[IRCA] PL-300WT Tests On Going - Part Two
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[IRCA] PL-300WT Tests On Going - Part Two



Just kind of an interim Part Two for tonight.

I took the FM antennas off and the stock ferrite loops out of all three units and put them to work as 8" Sliders. Set up that way, one receiver seemed to produce just a bit better S/N ratio on the weakest signals, so it was converted back to a Barefoot Class PL-300WT. I was able to spend a couple of hours comparing one of the PL-300WTs and a stock IF E100 with both set-up as 8" Sliders. I moved down our mountain, at least 150 feet from any man made structure and (most importantly) out of and away from my metal-clad house. The first outdoor tests were very interesting.

The first thing that I discovered was that I had forgotten how nearly useless an E100 Slider is here on Orcas Island. The multi-powerhouses serving Vancouver and Victoria are all within 20 line-of-sight seawater miles of me here and an E100 Slider just overloads like crazy. More than 50% of the dial is unusable from splatter, birdies, images, slop and I don't know what all else.... its just awful. The PL-300WT was a real revelation, though. Reception was possible on every 10 kHz. channel. Adjacent channel rejection was just excellent. The only channels with any slop/splatter at all were just a few frequencies where I was next to the most powerful of the Vancouver stations.... There, I noted some splatter, but the station assigned to that adjacent frequency was very listenable/ ID-able to a DXer. The near bullet-proof nature of the PL-300WT will be a real boon to urban DXers, allowing the use of larger antennas, just as Gary has reported.

With all this wonderfulness surrounding the 300WT, I was surprised to find that - in raw weak signal sensitivity - my E100s out-performed the DSP circuitry of the PL-300WT on the lower half of the band. There were only a handful of frequencies in the 700-900 range that had weak signals that could be heard amongst the overload crud on the E100... The most memorable was KXL-750, Portland (I was testing 6 hours before sundown.) This far North, KXL is really quite weak in the day time. Time after time, the two E100 Sliders heard KXL better than did the either of the two PL-300WTs. The same things was true with a couple of stations in the 800s. However, above 1000 kHz., the PL-300WT was the equal and usually the superior to either E100 (these were all with stock filters.) I rush to say that all of the differences were quite small... and usually involved S/N ratio.

It will be very interesting to see how these babies compare out on the Coast.

I also noted the "AGC pumping" that Pete Taylor and a few others have mentioned. I listened to a lot of weak signals today, and I only heard the "pumping" three or four times. It seems to take the perfect signal level to trigger it. At the weakest discernable audio, things are very linear and normal. However on a signal that is about language recognition level, there is a definite rather large up/down movement in the volume with slight fades in strength. I don't think that this is the AGC. If it were the AGC cutting in/out, the volume would decrease from the existing setting as the AGC began to control a signal. If my ears were working, in this instance, the volume actually INCREASED abruptly and then dropped back down.... Like a pre-amp was cutting in for just a bit and then dropping back out. In any case, its most likely in the gain algorithm (the software definition of gain response) and something that we'll likely learn to live with. Just slightly stronger signals or really weak signals don't seem to exhibit this behavior.

I'm certainly in Ratzlaff's camp.... this radio seems to have a few quirks, but it is such an outstanding performer overall that I'll probably abandon my beloved E100s for domestic DX and almost certainly for TP/TA work, too.

I'm learning more about the S/N and overall Signal strength readings, too. They appear to be instantaneous readings.... a brief snapshot taken every two or three seconds. There appears to be no averaging or smoothing in these raw numbers.... I'd much rather see some small amount of averaging to calm the readings a bit, but I do still think that they will be a real help when comparing antenna systems. Also, it appears to me that "25" is the best signal-to-noise reading that the system can award... I haven't yet noted the maximum raw strength reading. I suspect this numerical read-out is worthy of study and discussion.

I'd love to know if my observations match or disagree with those of others...

Tomorrow. I'm going to marry up the PL-300WTs to a 1" x 32" Ferrite bar and to a 3/8" x 48" bar and try to do some comparisons...

What fun!!!

John Bryant
Orcas Island, WA
Winradio G313e and various Ultralights
Wellbrook Phased Array + Superloops _______________________________________________
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