KG-905G Disappointing Short Distance Test

Hi…

I am new to GMRS. I recently purchased two Wouxun KG-905G HT radios (buytwowayradios.com), replacing the stock antennas with the Nagoya NA-771G. I reside in a suburban subdivision. For my initial test (running 5w on Ch 5), I took one radio to a 3rd floor unit in a building 0.9 miles away, per Google Maps (a bit shorter as the crow flies). I expected a clear signal at that distance, but was not the case. My TX’s were not received by the 3rd floor unit. Their TX’s were hit or miss. Some came through (with static), others did not.

The only impediment I can really think of is a line of those massive overhead electrical power lines that cut across the two locations.

Would that be enough to knock out a signal between these relatively short distance locations? Any suggestions to improve communications?

Obviously, a disappointment starting out.

Thanks in advance.

Those power lines can be very disruptive. However, a lot can depend on how good the “other guy’s” radio is as well. What was he/she using, same thing, or something else? The 905G is a pretty good radio so it’s worth the ask. Try other locations in the house and try going outside to see if it improves. Being inside a home can really do flaky things. Very easy and inexpensive to put a $30 antenna outside the house, run a coax inside, and (with an adaptor) connect it to your handheld. I bet that would improve things dramatically. (Recommend the same if you wish to use it in your car. With a mag-mounted antenna on the center of the roof, and the coax run inside to the driver’s compartment, performance increases dramatically.)

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UHF/GMRS is line of sight. Being inside of a building can definitely affect your signal TX and RX. I have those radios and have been happy with them. You might try having both radios outside and try different distances moving away from each other. Also, try using the original antenna just to make sure there isn’t a problem with one of they other antennas. You could try using different channels as well. There are a lot of variables that can change TX and RX characteristics. I live near some big power lines and have had any problems. I worked in a power plant for almost 40 years and never had issues with UHF or VHF. I’m sure other folks will add to this. Let us know how it goes.

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Firstly, I agree to check the stock antennas. I have spent thousands on aftermarket antennas and have only found one that was only slightly better than the antenna that comes with the radio. Most were worse, and many had very high SWR readings.

There is one manufacturer who goes through great lengths to explain about possible “counterfeit” antennas. I think they do that to excuse their poor performance and maybe raise the perceived “value” of their antennas. (“Must be great if everyone is trying to copy them.”) My opinion only, of course, but I like to test everything scientifically back-to-back, and measure actual SWR numbers while holding the radio in exactly the same way. (Just the position of your hand on a radio can dramatically affect SWR readings!)

The other issue is exactly how the antennas were placed. UHF is line of sight, and this means that anything blocking the antenna can compromise the signal. This includes trees, buildings, etc., but the surprising thing is that UHF is quite good at finding holes in vegetation and penetrating buildings through openings. (The wave length itself is quite short.) But the number one absorber of RF waves in the UHF spectrum aside from just plain distance, is the human body. If you wear the radio on your belt, you can be 1/2 mile away, and the signal drops out completely just by turning so that your body is between the antenna and the transmitting radio. (Try it for yourself.)

My final point is that perhaps your expectations are too great. A mile is stretching it for any VHF or UHF radio, let alone one in real-world conditions. If you could find a way to eliminate the curvature of the earth and all the obstacles in between as an issue - as in, standing on one mountain top and talking to another mountain top - one could conceivably get many miles in range. In real world conditions, range can be as short as 1/4 mile.

Interesting trivia time. Did you know amateur radio operators on handheld radios have actually talking to the International Space Station when it was overhead. This was on the VHF frequency of 145.800MHz, and this shows how radios communicate through line-of-sight when there is literally NOTHING in between the antennas but sky and space.

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Spoke to an astronaut years back in Skylab - perfectly clear and as if next door, until he dropped below the horizon and he just snapped out mid sentence!

Buildings nowadays are also partial Faraday shields - concrete with rebar makes a great shield. The thing with low power radio is it’s short range and often VERY short range. Sometimes hundreds of yards. The skill in radio operating is in moving radios - up/down/left/right/rotate to improve signal to noise. You might find that one spot, standing on a chair, with your arm up in the air where the path becomes clear - and if the person the other end does the same - it’s workable. If either of you move, it dies.

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Metal parts of buildings like metal studs, building materials etc can cause a lot of distortion. I have a Yaesu FT65R which is a VHF/UHF walkie talkie and outside my house I can hit the repeater 9 miles away and talk all over the area. So as far as the radios go, a good quality one with a good quality antenna will transmit well. GMRS is not far outside the UHF ham band and should work unless there are a lot of obstacles. Inside the building may prove to be a challenge but move around a little and see if that makes a difference. You might be able to identify what is causing the signal block.

I’d recommend a Smiley Antenna tuned for GMRS. The Nagoyas are totally overrated, IMHO. That might give you a fighting chance.

My tests suggest the Nagoyas are pretty poor antennas - usually worse than the stock ones that come with the radios.

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Firstly, from any VHF/UHF radio…forget about how many miles, your range is line of sight plus about 10%.
So your friend may be less than a mile away, but if that is in the bottom of a valley, or surrounded by tall buildings, you’re going to have problems.
Re antennas, well you must realise Nagoya’s are the most counterfeited antennas out there, it gets worse when you realise most of them are knock off copies of Diamonds to start with.
I recently bought 5 “Nagoya” antennas, from different suppliers & put them on my analyser …
Two were open circuit…no connection at all from the centre pin…
Another two were clearly fakes, poor quality printing etc, but they did “Work” just not on the 2m & 70cms bands they were supposedly designed for…so only 1 actually worked anything like the original Nagoya i bought back in the mid 90’s.
A point to note, i bought a cheap Baofeng a couple of years ago and it’s dual band aerial is excellent so don’t be so quick to discount manufacturers stock antennas.
Oh and yes power lines often cause issues if they’re close enough but it depends on many things, the frequencies in use, voltages and frequency of the lines etc, but every country has its own regulations about interference & its unlikely the power lines near you are not compliant, chances are hundreds of radio users locally would’ve noticed and reported their issues to the authorities to get resolved.
I’d try the same experiment from different locations, can you get to the roof?
Does your building have, for example, those reflective, silvered windows?
Lots of things could be the issue. Trouble is we get spoiled by the cell phone network and think radio is going to be the same…well it could be if we had phone type repeaters every couple of miles…but uhf radio is not like that, it just takes the guy you want to talk to to be in the shadow of a building and your stuffed.
I’ve worked from Uk to Germany on 1/2 a watt…but am totally unable to work my friend 3 miles away on 50 watts, some days i can chat to a friend 30 miles away with no difficulty, others absolutely nothing…that’s radio for you…
Good luck and keep experimenting

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Interesting, i worked MIR a few times back in the day, but of course that is down again to their line of sight being huge, not a lot of obstacles between them and us.
And yep who knows what is in his and his friends building walls, i mentioned in my reply those silvered reflecting windows can do a great job of reflecting signals too, same with plaster boards, sheet-rock i think you call them, some of them have foil backing, then the aluminium studding, wiring, as you say re-bar, all shield the user from radio

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