[Elecraft] Stealthy Antenna

[Dave]

Hi Mike

I've used a 100 foot doublet (dipole fed with open wire line) for several
years and it works reasonably well. I have a 4:1 voltage balun in a plastic
project box (the plastic version of a diecast box), it's mounted on the wall
right outside the shack with 3 to 4 foot of coax straight into the K2/KAT2.
I have sealed the box with silicon sealant and provided a small
drain/breather hole at the bottom. The feeder connects via a pair of brass
bolts/nuts with one on each side of the box. Not only does it look quite
neat, it's given no trouble at all.

I guess the open wire line is around 20 odd foot long. The "advantage" of
the 4:1 balun is in it's centre tap to earth that drains any static from the
antenna to an earth rod. The KAT2 tunes it to a reasonable match on most
bands, but the feed impedance can be quite fierce on some frequencies. If
there's a band you want and can't match, alter the antenna or feeder length
to get a better match.

You can model wire antennas quite easily with the free demo version of EzNec
at:

http://eznec.com

There is a good description of the doublet by one of the most respected
antenna modelling hams (L B Cebik, W4RNL) at:

http://www.cebik.com/aledz.html

Have fun

Dave, G4AON
K2 #1892

----- Original Message -----
From: "Mike Walkington" <walkingtons@attbi.com>
To: "Elecraft Reflector" <elecraft@mailman.qth.net>
Sent: Monday, January 20, 2003 3:50 AM
Subject: [Elecraft] Stealthy Antenna


> All,
>
> I'm planning to use a short piece of co-axial cable (6-7 feet) to get from
> my K2 (with KAT2) through the wall of the house to an externally mounted
4:1
> current balun (the W1CG model).  From the balun I plan to run twin feed
> (20-30 feet) to a doublet or loop mounted under the eaves of my two storey
> house (to avoid the anti-antenna covenants).  I have some questions about
my
> proposed configuration that I'd appreciate some advice on:
>
> 1) Can anyone offer some experienced advice on how long or short the co-ax
> can be?
> 2) Is it OK to mount the balun in a plastic box?
> 3) Would you recommend a doublet or a loop?
>
> Mike
> AC7MZ
> K2 #2599