[OZAPRS] Mobile whip for 30m

[Terry, VK5ATN]

The mobile whip I use for 30 metres is wound as a helical with the pitch 
of the windings increasing from bottom to top - much in the style of the 
original 27 MHz winding which I removed.

The number of turns was established by experimentation and using a dip 
oscillator to establish the correct number of turns for the desired 
band.   This is very hit and miss, but the original guess cam fairly 
close to where I wanted to be.   It would have been easier with an 
antenna analyser - something which I now have - having worked through 
some 35 years of antenna building without.

I actually discovered two of these whips by accident in the DSE store in 
Pultney Street Adelaide when they were divesting of serious radio 
interest and equipment.  They were on special (including the base) for 
around $29 each.  I didn't take long to grab them.  They are still on 
the Mobile One site for $185 ( It's nice to have a win sometimes).    I 
wound the second one for 20m again using the TLAR formula (That Looks 
about Right).     Each of then had an earlier part time life on my 
tractor mobile as well as on the ute at a somewhat higher speed.

I've also used a series of home brew mobile whips  using an aluminium 
mast and a close wound interchangeable  series of top loading coils 
based on the Scalar series now long gone.    This is a very flexible 
system which also works well.

Interesting stuff this antenna experimentation  :-)

References:

http://www.mobileone.com.au/antennas/2h_27mz%20helical.html

http://www.users.on.net/~tfneumann/Amateur/AR_Ex.html

73
Terry
VK5ATN



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