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



Hi John, 
 
Thanks for your detailed observations, which certainly agree with most of  
the PL-300WT (and G8) experimentation here.
 
It was a big surprise for me to discover the "bulletproof" nature of the  
new DSP radio, with its extreme resistance to overloading. I had been  
testing a new 9-foot (side) PVC-framed passive loop in my backyard, which  
previously had managed to overload any portable brought within 1 foot of its  large 
coil. The E100 (both Slider and stock) was especially bad, with multiple  
birdies and false peaks all over the place. (With analog radios, the monster  
loop simply "took over" all the tuning, forcing its resonant frequency into 
 the radio regardless of what frequency the radio dial showed).
 
The PL-300WT had no such problem, however. Both the stock and 7.5"  
loopstick PL-300WT's were extremely well-behaved when inductively coupled  to the 
monster loop, receiving a great signal boost on the loop's  resonant 
frequency, but only when the radio's tuned frequency was the same  as that of the 
loop. The radio showed no false peaks, even when the loop was  tuned to local 
sloppers. This fact alone was amazing, and put the radio in a  class by 
itself among the portables I've tested.
 
In the shootout between a 7.5" Slider E100, 7.5" Slider SWP (both with  
Murata CFJ455K5 filters) and a 7.5" fixed-coil loopstick PL-300WT, my results  
basically agreed with yours, John. The DSP-produced selectivity of the  
PL-300WT was easily a match for the Murata CFJ455K5 filters in the Slider units, 
 and had the added benefit of no muffled audio on the frequency of choice. 
In the  sensitivity comparisons, I found that the 7.5" loopstick PL-300WT 
had a slight  advantage over the fully-modified E100's and SWP's, primarily 
because of the  muffled audio from the Murata narrow filters on the frequency 
of choice. Tuning  these radios 1 kHz up or down improved intelligibility of 
the audio, but  slightly decreased signal strength, thereby giving the 
PL-300WT a slight  advantage (at least in my subjective opinion :>)  
 
The Slider-only units (E100 and SWP) were competitive in sensitivity with  
the 7.5" loopstick PL-300WT, however, with the Slider-only SWP showing a 
slight  edge over both the Slider-only E100 and the 7.5" loopstick PL-300WT on 
all  AM frequencies. Unfortunately, a Slider-only SWP is a non-starter for 
TP DXing,  with barn-door selectivity.
 
Like you, John, I will be taking quite of collection of stock and  
hot-rodded Ultralights to Grayland, eager to see how they perform in actual  
TP-DXing. The PL-300WT shows a lot of promise, but until it performs a few  
"miracle receptions" like we have come to expect from the fully modified E100's,  I 
guess we will never be fully convinced, right?  :>)
 
73, Gary       
 
 
In a message dated 6/27/2009 8:24:45 P.M. Pacific Daylight Time,  
bjohnorcas@xxxxxxxxxxxxxx writes:

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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