SWR Tells Me??
 

"jimbo" wrote in message
...
OK, I have a new 2 meter j-pole antenna installed in my 3rd floor attic. I
have 50 feet of LMR240 coax running to the basement. I measure SWR at the
following frequencies on simplex.

144.2 2.5
145.2 2.4
146.2 2.3
147.2 1.9
147.9 1.7

Can I conclude that the antenna is electrically short for the 2 meter
band?

Thanks for any insight, jimbo

My experience has been that J poles can be fairly fiddely things to really
get right.
By right I mean SWR nearly 1:1 right in the middle of the band. However if
you are not so concerned with 'rightness' they can be a quick cheap way to
get on the air and I have nothing against that. I doubt if putting the
antenna up in the attic help much more than having it in the room near your
position. I have one I travel with made up like a pole lamp(remember these
from the 50s,60s).

Could be too short, Phasing section may be too long. Maybe both. Feedpoint
is probably in the wrong place. Balun couldnt hurt. Add about 10 inches of
coax to the feedline and check SWR again if it changes significantly you
need the balun. Not something fun to play with in the attic.