check them out.

Kiernan
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Re: Radio Antennas

Postby Kiernan » Thu May 02, 2013 7:50 am

Next meeting is only two weeks away, it'll be great to see the antennas then.

Maybe it's time to look into getting a ham license to be able to use repeaters. Do both receiving and sending pilots need to be on the repeater? Can you still use DCS with repeaters?

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jj
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Re: Radio Antennas

Postby jj » Thu May 02, 2013 9:13 am

I'll bring things by at the next meeting.

Anyone in our club could easily get a ham license. The test costs $15 and you're set. I've seen 10 and 12 year olds pass the exam. You can practically guess your way to passing, so with a little on line studying it is no biggie.

You don't need a license and call sign to listen, but you do for transmitting. The regs are that you need to use your call sign when initiating radio work and again every 10 minutes or so, but that is all. Unlike the non-repeater frequencies that are empty, there is monitoring of the repeaters. Still they aren't used much except during early mornings or evening commutes.

No DCS on repeaters. It re-transmits so DCS doesn't work with a re-transmission. Can't lurk. Need the Ham license.

Colorado has linked repeaters that provide range from Cheyene to Pueblo and Limon to Grand Junction, including all along the I-70 corridor.

You can also use a linked repeater to connect to repeaters in other places like Atlanta, Phoenix, London, Capetown, Dublin.... It is like Skype but cheaper and its been around a lot longer. Someone could be flying down in Australia, or Crestline in CA, use a linked repeater and be on the radio with someone flying at Lookout. But no need for all that.

I see repeaters as being very useful when someone is planning on doing a long XC up and down the front range, or from lets say Wolcott to Boulder. Easy to keep in contact for a retrieve or in case of an emergency bail out landing. Since they are monitored, even if your retrieve doesn't hear about you, someone else probably will. Might be good to have set up just for emergency XC situations.

For example lets say I plan to go XC from Villa to Buena Vista. If I have a radio set up for using the repeater on top of Methodist Mtn at 11,700 ft., once I get out of normal radio range I could switch to the repeater frequency and effectively have a 100 watt transmitter and full wavelength antenna to use. My retrieve car can monitor both the primary and secondary channel (depending on radio) so they could switch to use the repeater once they hear me transmit that I've crossed Poncha Pass. So all I need to do is getting the flying part working and then I'll be set :roll:

On the other hand, seems like plenty of others in the club have already got the flying part worked out!


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