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Author Topic: Are there comparisons of portable QRP antennas?  (Read 7005 times)
KA0HVE
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Posts: 117




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« Reply #15 on: August 12, 2013, 08:56:20 AM »

I can't remember exactly how it was worded but someone said something like, "Put up as long a piece of wire as high as you can, split it in the middle, and fed with balanced feedline using a tuner."  That's not always practical with portable operation but that's where the W3EDP comes in handy.  It has been around for over 70 years and is popular with the QRP operators across the pond from what I hear.

I have no usable trees at this point.  Need to find something to use as a tower/mast.
« Last Edit: August 12, 2013, 09:00:16 AM by KA0HVE » Logged
GILGSN
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« Reply #16 on: August 12, 2013, 11:03:49 PM »

The best I have found is a half-wave end-fed. Best wire: Wireman #534, 26 AWG, 19 strand 40% copper-clad steel. Actually I use a betterqrp.com tuner with a LNR Precision (PAR) 40/20/10 trail wire and choke, which uses the WM #534 wire, or equivalent. Shooting the wire up a tree with a slingshot, fishing weight and line is very easy. With a little practice, you almost always get it on the first try. The same tuner can be used for 30m with a separate wire, and maybe 15/17m with the 40/20/10 wire/choke, but I haven't tried. Contrary to what I have heard, in my experience, the length of the coax which acts as a counterpoise hasn't shown any noticeable difference in SWR or performance. I mostly use a 25' RG-174 cable; sometimes 15', 40', even up to 50'.

The wire/choke assemby is great because you get two or three bands with one wire.

The Buddistick works well by the way, up to 30m. I would not try it on SSB for QRP, though it might work on higher frequencies, but I've had good results with CW, even with as low as 2W on 30m. I don't use it on 40m, too short for any good results... That said I really like it because it doesn't require a tree and can be set-up in record time.

The regular PAR 40/20/10 works really well by the way, as would the trail version with their respective transformer boxes, but without the option of tuning. They do cover the whole CW portions of each band by the way. I have not tried them with SSB. Note that it works on 6m and 15m with a tuner; no idea about performance. I have not tried it on other bands.

Don't discard magnetic loops. If you use low capacitances (100pf max), you'll get very good efficiency. A 9ft. loop for 20m for example should work really well. I have a 21ft. perimeter loop for 30/40m that gets me easily to Russia from Florida on 40m using 5W (CW); the loop is inside my house! If you use thick coax for the loop, you can make it very portable. A mag loop also radiates at all angles in the loop plane.

The W3EDP I heard is great, but I can tell you from experience that shooting up a wire any higher than 50ft. is pretty hard. I have one but haven't tried it yet, because of space/height issues. Do most people use it sloped?

I do not use dipoles in the field because they require two attachment points, and the end-fed works great anyway.

"Random" wires work almost as well as end-feds, but require finding the right combinations of wire/counterpoise. Fortunately, these numbers are well known. I have too often felt needles in my fingers (RF burn) on my metal key trying different lengths. so I stick to the usual numbers.

Bottom line is, size matters... Not using a tuner is better... Of the five I mentioned, I would choose the end-fed first, hands down. "Random" wire second, Dipole third, Magnetic loop fourth, Buddistick fifth. But again, they all work.

Gil.
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KA0HVE
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« Reply #17 on: August 31, 2013, 08:53:14 AM »

The W3EDP I heard is great, but I can tell you from experience that shooting up a wire any higher than 50ft. is pretty hard. I have one but haven't tried it yet, because of space/height issues. Do most people use it sloped?

I have mine configured as an inverted L.  I think most people do it that way.  Yeah, 84' is a bit high for a vertical wire.  Grin
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NEVBEN
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« Reply #18 on: August 31, 2013, 04:47:05 PM »

I think there's two kinds of portable HF antennas.  There's the commercial products like the Buddi-pole and the Crank-IR, and then there's wire and the other bits you use to make your own.

If you operate portable out of a vehicle and can carry tripods and masts, and you're willing to spend more to have a well-finished product done for you, then the Buddi or Crank look like a good fit.

If you backpack, then you're not likely to want to carry more than some wire and maybe a balun.  But everyone has their own system based on what they're willing to lug around and what suits their purpose.

On the other hand, if you do vehicle-portable operations, but aren't interested in fairly expensive ready-made products, there's quite a bit more to experiment with.  There's the magloops, or with a single mast and some wire, you can easily fashion a vertical.  Mount the mast on a tripod or to your vehicle, with guys if necessary, and roll out some radials on the ground.  With two masts, you can hang a dipole.  You can get pre-made tripods like Penninger or Bluesky, and fiberglass masts like those from MGS.  With those kind of components, you can easily setup an antenna that outperforms a Buddipole, but it will almost certainly cost substantially more and will fill up the truck with equipment.

Plenty of people operate mobile with just a screwdriver or a hamstick, but going portable give you many more options.  Because what 'portable' means varies from backpack to truck, a shootout wouldn't be very fair.  Instead you have to consider how much you're willing to transport, and how elaborate it will be based on what you're willing to setup.  To me, a tree-hung dipole is too elaborate.  I don't have time to find trees much less mess around in the trees.  But a system with three masts, guyed-out for a center fed dipole at 35' is also too elaborate.  For myself, I'd consider the buddipole or the crank-IR -- that's about all I'm willing to setup -- except that I'm more inclined to experiment with stuff I make myself.  A single-mast vertical or a sloper from one mast to the vehicle might work fine.  Compared to the Crank-IR for example, I'll won't be able to change bands as conveniently, but to each his own.
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