A endfed vertical for 40m is around 67'. Could a coil be placed in the
center of the endfed wire to shorten it to say 40'? This would make it
easier for my portable QRP work but will it work? Any thoughts on a short
ended 1/2 vertical?

73

A endfed vertical for 40m is around 67'

No it is not. A 1/4 wave vertical for 40M is around 33'. If mounted at
ground level it requires an extensive ground radial system to get good results.
If you are talking a 1/2 wave vertical better to feed it in the center.
An inverted "L" with 33' vertical and 33' horizontal is around 67'. Still
requires a good ground.

Could a coil be placed in the
center of the endfed wire to shorten it to say 40'

Yes, but you need to remember the radial requirements, and if you start
sticking coils in the antenna, then the matching starts being a problem.
This would make it
easier for my portable QRP
For QRP and portable operation 40m-10m, a 50'-100' inverted vee fed with
300-450 ohm balanced line and a tuner. Get the apex up as high as possible.
You can not beat this for multi-band portable operation.
73 Gary N4AST

Need Help Please wrote:
A endfed vertical for 40m is around 67'. Could a coil be placed in the
center of the endfed wire to shorten it to say 40'? This would make it
easier for my portable QRP work but will it work? Any thoughts on a short
ended 1/2 vertical?

73


You might want to check out the article in the May 2004 issue of QST on
ppg 28. It is for a shortened end fed 1/2 wave 80 meter antenna.

Mike

Down-load in a few seconds and run immediately program MIDLOAD for a
complete design including number of turns on the coil. Can be made easy to
feed with a link coupling. Unfortunately, one band only.
----
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........



"Need Help Please" wrote in message
le.rogers.com...
A endfed vertical for 40m is around 67'. Could a coil be placed in the
center of the endfed wire to shorten it to say 40'? This would make it
easier for my portable QRP work but will it work? Any thoughts on a short
ended 1/2 vertical?

73

Need Help Please wrote:
A endfed vertical for 40m is around 67'. Could a coil be placed in the
center of the endfed wire to shorten it to say 40'? This would make it
easier for my portable QRP work but will it work? Any thoughts on a short
ended 1/2 vertical?

It will certainly work and if you put the coil in the exact center of
the 1/2WL, it will satisfy the folks who claim that the net current into
the coil is the same magnitude as the net current out of the coil. :-)
--
73, Cecil http://www.qsl.net/w5dxp



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(JGBOYLES) wrote in message ...
Hi,
If you are talking a 1/2 wave vertical better to feed it in the center.
Why ? A 1/2 wave antenna exhibits very high impedance on its end, but
it can be matched to any feeder by a 1/4 wave shorted stub of twinlead
or coax. This stub may be placed horizontally near ground and the coax
one may be even coiled. The antenna would be a sort of shortwave
J-pole. Its big advantage against a 1/4 wave groundplane is the J-pole
has only modest requirements on RF grounding. Lightning and static
protection are still essential, of course, but it is easy - the
shorted end of the matching stub can be grounded directly.

Could a coil be placed in the
center of the endfed wire to shorten it to say 40'
Yes, but you need to remember the radial requirements, and if you start
sticking coils in the antenna, then the matching starts being a problem.
If you cut the coil into halves, you will see a low (about 5 ohms)
balanced impedance there. The better idea seems to be: two identical
whips as long as possible and a matching coil between them. Another
coil (maybe 1 - 2 turns only) wound around the matching coil is
connected to the feeder. Download MIDLOAD.EXE from Reg's superb
collection http://www.btinternet.com/~g4fgq.regp/page3.html#S301" and
play with it a bit. If the total electrical length is 1/2 wave, the
radial requirements should be modest. Remember the bottom end of the
antenna will be near ground - possibly within reach of uninformed
people - and under high RF voltage !

73 Ivan OK1SIP