Antennas

[Gerald Wolczanski]

mo - I make my own open wire line with 4" spacing and have used that, in
conjunction with various length flat-tops, with great success.  With
shorter flat tops, I have made them with double wires with 12" spacing,
to lower the antenna Q which helps on the lower bands.

The 450 ohm window line can get lossy when wet/dirty.

It's easy to bring open wire into the house as the wire fits easily
under the windows.

I make my own spark gap lightning arresters from an ancient design I
found in an old ARRL handbook.

I've mostly used old style link coupled tuners.

Never found a condition where I could not tune the system to resonance.

For the low bands (or listening to aircraft beacons!), I can tie the two
feeders together and treat the antenna as a top-loaded vertical, worked
against ground.

                               - - - - -

Quite frankly, I've never fully understood all the gymnastics hams go
through to AVOID open wire systems - that includes the G5RV, various OCF
antennas, etc.  

Way back in the day when embassies used HF (imagine two 75 baud
channels!) our antenna of choice was the HFAS-1, a fan-dipole (66' and
100' versions) fed with 6" open wire line to a remotely tuned coupler on
the roof.  Nothing beat it.

I think it's important to use a truly balanced coupler such as the "old
fashioned" link-style.  I run QRP mostly (2 watts or so) - at higher
power levels, I worry about using toroids - I think I'd use an air core
BALUN.

I'm blessed with a lot of trees and most of my antennas stay up for a
year or two.  At the moment I'm using a 135' inverted-L fed with a home
brew Z-match - the toroid version of VK5BR's famous design.  When this
antenna falls down (it's long overdue), I'll probably go back to a
balanced antenna, for no particular reason.  The inverted-L flat-top
portion is 75' and works FB.

Photo of my Z-match, which is supposed to also work with balanced
antennas:
http://withywindle.us/wp/2014/06/17/jerrys-gear-and-new-z-match/


Jerry
KI4IO
Warrenton



On Wed, 2014-06-18 at 22:53 -0400, Mike O'Dell wrote:
> Consider the Offset-Fed Dipole such as the G5RV
> 
> the feeline is a length of 450 ohm window line
> that terminates in a choke or balun which 
> transitions to 50 ohm coax.
> 
> it's commonly held that the window line forms
> an important part of the radiator on certain bands.
> 
> If one had an antenna tuner with a balanced output
> (eg, an internal 4-1 current balun), would it make
> any sense to drive the window line directly from
> the tuner? 
> 
> what if the tuner were designed for remote use
> so the window line stayed well away from the shack
> and the tuner was fed with the 50 ohm feedline?
> 
> is this worth the trouble of doing beyond
> using something like a good G5RV with
> the tuner at in the shack at the radio
> end of the 50 ohm coax?
> 
> Note this is not a question about the G5RV per se.
> one can find copious advice about the strengths
> and weaknesses of the G5RV - some of it might
> even be correct. (grin)
> 
> AlphaDelta makes a multi-wire dipole with 
> multiple legs cut for different bands 
> without traps.
> 
> any comments as to the AD vs an OCF dipole
> (Windom, G5RV, etc) for a multiband wire antenna?
> (assume tuner adjacent to the rig driving 50 ohm coax)
> 
> 	-mo
> 
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