Here’s another test of the UV-3R in simplex, again with somewhat surprising results. This time, we tested comms between the UV-3R in the field, and my Yaesu FT-897D as the base station. The UV-3R again relied solely on its stock antenna. The FT-897D relied on a quarter-wave vertical with drooping ground-plane, mounted in the attic (because, despite my service as a member of its board of directors, I am unable to convince my benighted HOA that Radio is Good, which means you can’t have exterior antennas).
The antenna (which I made yesterday, and a full posting on that will be coming soon) showed an SWR of 1.3 at 446 MHz. It sits on a PVC mount I made, and is about 30 feet above ground level. Here it is, cunningly hidden in our attic, stealthily emitting its RF emanations, where no one can see:
I set the Yaesu to show two Watts on the power meter (so it would be putting out the same power as the UV-3R), left my XYL (who is KG4QFG) and our ten-year-old son at the base station, got on my bicycle, and proceeded to nearly kill myself (as ham radio is disgustingly good at turning middle-aged men like me into useless fatasses who can barely pedal to the end of the street before wheezing and gasping like a semi tractor-trailer coming to rest after a thousand-mile run). Full list of settings for both radios were: 446.000 MHz, simplex; 2.0 W rf out; 71.9 Hz CTCSS, Rx and Tx.
My son and I exchanged signal reports at a number of locations, with me trying to get far enough away (before collapsing into a puddle of Extra class embarrassment) to lose his signal. What we got surprised us, and is marked on the map after the link below…
This sat-photo is turned 90 degrees, so that east is up, and north is to the left. The arcs are drawn at one mile, two miles, and three miles from the base:
The red dot at the lower right is the base location (you can see a distance scale nearby). The green dots indicate locations where our tests read S9 or above on both signal meters. The yellow dots indicate signals less than S9. All locations were 100% readable. The yellow dots seem odd because they are within the one-to-two mile distance, whereas the readings from distances beyond two miles were all S9 or better. The local terrain is probably the reason, as that stretch of road dips down a fair bit. East of that stretch, there’s a lot less in the way of houses, trees, and whatnot. Still, these results kind of amazed us. You can see our best DX set out with the orange line on the right-hand side. We had full signal, both ways, at 3.5 miles with our setup. Note that that path is through a rather large building (Verizon’s Virginia headquarters) that is much taller than our house.
We’d have tried longer distances, but I was afraid I’d die if I had to return over anything greater (though my son did a great job of sustaining the old man, by deciding to advise that I fasten my seat-belt before each trip to the next stop, and predicting the amount of turbulence and interesting sites to be experienced on each leg of the voyage; he’s not that interested in radio, but he has a great imagination).
As tests go, this one is a bit odd, as it both tells us something remarkable, and also tells us very little. That is, we were surprised by the long distances we got, but we also would have liked to know where the signal began to drop off. The problem with that was that I hadn’t expected to be able to get two miles away, much less over three, so the map I took with me wasn’t big enough. Also, there’s that fatass factor, which kind of limits how far you can go…
The antenna was a couple of hours’ worth of work, made from some ordinary UHF connectors, RG-58, some PVC I got at Home Depot, and two coat hangers. Making it was easy. Tuning it was easy, too, but that also yielded a rather big surprise.
My next post will be about the antenna itself. (And, yes, I know it is almost heresy to build a single-band antenna for 70cm when the world is so thoroughly supplied with designs and products for dual-band antennas that work on 2m and 70cm, but I wanted something optimized for the one frequency I wanted to use, and something that would be easy to make. I got what I wanted, so two meters can just wait for another day.)