YC0LOW Writes:
>>
-----Original Message-----
From: Jo,YC0LOW <yc0low@gmail.com>
Last weekend, I finished installing the T-loaded vertical antena using
the
18m Spiderbeam fiberglass pole. It has 3 wire spokes for top load, each
at
15 meter long. Also, 3 elevated radials at 1/4 wavelength long in the
height
of 3 meters each. The elevated radials are still bended here and there
according to my limited land-lot area. The SWR 1,6:1 at 1825 kHz. The
lowest
1:1 is at 1800 kHz. I think I must pull out radials in
straight-and-level
form to obtain the SWR match and resonance (at 1825 kHz) and will see
if the
radial wires would need trimming.
I am using coax Andrew 7/8 inch about 21 meters in length as feeder
line. My
shack is in the first (not ground) floor. So, both (coax and radials
are
elevated). I am using home-made UNUN dual impedance (12.5 & 24 Ohms) a
la
W2FMI
This is my first time to build vertical antenna for TX on topband.
Would be
very grateful to hear any advises on what to do best to optimise the
antenna. TIA. Also, I'd like to express my gratitude to Bjorn, SM0MDG,
for
his suggestions and guidance in making this antenna.
I hope I can continue to present YC-land on topband. 73 de Jo, YC0LOW
W2PM Replies:
Jo - how much better a match are you lookiing for with 1.6:1?? ALso,
are you using a current balun choke at the feedpoint at the base? Very
important to avoid losses with the raised radials and coax coupling to
the earth unless they are high, over 15 ft.
73
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
_______________________________________________
Topband mailing list
Topband@contesting.com
http://lists.contesting.com/mailman/listinfo/topband
|