Interesting post, ron,
Do you know what the loss is of the balanced line made from two CATV
coax's? We have plenty of 75 ohm hard line at N6IJ, and I am interested
in knowing if we stand to gain anything (so to speak by using the
technique you described...
73, DX, de Pat, AA6EG/N6IJ;
aa6eg@hh.tmx.com
599 DX Drive, Marina CA 93933
"The Contest Station from the Government"
On Wed, 3 Feb 1999, Ron Gang wrote:
> >To: Zdzislaw R Sawicki <ab2et@juno.com>
> >From: Ron Gang <gang@urim.org.il>
> >Subject: Re: [Antennas] 160 Meter Loop Feeding
> >
> >Hi Steve:
> >
> >If you have enough of that CATV hardline, let me suggest feeding the loop
> with TWO of these coaxes in parallel. Two coaxial cables of equal length
> and characteristics may be used as a balanced feeder. The shields of the
> cables are connected at both ends, with the inner conductors being the
> feedline, each one connected to a different side of the centre insulator of
> the antenna. At the antenna end the shields are connected to themselves,
> and at the shack end, the shields are grounded and the inner conductors go
> to the balanced terminals of your antenna tuner. Impedance of the line is
> twice the nominal impedance of the individual coaxes.
> >
> >Advantages over open wire feeders:
> >1. Not affected by rain, snow or ice in terms of impedance changes.
> >2. None of the pickup of QRN/M that open wire has, and possibly less stray
> radiation (my own experience when changing over from less than perfect open
> wire.)
> >3. Coaxes do not need to be spaced at a permanent distance, only need be
> the same length.
> >
> >If you want to use open wire from the loop in the air to the point you go
> underground, fabricate the open feeders to be the same impedance as your
> balanced coaxial feed to avoid any impedance bumps and undesirable impedance
> transformations. The Handbook gives a formula some place for what impedance
> open wire has depending on wire diameter and distance between wires.
> >
> >Hope that this may help you.
> >
> >73,
> >
> >Ron 4X1MK
> >
> >At 21:57 02/02/99 -0500, you wrote:
> >>After many years of "proving" that Ham Antennas do not instantly mean
> >>"electronic problems" I was Abel to get the surrounding neighbors to
> >>acquiesce to the installation of a full wave 160 Meter loop, it will be
> >>installed at about 45 feet (its the best one can get).
> >>
> >>The first problem is that the shack is located about 110 feet from the
> >>closest spot that the loop feed can come to ground level, to complicate
> >>the issue I have to bury the feed line ( so no 450 ohm line), no problem
> >>with this issue as a solution I got about 160 feet of prime CATV hardline
> >>(free) trenched it in over the warm periods this winter and made simple
> >>(plumbing) N terminating adapters, nice and tight and so far waterproof.
> >>
> >>I have started to assemble the loop using "quietflex" wire (nice stuff)
> >>the second problem that comes to the surface is in order to keep the
> >>visual impact down to the smallest profile I agreed to feed the loop
> >>with about 45 feet of (a) open wire line or (b) 450 ohm commercial
> >>ladder.
> >>
> >>The Question is, what is the best (ideal) "balum" and ratio to use to
> >>connect the hardline to the balanced feeder at this point it looks like I
> >>will use the 450 ohm line .
> >>
> >>Yes I will be using a "tuner" in the shack to get multiband usage from
> >>this antenna.
> >>
> >>Thanks and 73's
> >>
> >>Steve
> >>
> >> oo
> >> (__) AB2ET
> >>"I bet two extra terrestrials"
> >>
> >>___________________________________________________________________
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> >>
> >>------
> >>Submissions: antennas@qth.net
> >>
>
>
> ------
> Submissions: antennas@qth.net
>
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