From: Jeff M. Gold (JMG@tntech.edu)
being senile, don't remember whether I posted this.. so lets
do it again ( I am currently teaching an intro to computers
course.. they are all doing a spreadsheet project.. taught
them so well..only need to be in the room to answer an
Well CQ a while back had an article about a 1/4 vertical
made very inexpensively from PVC. I made one and it worked
good and so I made a 1/2 wave to see what the difference
would be.. worked a lot better.. very broad banded and
surprisingly with only 2 radials..really gets the signal out
(see Feb 93 QST). These are helically wound.
Well been testing both the new MFJ 20 and 40 out and wanted
to take them both portable (they both will easily fit in the
bottom of my backpack).
I have the bottom section of my original 20 meter with 2- 40
meter length radials. I then wound the rest of the needed
length to make the equivelent of a 40 meter 1/2 half wave
(about 3/4 of the total needed coiling on the top section..
so I wouldn't have to mess up the 20 meter part). First try
no reasonable SWR..pigtailed another length of wire.. got a
little closer..put one more lenght then cut off a section..
never even soldered them.. didn't space out the windings..
and just used electrical tape to kinda keep things in place
while I was playing around. Using the MFJ digital antenna
analyzer makes these things easy for me to experiment with.
Well I noticed the only difference the coiling seemed to
make was to effect the electrical length of the antenna..
thus changing the SWR. Got the SWR down to about 1.3:1..
put a whole mess of tape around the mess I had created and
it was just starting to get dark.
I ran in the house and got the 2- MFJ rigs and a Gell Cell.
The antenna really seemed to be receiving well from my
driveway.. Heard someone calling CQ.. gave him a call and he
came right back. Think he was a 579 with 100 watts on a
Kenwood 450 and some kinda permanent antenna. Think that
wasn't bad for 4 watts and some plastic pipe.
I took the 20 meter top and replaced it and checked the
SWR.. was still perfect.. So I can use the antenna on 2
bands with the same 40 meter radials and just replace the
I am next going to see if I can use my small tuner to tune
it on someother bands...
I am going to come up with a very small light weight
multiband portable antenna that will go well with
backpacking (day packing that is.. I like to climb mountains
in the smokies and set up.. may start using my HW9).
Search QRP-L Archives
QRP-L Archive |
[ 1993 | 1994 | 1995 | 1996 | 1997 | 1998 | 1999 | 2000 ]
This archive was generated by hypermail 2b29 on Fri Jun 02 2000 - 11:26:08 EDT