Haven't said a blessed thing about your radials, which will make or
break it. Someone talked about a problem with using a SteppIR on top
of a loaded tower. Been a while and don't recall the particulars,
probably should search the archives.
73, Guy.
On Sun, Apr 3, 2011 at 12:29 PM, Jerry Keller (K3BZ) <k3bz@verizon.net> wrote:
> I want to try a shunt feed on my 60' aluminum freestanding tower topped with
> a 4 element SteppIR. The tower is a Heights and it tilts over on a 4' high
> top-hinged base. I've come up with the following specs I dug out of K1ZM's
> book "DXing on the Edge":
>
> (1) Three #14 stranded insulated wires spaced 15" from tower leg and shorted
> top and bottom as an 8"-on-a-side triangular cage, running from top of tower
> down to where the tower joins the hinged base (4' above earth level because
> of the hinge). That would make the shunt 56' high.
>
> (2) I'd like to use an omega feed with air variable caps I liberated from an
> old tuner. I notice that most often vacuum variables are used for this
> rather than air variables. The plates in the air variables I have are spaced
> about 3/16".... will they handle a KW without arcing?
>
> (3) I want to put the feed caps in a plastic box at the 4' level so the
> shunt won't interfere with tilting the tower over. The tower grounds and
> the radial system would connect at ground level to a flexible copper line
> running from ground level up to the feed box. Would that work OK at 160M?
> If it's important, I could run the shunt the full 60' down to ground level,
> but it's mechanically more difficult.
>
> (4) With this arrangement, how important is the SteppIR? Would I need it for
> top-loading? The SteppIRs elements "float" above the grounded boom...
> should I plan to ground them to the boom?
>
> Advice, alternatives, comments? Any input appreciated.
>
> 73, Jerry K3BZ
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
|