RF PRO-1A XYZ 2010/10/28(Thu) 22:17 No.148 Shielded Active Broadband Magnetic “Moebius Loop” Antenna
約＄400.
WebサイトURL：http://www.pixelsatradio.com/
PDFファイル：http://www.pixelsatradio.com/PDF/RF_PRO-1A_Cut_sheet.pdf
参考記事（DXLD-yg より）以下：
Pixel Technologies PRO-1A Moebius HF loop
This is a very relevant news item. Pixel Technologies, which is nominally a
company that caters to the satellite radio industry, announced a few weeks back
that they were going to carry a new HF active loop that, from all appearances,
would challenge the well known Wellbrooks. Well, they've started to produce
them, and here's the PDF sheet with the details.
http://www.pixelsatradio.com/PDF/RF_PRO-1A_Cut_sheet.pdf
A review has been posted in the Eton E1 Yahoo group; as soon as I get the OK, I
will be copying it to the RadioReference wiki where everyone can view it. All
indications are that it's a very hot performer. Sadly it's too big to comply
with international postal regulations, so no shipping to Canada or overseas...or
so I've been told reading the traffic on this antenna in the RadioReference
forums.
It doesn't come cheap, but then quality rarely does. 73 (Mike Agner, KA3JZZ, Oct
26, NASWA yg via DXLD)
Review of the Pixel Technologies Pro-1A Moebius Loop for SWL
This is a rather long-winded two-page review of the Pixel Pro-1A loop. If you
just want the short version, then as long as you have 110VAC 60 cycle handy,
it's a great buy, and I'd encourage anyone to order it up. It works just as well
as an indoor unit (although it will work better outdoors, when it`s away from
the noise and any metal). For those of you who want more, read on.
First impressions, Unpacking, and Assembly
First impressions count a lot, and it's nice to see a company that puts up all
the necessary specs (including the Antenna sensitivity pattern) on the web, for
easy downloads. Second, the inside sales guys and the job they do are also
important, and Brian Graves of Pixel in Colorado did a good job of keeping it
short and sweet, and living up to their shipping promises. Hats off. Their
website is http://www.pixelsatradio.com/
The Pro-1A came shipped in a box that is 40x40x3 inches, and UPS delivered the
sucker without flaw or blemish. Now, that's quite a large box, and best make
sure it fits inside YOUR hatchback (it went into mine, with the back seats down,
but only just, and only at a bit of an angle). Unpacking the box, again first
impressions count, and everything is well-packed and has that look and feel that
says "professional grade". This is a case of your getting what you pay for ---
nothing looks half-baked, or like someone cut corners to keep the costs down.
Even the care taken with foam inserts and sub-component packing is first rate.
More appreciation from the customer at this end, guys.
The next step is to go through the paperwork --- yeah, yeah, I know --- nobody
reads the stuff, they just cobble together the likely bits and throw it up on a
temporary pole or the nearest convenient tree, right? Well, you COULD do that,
what with the stuff in the box which is more or less straightforward and fairly
obvious in its labeling, BUT… there IS a bit of electrical isolation involved,
so the order of mounting of the isolation washers, and the orientation of those
isolating washers may be important! (So Yeah, read the couple of pages that
comes with the product, for once, guys). If you are used to bolting together any
of the larger Ham or CB antennas (or even some of the bigger TV antennas for
that matter), then the rest of the assembly is duck soup. Pixel even includes
some very clear LARGE pics, for the reading-challenged among us. (And in this
case, a picture IS worth a thousand words).
Before you actually test it, you will need a few things. First, a suitable stub
pole (the thing that would eventually go into an antenna rotor, if you are going
that route, otherwise a piece of ABS plastic with no more than a 2" outer
diameter, and preferably about 5 feet long. You need this to keep the pre-amp
taut against the "L" bracket, so there is no ground loop. Second, for indoor
tests, you need a short piece of cable TV type coax with the F connectors on
both ends (don't worry about overloading the receiver because of a short coax
run, although Pixel do include some signal attenuators if this does prove to be
a problem). Specs and length on that coax test-cable between the loop and the
power-inserter-module doesn't matter much for indoor test purposes --- 6 to 10
feet long will do nicely. Last, you MAY want to have a short power-bar with an
on-off switch. The Pro-1A is fed with one of those wall-warts, and while it
doesn't get particularly warm, I like to turn the sucker off when the antenna
isn't being used. Last, the Pro-1A kit comes with an RCA-to-PL239 (screw-on
CB-type) connector, and if your set has other than that (like an Eton E1 or a
Sony with a 3.5mm antenna input), you may need a suitable input adaptor.
Fiddly Bits
This isn't one of those antennas that you just throw together, while hanging off
the top of the tower. While assembly is fairly straight-forward, still there are
a number of washers and such that have to be identified and then assembled in
the right order. And that means you want to do it where it's warm and dry and
well-lit. Take your time with the assembly and make sure the various parts are
in the right place, and none of the insulated washers are back-to-front, or
you're going to end up with parts touching at the wrong point, and that could
result in a short or a ground-loop.
That said, this is an easy antenna to put together, and all the tougher parts
come pre-assembled. There are various extra hardware bits, presumably for
alternate mounting or alternate feed-lines, and most of the stuff is common
North American thread, incase you lose a bolt or whatever. (Don't go losing the
insulated washers!) The kit even comes with a weather-proofing package for the
connector going into the pre-amp unit that runs down the mast, into the radio
shack (a nice touch).
Not Bash Proof
Like many loop antennas, the "loop" part is deceptive in its size. When the box
comes, it's light enough, and easy to haul off to your hatchback or van (a bit
bulky if you are trying to fit it into a compact car, especially if it doesn't
have a hatch). When you unpack the various bits, and lay them out on the ground,
the loop itself looks a bit small-ish (unless you compare it to something like a
Sony ANLP1 loop). When you get the sucker mounted on a piece of ABS plastic, so
you can test it out (and gloat over all the new signals that you can hear), then
the assembly seemingly starts to look bigger (OK, so it's just an optical
illusion). Part of this is the vertical bulk, part is because you are reminded
that the loop is somewhat fragile, going through doors or trying to set it up
where there is low headroom.
While the antenna assembly is nice and sturdy, it is intended to go 9 foot above
the roof-line and anything around it, and out of the way of anything that might
thump it. You are reminded of this, walking the test assembly around the house,
cause the loop is big, and its not meant to go jousting with doorframes and
furniture. Once it is finally placed outside, you are going to want to prevent
it getting hit with falling branches or similar. If you have trees in the area
that MIGHT shed branches in a storm, you may want to consider using a bit longer
insulated (ABS, fiberglass, or non-ferrous) pole, and attaching it to the
plastic vertical support rod that comes with the Pro-1A.
Getting the Test Loop Running
No fuss, no muss, bolt the thing together and tighten the various connectors,
and plug it into the receiver. I just used heavy-duty twine to brace the
over-sized lollypop loop-plus-ABS assembly between two chairs on the second
floor --- nothing fancy. That room doesn't have metal foil insulation, does have
big windows, and the loop is about 4 feet off the floor (maybe 20 feet off the
ground, outside). Tune the receiver to any medium-strength shortwave station
(preferable one you could "just" make out, with some strain, before) and WHAM!
The signal is there in Spades, like it was broadcasting from your home town.
Really. That said, there's a natural tendency when putting a new antenna on
line, to immediately dial in to some of those oddball obscure stations like
Mongolia or Solomon Islands (that you rarely, if ever hear), and expect to get
brilliant audio right away, regardless of the time of day. That ain't gonna
happen.
But this Pro-1A is a really worthwhile investment, in terms of increased signal
strength. I'd hazard a guess and say it gives a solid 6 dB (or more) gain over
the Sony ANLP1 that I've been using to date. And it DOES bring in a number of
new stations at respectable (identifiable) levels. It also uncovers a number of
new mouse-squeaks that will all have to be explored with a bit of patience to ID
them (but isn't that what SWL-ing is all about?).
If you are used to some other indoor amplified antenna, or a longwire, then you
are in for a treat, because a good loop antenna design is really really quiet.
Good signal-to-noise, but much more quiet than something like a 60 foot random
wire, or even an amplified whip. And the "nulling" capability means that you can
turn the loop to reduce the effect of your neighbor's satellite TV dish, that
hums like crazy in the rain, all over your reception. (The loop "null" is 90
degrees out of the hole of the donut, and your maximum signal is along the plane
of the loop --- seems a bit counter-intuitive for newcomers to amplified loop
designs).
As a frame of reference, the little Sony loop is a marvel, folding up to 9
inches or so, and bringing in respectable signals from around 4.000 through
21.000 MHz. It's not so great below 3.5 MHz, but that's asking a lot. And it`s a
bit of a pain, having to use the Sony's pre-selector for the band, but you get
used to it. But at $110 or so (shipping extra) it is a good buy. But it is
completely outclassed by the Pixel Pro-1A. No pre-selector needed from 100 kHz
all the way up to 30 MHz, and whopping signals with very low noise. Now, the
laws of Physics and radio wave propagation say that Outdoors, High-up, and
Really Big will almost always beat Indoors, Relatively Low, and Kinda Compact,
and the Pro-1A is no exception.
But if you DON'T own an antenna farm with several Beverage antennas and a
monster quad, then this might well be the best $400 you've put out on a compact
shortwave antenna. Highly recommended. Especially for small lots, apartments, or
ornamentally territorial wives.
Umn, excuse me … gotta go to the local Ham fleamarket and look for a rotor. And
the back of the detached garage is calling to me --- I think it needs some sort
of a Christmas ornament (like a big `O').
(Bob Stewart, Hamilton Ont., ODXA yg via DXLD)
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