matching 50 ohm line to 75 ohm antenna
OK, It's a monoband LP.
I am assuming that the inter-element crossover connections are correct.
Yes, double checked the assembly instructions
The feedpoint impedance is determined primarily by the dimensions and spacing of
the boom elements. They make a two element open wire transmission line. This is
fixed by the design and is not readily tunable [adjustable]. However, secondary
tuning adjustments are possible.
Its a plug and play, no tune LPA however i feel there are some strage
circumstances with the
feed or something as it worked fine at a different location & feedline
length.
The "shorted with a bar" is a tuning stub that provides some degree of
adjustment. As stated in another post you may have a 200 ohm or possibly 300 ohm
feedpoint impedance [VSWR 4:1]. Please tell us what VSWR value you are seeing.
A VSWR of 4:1 indicates a 200 ohms design; 6:1 indicates a 300 ohm design, etc.
No its a fixed bar and direct 50 connection.
Check the dimensions of the tuning stub for length as described by the
manufacturer.
No tunning
A LP is a balanced driven array. It should NOT be fed directly with coax [as you
describe]. Direct feed causes a current imbalance and currents on the outside
braid of the coax. You need either a choke balun or a ferrite based 6 meter balun.
No balun is needed however there maybe something strange going on so I
will try a coax
balun and try a fiberglass mounting pole, bottom line is i moved this
LPA about 30 foot, changed the polarity from vert to hor, same type of
feedline was used but instead of 70' its 35'long otherwize everythiong
stayed the same.
|