[TowerTalk] SteppIR Wind Damage

[BobK8IA at aol.com]

In a message dated 11/28/2006 8:02:22 P.M. US Mountain Standard Time,  
vr2bg at harts.org.hk writes:

If this  is an older SteppIR & therefore came with
the original tubes, something  to remember...

Apparently the dielectric constant of later tubes
is  different than previous ones.

Mixing old & new tubes is something I  am not sure
how to accommodate with the controller.  If only
change  one tube for a new one, guess it is best that
it is used on the driver, as  can easily find/fudge how
far to extend the strips.

Likewise a whole  element - better to put the new
tubes on the driver than a parasitic  element.

What to do if >1 element has new tubes & the
rest  are old, I dunno.

My dipole has broken the element housing
instead  of the tubes with winds not to different
than reported above.  Not  sure which I would
prefer to sacrifice.  ;^)

73,  VR2BrettGraham




Brett raises the needed concerns about mixing element  vintage. In my case 
here, my 3 element SteppIR (erected March  2003 by TowerTalk moderator K7LXC) 
survived a 71 mph wind in July 2003 but a  80+mph wind in August 2006 broke a 
driven element half. That necessitated  replacement of the "older style" element 
support tube with the newer  style.
 
The 3 el SteppIR here is mounted about 8 feet above a 3  element 40m yagi. 
That puts it out of reach for me to do the replacement, even  standing on the 
40m antenna boom. My good friend KC7V, who is quite a bit taller  than I am, was 
kind enough to do the repair. He could reach it ok, but put a  temporary step 
on the mast to make it easier. He replaced the half driven  element tube only.
 
This mix of element vintage did shift the low swr points up in  frequency 
slightly, but certainly not enough to get excited about. A simple  driven element 
length tweak brought things back into play nicely. 
 
I did not notice any performance problems during either mode of CQ  WW this 
season. F/B remains excellent as before and I was pleased, as usual,  with how 
it played in the contests, since I take that aspect of our hobby quite  
seriously.
 
I will eventually rebuild the entire antenna using the newer tubes.  They are 
stronger. That will probably happen sometime next year and be done with  a 
crane with man basket. It will be an easy one man job and I wont have to  
dismantle the 3 el 40 yagi to get to it. At that time, I will changeout the  
firmware to keep everything constant.  

73,
Bob K8IA
Arizona  USA