This may be of interest to some here.
I too use CMC's at both ends of my OWL. Enclosure Box spacing set the
distance for a 488 ohm Zo on the lines. Chokes are rated for an easy KW
with RG 393 teflon center conductors as the internal wiring. External
wiring is 1/8th inch Phosphor Bronze wire rope. Approximate length is 45
feet overall. I just eat the impedance lump within the box.
FWIW, I experimented with chokes distributed linearly, every 12 ft or
so, and also lumped at the ends (tuner/choke-6 ft choke-- OWL to within
6 ft of feed point and then 2 chokes separated by 6 ft. then to feed
point). As I recall the linear separation was less noisy, however that
was an uncontrolled experiment. I would like to do that over again with
similar chokes in both feed lines but its a hassle to make and string
them up.
My local noise is now (AM Mode, 9 KHz filter, preamp 1 on on the 7800)
at roughly S3-4. The last of my interior noise sources was reduced (Fios
Battery Charger) just last week. I don't know which was louder....FIOS
Chargers and Direct TV HDDRV boxes. Both had my house wiring singing.
The FIOS Fix took 2 S Units out of the 14 Mhz band. These levels
achieved thanks in part to transmission line chokes and of course the
hard bits-finding and quieting my home.
The antenna is an aluminum dipole at 27 ft high and 50 feet in length. I
use it on 80-10M.
I also agree with those that suggest interior to our own homes is of
great concern. Everything you plug in radiates trash it would seem.
This solution works for me because of neighborhood restrictions.
Chokes Pix at:
http://w5pg.files.wordpress.com/2010/10/p1011590.jpg
http://w5pg.files.wordpress.com/2010/10/p1011602.jpg
http://w5pg.files.wordpress.com/2010/10/qro-choke.jpg
I am very happy with my receive and transmit environment now. Noise is
largely a non issue and zero TVI anywhere inside or out. CalQSO Party
ran 24X7 with 500W with no complaints. My neighborhood is a normal
suburban lot type here. I went to these extremes because I cannot
operate comfortably with any kind of TVI/RFI to myself or others. It may
not float your boat but it works well here in my circumstances. Best,
Chas W5PG
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