[Elecraft] OT - SteppIR Vertical and Elecraft Products

[David Wilburn]

Good stuff as always Ron, thanks.  The multiple wires on the 
fiberglass is a VERY interesting idea.

Plus if I add sections, 43'ish is 5/8 on 20m, the main ban I operate 
on.  I am mainly interested in 40' and up.  I'll get 80 and 160 with 
other wires.

Thanks for taking the time to reply Ron.  I seldom walk away from one 
of your enjoyable posts without learning something.

73

Dave Wilburn
NM4M

Ron D'Eau Claire wrote:
> If you are talking about multi-band operation, you can expect the SWR to
> range up to above 60:1 on some bands, particularly where the radiator is
> near 1/2 wavelength. That's why ATU's designed for operation at the antenna
> are used for such applications. And, yes, they tend to be expensive. 
> 
> The Stepper antenna adjusts its length to 1/4 wave on the band in use,
> AFAIK. That way it presents a decent match to coax on any band in its range.
> 
> However, matching to a longer antenna up to 5/8 wave provides substantial
> low-angle gain over a 1/4 wave radiator. That's easily done with a matching
> network at the base. 
> 
> One way to accomplish that at a lower price than a commercial ATU at the
> antenna is to put in a matching network for each band, relay switched, at
> the base. On some bands only an inductor will be needed, with taps for each
> band selected by relays if you are adverse to going out to the antenna. On
> others capacitors may be involved (such as when the antenna is near 1/2 wave
> long and presents a very high impedance at the base). IN that case you might
> have a separate network that is switched in. 
> 
> It's not as "hammer simple" as buying an ATU and plugging it in, but it can
> be even more efficient and at a lot lower cost. For many of us, that's what
> makes Ham radio fun: doing for $1 what anyone with a fat wallet can do for
> $100. 
> 
> You can probably get away with one matching network setup per band, at least
> on 40 and up, and keep as low an SWR to the actual rig as you want using the
> rig's built in ATU. (That's what it is really for ;-) Just be sure the SWR
> on the coax isn't so high you have unacceptable losses.
> 
> With an insulated pole like you have, another way to economically arrange a
> vertical covering several bands is to tape several radiators to it,
> insulated from each other, each 1/4 wave long for the band of interest. You
> can feed them in parallel with one run of coax, especially when dealing with
> harmonically-related bands (e.g. 40/20/10 meters) but it can be made to work
> on other combinations with a little pruning so that the SWR is low enough to
> avoid excessive coax losses. Then you let your rig's ATU do the final
> tweaking to keep your finals happy.  
> 
> You might do a little research on radials. The relationship of the number of
> radials to antenna efficiency is not linear. The more radials you have, the
> less adding more improves the efficiency. Also, the higher the feed point
> impedance, the less important near-field ground losses become. For example,
> a half wave radiator with a feed point impedance typically several thousand
> ohms is very efficient with no ground connection at all.  OTOH a 1/8 or 1/16
> wave radiator with a feedpoint impedance of less than an ohm requires the
> best possible ground for any reasonable efficiency. 
> 
> 
> Ron AC7AC
> 
> 
> -----Original Message-----
> Recent discussion regarding verticals, internal antenna tuners and 
> remote antenna tuners was very interesting.  Based on that discussion, 
> it seemed the "optimized" solution was a vertical, with good radials, 
> and a remote tuner at the base (generalization).  
> 
> In the near term I want to try out (experiment with) a 33' vertical. 
> At Frostfest this year I picked up 32' or so of fiberglass mast.  I am 
> going to tape a wire to this that is 34' long, twist the mast to wrap 
> the slack up, much like a widely spaced helical.
> 
> When setup at home, it would (eventually) have a good ground field 
> (would start out with 16 radials and work my way up to 60'ish). The 
> coax run when used at the house would be less than 40'.
> 
> When setup for portable operation (connected to mount I have for my 
> trailer hitch, to use when parked) it would have 4 radials of a length 
> not yet determined and the coax run would be less than 20'.
> 
> In both cases I would be using the tuner for the K2 (portable) or K3 
> (at home).
> 
> In the long term, I am thinking about the SteppIR vertical (haven't 
> decided which one).  Same deal with the radials.  It would inherit 
> what I had down, or start at 16 and work up.
> http://www.steppir.com/files/vertical%20brochure.pdf
> 
> Current plans are for ground mounting.  I understand that as radials 
> go, more is better. The radials would be black insulated wire on, or 
> within 1" of the surface of the ground. They would not be cut to 33' 
> or less if the space was not available.
> 
> I am curious on the experience of the group with a similar vertical, 
> tuner at the rig, and short coax run.
> 
> I am also curious of the experience of the group with the SteppIR 
> verticals.  There is similar up front cost as the vertical / remote 
> tuner solution (assuming a new weather proof tuner).
> 
> Thanks for the always enlightening discussions.  73
> 
> Dave Wilburn
> NM4M
> 
>