[Elecraft] VERTICALS

[Bruce Bowman]

I have a SteppIR vertical, the one they call the BiggIR which tunes 40m 
thru 6m. They work great in that they are always the correct length and 
with options can track the radio dial, automatically adjusting the 
physical length in small increments every 50 KHz. Unless you do 
something really dumb, the design is very durable with copper-berylium 
tape for the radiating element housed inside nested fiberglass tubes. 
The antenna requires guys at 8' above the base and you must use radials.

If you really would use it as a flag pole, I have my doubts. It's pretty 
'whippy' in a breeze with nothing attached. I suspect a flag could cause 
too much bending and snap an upper section in a stiff breeze. A Force 12 
would be a better choice for that sort of thing.

This antenna, and I'm confident any 1/4 wave vertical, is very sensitive 
to grounding. I've had to mount mine on the roof, and the vertical 
doesn't like being mounted up there (13' up in our case with the radials 
are layed out on our flat roof). I was warned by Fluid Motion (the mfr) 
this elevation would be an issue unless I could get it > 0.2 wave 
lengths off ground; that means more than 8m up to use the 40m band. At 
anything over 8m elevation, sloping the radials will improve the 
performance. It'a all in the report available on their site.

In my own case the real component of impedance dropped to very small 
values- I've seen < 2 ohms depending on the band. At 2 ohms, that means 
most of the power is being dissipated back in the 50 ohm finals of the 
K2 and not out at the antenna. Yes, the KAT2 matches the complex 
component of impedance, but it doesn't do anything about matching the 
real component of impedance... that takes a matching transformer. Simply 
getting a low SWR doesn't necessarily mean you're getting power out to 
the antenna.

If you can mount the antenna at ground level, then the real component of 
impedance should move up to 35-40 ohms and you should be a happy camper. 
Btw, the SteppIR will tune 40m - 6m as a vertical, and in a pinch will 
even tune 2m. For beams and the dipole from Fluid Motion, I believe you 
have to buy an accessory to tune 6m.

Also, there's a photo on their site of a pretty stealthy installation 
using their 20m-10m dipole (I don't know if it will tune 6m) mounted 
flat on a roof right at the ridge. You would have to know what you were 
looking for to spot it since it's only an inch or 2 off the surface. 
Check their site if that's of interest.

If you want to request info about any of the SteppIRs, don't bother with 
their e-Mail. They've given up because of spam and only respond to phone 
calls.

Bruce NM5B
Santa Fe, NM

----- Original Message ----- 
From: "John Wiener" <jawod at fuse.net>
To: "Elecraft email" <Elecraft at mailman.qth.net>
Sent: Wednesday, June 14, 2006 6:02 PM
Subject: [Elecraft] VERTICALS


>
> Maybe I missed it, but I didn't see anyone mention SteppIR, though I 
> seem to remember a mention of it earlier.
>
> I do not have one, but I've seen articles showing one masquerading as 
> a flag pole.
>
> As many know, the SteppIR has a metal "tape" element that is metered 
> out from the base within a PVC (I think) tube.  The antenna element 
> can be shortened/lengthened remotely to maximize performance on any 
> HF band.  This design intrigued me.  Seems many of us end up retiring 
> in CCR environments.  Who can argue with a good ol' American flagpole?
> http://www.steppir.com/
>
> (I have no connection with the company.)
>
> John
> AB8WH
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