[Towertalk] SteppIR

[Rick Tavan]

The following are preliminary impressions only. I have some interaction 
problems that invalidate any quantitative results to date. Nonetheless, ...

I put up a 3el SteppIR last month. It went together beautifully. 
Materials and documentation are first class. The only assembly problem 
was a marginal supply of the self-fusing tape that you use to seal the 
fiberglass section overlaps. They sent me another spool and promised to 
increase the allowance in future manufacturing. I was in a hurry and 
didn't want to wait, so I scrimped the last few joints and one will 
probably have to be re-taped the next time I take it down, hopefully not 
for a long time. FluidMotion assured me that even an untaped joint is 
highly unlikely to come loose.

Having gain on 17 and 12 for the first time is wonderful. The 180degree 
reversal feature is amazing - 4 or even 5 S units difference on some 
paths. I enjoy using it to switch between JA and Caribbean although it 
takes a few precious seconds during which you should not transmit with 
high power; annoying in a contest. The bidirectional feature hasn't done 
anything for me yet and seems to have higher SWR than the unidirectional 
modes. But see below.

But none of the above is why I bought the antenna. I wanted a good basic 
tribander with low SWR across 10, 15 and 20. I got that on 20 for sure. 
I used it in the CQP this month and it felt at least as good as my C4S 
on 20. Of course, with twice the boom length, it certainly should! SWR 
is good across the entire band. On 15 and 10 I did not feel even 
relatively loud. (From this location, the little C4S actually does feel 
loud, but it was down and unavailable for direct comparison. Conditions 
during CQP were mediocre.) SWR was also on the high side - 1.4 to 1.8. I 
believe I have an interaction problem with an 80m rotatable dipole about 
two meters below the SteppIR. I can see this in SWR changes on the 
dipole when I adjust the SteppIR. I had ignored Force 12's good advice 
to mount that dipole at ninety degrees to other nearby elements. I 
intend to twist the dipole 90 degrees real soon now. Hopefully this will 
fix the problem. I have heard several complaints of similar interaction 
problems on the SteppIR reflector 
(http://groups.yahoo.com/group/SteppIR). I can't say whether the SteppIR 
is more or less susceptible to such interactions than other antennas. I 
can say that when it bothers another antenna in use, it's great to just 
move it to a different frequency and see that interaction go away!

A friend here in CA has a 2el SteppIR fixed on the US East Coast at 
modest height and loves it, especially the very short (<2m!) boom. I may 
have been running my SteppIR too high (about 24m and located on a 
ridge). In fact, at one time during CQP I lowered it to about 17 or 18m 
and maybe, just maybe, it worked better on the higher bands at that 
height. Too subjective to be meaningful.

I look forward to getting this antenna working to its potential and 
maybe putting a second one lower on the tower. This isn't easy on a 
crankup, especially with a 3el. The light weight of the antenna makes it 
feasible, though, so I'm tempted. Also, they are working on a 4el design.

Hope this helps.

73,

/Rick N6XI

George Shaw wrote:

>Anyone using the SteppIR in a 2 or three element configuration? Good or
>bad? Value for the bucks (pounds/euro)? How high off ground? Minimum
>height requirements, turning circle etc.
>
>
>
>George Shaw MI3GTO
>
>Mobile: +44 (0) 7740 361 163
>Email: george.shaw@ukf.net
>
>
>
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-- 

Richard M. Tavan

TIBCO Software Inc.
3307 Hillview Drive
Palo Alto, CA  94304-1213
650-846-5214
tavan@tibco.com

20297 Hickory Hill Way
Saratoga, CA 95070
408-867-5797
n6xi@arrl.net
rtavan@alum.mit.edu

408-896-0476 Cell
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