[IRCA] 4' Air Core loop vs 5" FSL observations ...

[Stephen Airy <pianoplayer88key@xxxxxxxxx>]

I was listening to the comparisons that Gary DeBock posted in the ultralightdx group of the gain imparted to an ultralight radio with a 5" mini FSL vs. a 4-foot air core loop, and noticed a few things.


On 980 CJME, in the first part of the recording I can hear another station or two underneath them.  In the 2nd part, they're still there, but under a "new" type of hiss and harder to detect.  This hiss is the same type of thing I hear when my PL-380 and PL-606 are being desensed by strong local signals, but the weaker station is still strong enough to break through.  (I've had signals that sounded like this and indicated something like 49/25 or 50/25 - when I tuned off frequency to where no station was heard it was 49/00 or 50/00.)  The first part sounds relatively "clean" (although that hiss is still there, just not as prominent), though, but from what it sounds like and comparing to my similar reception situations, I wouldn't be surprised if the signal reading was actually lower.  (I've had cases where a signal was indicating maybe 50/02 or so near a strong signal, but when the local went off it cleaned up and was indicating more like 32/25 or
 so.  The recording of CJME doesn't quite sound clean enough for a 15/25 reading, though - I have seen those, for example on the 2nd harmonic of my local 1170 KCBQ (82/25 on the PL-606) with the whip antenna positioned just right.)  Or am I just imagining things with the recording?


That 1050 splatter really kills 1040 on the air-core loop, doesn't it!  I can still hear it, but it's much better on the FSL.  (One test I'd like to hear, if possible, is the 9-foot air-core loop tuned and directed at 1450-KSUH, and the FSL tuned to either 1440 (to try to get KODL) or 1460 (to attempt KARR or KUTI).)  I also hear that "desense-type sound" I mentioned above, but in this case the 2nd part of the recording is definitely superior.

1070-CFAX's recording is quite interesting to me.  In the 2nd part of the recording, I'm hearing what sounds a lot like one of the news announcers on KNX!  I can't positively ID it, though, although I'll mention that someone in Kalima, WA had KFI (another L.A. area 50kW ND station on 640) at 12:06pm today.  Gary, if you're reading this, any chance you could re-record 1070 at about the same time of day with whatever you think would be the best antenna to bring out that signal, and try to include either TOH, or the traffic at :05, :15, :25, :35, :45 or :55?      This recording - http://www.mediafire.com/?tod6q8ddtt22c9l - has the KNX traffic sounder in it (and is my typical midday reception on KNX (50kW, 111 mi) with the PL-606 coupled to the Select-A-Tenna and a chain-link fence, and http://www.mediafire.com/?qretc5q74onf5vz was KNX at TOH recorded a year and a half ago on the barefoot/stock PL-380 in my house (and may give you a hint that
 sometimes you might need to listen for the legal ID quickly spoken by the news anchor practically mid-newscast a little BEFORE the standard time it would normally air.)
Just wondering - what 50kW-or-less stations over 100 miles away do you have with comparable barefoot daytime reception quality?  Also how strong is CKWX-1130 there?  They are my first ULR Canadian I logged from here, helped by my local 10kW co-channel 6 miles away on the same heading being off the air for a while one night.  (I posted earlier about it, on the 1st or so.)


On 1520-KGDD's recording, I heard what sounded like a KXA (KKXA) ID at around 0:32 or so.  Also, I heard what sounded like skywave fading (in addition to the fade caused by two stations being off frequency) - is there any possibility sometime of doing tests when there's no skywave detectable (if i don't have to wait till around June 21 at local solar noon that'd be nice), or are the loops just THAT sensitive?

Speaking of FSLs, I've been noticing quite a few very small bars advertised on ebay by "costcocity003" and "sicilydreamer".  They're sold in packs of 6, and sizes include 1.7x12mm for $2.92, 4x10mm for $3.04, 5x10mm for $3.28, 3x15mm for $3.06, 6x16mm for $3.97, 4x20mm for $3.28, 10x25mm for $5.87 and 8x30mm for $5.63 (lowest prices given, not including shipping or tax, all shipped from Hong Kong).  I've been thinking about the possible idea of building my own SiLabs-DSP-based (not sure which chip(s) I'd use yet though - if I could have AM C-Quam capability that'd be nice for example) ultralight radio - target size would be something no larger than about 20-25mm thick, 50-75mm wide and about 75-100mm tall or so.  I'm just wondering which of 3 types of antennas might work best - single traditional 3" x 0.375" (cut to 2.5" if necessary or maybe a 4x0.25" cut to length) Amidon-61 bar wound with 660/46 Litz wire, a rectangular air-core loop wound around
 the perimeter of the radio (for example 70x90mm), or a rectangular FSL with a circumference of maybe 320mm and a diameter of say 20 mm?  Has anyone experimented with such tiny bars in pocketable FSLs, or would I still have a chance to be the first (I'd prefer to learn from other people's mistakes rather than my own) to experiment with it?

73,  Stephen
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