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I have this radio, with a rubber duck antenna, and a repeater twenty miles away to my north-northwest. If I set my radio on the top of a cabinet in my bathroom, I receive the repeater fine. I can't hit it from there, but I can hear it, which for now is good enough. I can't receive that repeater anywhere else in the house, though, on that antenna. My house is off-grade, so my floor is about three feet above the dirt below. Therefore, on the bathroom cabinet, it's around ten feet above ground.

I have also a 4-element yagi. Currently, I have it on a makeshift 3/4-inch PVC mast shoved into a 5-gallon Firehouse Subs pickle bucket with a hole in the lid sitting beside my recliner in the den. Keep laughing, but it works. So, this thing is pointed pretty much right at that repeater, a foot from my ceiling, so about the same altitude as the rubber duck in the bathroom, and nothing. I get bupkis. But wait...

I take the antenna off of the radio, and put on the radio a BNC tee. On one side of the tee, I put my antenna. On the other side, I put another tee, which itself has a BNC 50-ohm Ethernet terminator on each side (scavenged from work's trash, old Thinnet cabling being tossed). So, the antenna, and two BNC Ethernet terminators (dummy loads?) in parallel, and wouldn't you know it, I can now receive that repeater with almost zero static.

So I'm confused by this. ADDING load to the line IMPROVES reception?

The whole story is a lot more drawn out, and it's odd how I actually came to discover this phenomenon that seemingly improves reception (originally I had about eight of these tees all daisy-chained off of one another, just screwing around), but when I asked my father about it, he suggests that the antenna has such a high gain that it overpowers -- and desensitizes -- the receiver in my radio.

I trust my father, but does this sound feasible? Why would I then not just be able to aim my antenna slightly off target and pick up the repeater equally well (or better)?

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  • $\begingroup$ Desense from a nearby strong transmitter? Do you live in a built-up area? Try removing the antenna entirely, or using the rubber duck but placing it on the floor, and scanning up and down 20 MHz for really strong signals. $\endgroup$
    – tomnexus
    Mar 18, 2019 at 6:41
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    $\begingroup$ What happens when you combine the rubber duck (instead of the Yagi) with the Tee and terminator? $\endgroup$
    – Brian K1LI
    Mar 18, 2019 at 12:46
  • $\begingroup$ @tomnexus I don't have scan, unfortunately, but setting the frequency up and down by 5 MHz steps, to 20MHz high and low, I pick up nothing but static. I do live in a city, my area being more like a suburbia rather than, say, an urban core. $\endgroup$
    – CJ KE4EDD
    Mar 18, 2019 at 23:14
  • $\begingroup$ @Brian K1LI I get a very weak signal from the repeater with just the duck and terminator tees. $\endgroup$
    – CJ KE4EDD
    Mar 18, 2019 at 23:15
  • $\begingroup$ For what it's worth, I tried something else, inspired by these suggestions. Replacing one of the two terminators with my duck, I get a signal weaker than with terminators, but when I wrap my hand around the duck, signal dies entirely, much like having only the yagi connected. So this implies the duck is receiving at least some of the signal in that configuration. $\endgroup$
    – CJ KE4EDD
    Mar 18, 2019 at 23:29

1 Answer 1

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A four element yagi shouldn't overload your receiver unless you're very close to the transmitter. If you were close enough for that to be an issue, your rubber duck antenna would work just fine.

When you added the tee to the cable, you created a quarter wave stub trap that would filter out certain frequencies. It would probably work even better if you shorted the ends instead of using resistors.

Those tee connectors aren't that big, so I'm betting your problem is from interference that's somewhere around the microwave part of the spectrum.

Maybe a different radio with better built-in filters would work better. But, if you have a solution that already works, you may want to stick with it.

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  • $\begingroup$ I agree that if the problem were overload then the duck should be enough. I was wondering if the duck had just below a threshold to receive, and the yagi too high above. Stock ducks do have a reputation for being incredibly poor performers. I'll have to spend some time outside this weekend with my antennas a bit higher and compare. $\endgroup$
    – CJ KE4EDD
    Mar 18, 2019 at 23:49
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    $\begingroup$ YES, the shorted tees bring the signal high enough to break the squelch now. No other combo did that before. I like your answer, and I have some research to do. Thank you for the link, too, it's a solid start for me. 73, de KE4EDD $\endgroup$
    – CJ KE4EDD
    Mar 18, 2019 at 23:53
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    $\begingroup$ For my first couple of years as a ham, my only radio was a Baofeng UV-82. It works well enough for the most part, but it can't receive weak signals that many other radios receive with ease. If I come across some tee connectors, I'll try building a trap like this to see if it helps. Who knows? It might help other owners of budget-friendly radios. $\endgroup$
    – mrog
    Mar 19, 2019 at 15:37
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    $\begingroup$ I bought this phone specifically due to the 2-way plus the relatively current specs, ruggedness... it's a decent package, really, if you're fortunate to get a properly QA model. Ultimately, though, it's a toy for learning with and so far it's done a good job of helping me learn. I needed the cellphone for work, wanted an amateur transceiver, found both in one package for sub-$500. For me, a win-win until I have the spare funds for something better. $\endgroup$
    – CJ KE4EDD
    Mar 20, 2019 at 2:37
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    $\begingroup$ If it is a stub trap that's reducing some noise sources, you should play with varying the length of the stubs. Maybe start with some longer coax on the tee and short them closer and closer to the radio until you find some minima in the noise or maxima in S/N. $\endgroup$
    – hotpaw2
    Mar 21, 2019 at 5:18

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