Re: BCT15X Sensitivity


Rick NK7I
 

Comparing a whip on a desk to an antenna in the attic is not necessarily a valid test.  I have Hardy board siding, which proves to be an excellent RF shield (it's made of concrete, in part).  It's also possible that the losses from the attic are not equal to the losses on the desk (through walls, next to noise sources).

Side by side, sharing the same whip antenna (a tee connector) would be a valid test.  Even moving one whip or being slightly different could place that antenna in a null; make them equal.

As mentioned prior, the arrangement of your system may give the 15x too much signal, overloading it (counterproductive).  A stray voltage may have leaked out from the attic amp causing damage too (if not DC blocked adequately).

The S meter, is useless nowadays, it's a relative meter UNLESS one has taken the time to calibrate it; it's doubtful that Icom did more than a gross calibration (to meet spec, ship it).  As you found, the 15X meter, has no value or usefulness.

After a fair comparison, it's entirely possible that you've lost an element in the 15x making it more deaf, but to be sure, as you are hearing a station, wiggle the antenna connector too and note any differences (one of the weaker points of any radio, easily abused).  Ditto any antenna connection on that feed (you've done part of that by switching ports) and validate the integrity of the cable (chewed on by tiny livestock?).

It may be time for it to be serviced; but when you send it in, try to document what you noted and tested (comparative tests, which band/s tested, types of signals used for the test [AM/NFM/P25], not "it doesn't hear').  You may have a weak or failed amp circuit (blown part or out of tolerance) or it may simply be grossly out of alignment for another reason.  It can happen on new radios or old.

GL es 73,
Rick NK7I


On 12/12/2021 8:43 AM, Leslie Polt wrote:
Interim Report: I tried different multicoupler ports and even the discone feeding 15X directly; as expected, the same results. A signal must be at least S7 on the ICOMs in order to break minimum squelch on the Uniden, and then it's received weakly until it is an S8 or 9 signal on the ICOMs. Interestingly, the 15X "S Meter" shows 5 bars on any signal strong enough to break squelch, so it doesn't seem to serve any purpose. The Uniden specs. indicate AM sensitivity  at .3 mV, whereas the ICOM specs are not better than 1.6 mV (the R7100), so I would expect more from the 15X.  On a lark, I compared the reception of the 15X with a handheld BC125AT/Diamond RH77 whip sitting on the desk, and they received about the same. I would expect far better reception with a desktop scanner and attic discone configuration. With both the Close Call and attenuation features disabled, is there any other setting on the 15X that could be degrading the signal? I have several Uniden handhelds (analog and digital) including the BCD436/536 twins and have been very pleased with them, so this is the first time I've experienced questionable performance in a Uniden.
Les Polt, Esq.
K3JTP

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