----- Original Message -----
From: "Gene Fuller" <w2lu@rochester.rr.com>
To: <caraj@cox.net>
Sent: Sunday, January 15, 2012 10:14 PM
Subject: Re: [TowerTalk] Dipole fed with balanced line?
> Hi John -
>
> It's not a question that has a "cookbook" answer. The old timers used to
> say "the more wire and the higher, the better". That might be modified to
> say "get as much current as possible as high as possible". On 80 even if
> you can only get he center 60 feet or so up high, with an additional 30
> feet dropping down at almost any angle from each end, for loading, it
> would probably work pretty good. The drooping ends would also help fill in
> the pattern notches on the higher bands. Just try to figure out where the
> most current will be and get it as high as possible.
>
> For getting it into the house, if there is a window pane anywhere near
> replace it with Plexiglas ( to still let some light in) and use feedthru
> insulators for the open wire, barrel feedthrus for the coax and holes
> (with goop) for the control cables. If the tuner won't tune the open wire,
> try longer or shorter open wire (by up to about 1/8th wave), but be sure
> to check all bands after you make a change because what may bail you out
> on one band may put you in the hole on another, so be ready to compromise.
> And with the tuner, if you find that there are different L/C ratios that
> will give you acceptable SWR, favor less coil and more capacitor since
> variable capacitors are generally more efficient than coils.
>
> Good luck with it. Look through any antenna books you can get your hands
> on and don't be afraid to experiment.
>
> 73's, Gene / W2LU
>
> ----- Original Message -----
> From: <caraj@cox.net>
> To: "Jim Miller Waco Texas WB5OXQ" <wb5oxq_1@grandecom.net>
> Cc: <towertalk@contesting.com>
> Sent: Sunday, January 15, 2012 8:58 PM
> Subject: Re: [TowerTalk] Dipole fed with balanced line?
>
>
>>
>> John:
>> I have a set up similar to your dimensions with the middle half of the
>> ant passing over the roof.
>> I use Radio Works classic North Carolinia 80 M - 10M Windom Ant about
>> 133' long, 67% offset. There are 2 baluns in it which can help the RFI
>> problem (If caused by the antenna).
>> The shack is 12 feet directly below the stub feed point, 30 feet below
>> the top balun feed of the 133 length. The ant top is 50' above ground.
>> With 600 watts PEP there is no RFI in a shack full of transceivers, lots
>> of quality test equipment
>> and many antennas. The house has 4 laptops, 2 high speed servers fancy hi
>> fi and wireless TV/Web. No RFI from this antenna.
>> It routinely gets 59+ in N., S. America and Europe. The first time I
>> joined a national net I was requested to do a call for NCS to find more
>> stations. For the far east on 20M I go to the beam. The home is at the
>> lower part of hills where the brook flows.
>> On your property I would turn the short leg of the above 7 feet down at
>> your tree or compromise to the keep the center as high as possible. My
>> ant is turned down 10 feet at each end but the feed point is sitting
>> pretty at 50 feet. The ant is fed through a tuner which is switched out
>> since the SWR varies from roughly 1.1 to 2.5 on band extremes.
>> Talk to me directly if you 4Mhz. is critical to you.
>> Good luck,
>> John, K2SFS, caraj@cox.net
>> _____________________________________________________
>>
>> ---- Jim Miller Waco Texas WB5OXQ <wb5oxq_1@grandecom.net> wrote:
>>> I must move my 40 and 75 dipoles due to rfi in the house that I cannot
>>> resolve. I am thinking about 1 dipole fed with ladder line or window
>>> line. I have 2 possable support points.
>>> 1 pair is 126' from end to end and 50' high at one end and 30' at the
>>> other. Second pair 139' apart but 25' at one end and 30' at the other.
>>> The longer but lower is farther from the house by about 10' and runs
>>> over level yard with no obstructions. What is up with the 130' dipole
>>> fed with balanced line? Is this better for a multiband antenna than
>>> using 1/2 wave at the lowest desired freq? I have a MT-3000A Dentron
>>> tuner which is supposed to work with ballanced line. The maximum power I
>>> run is 800 watts rms not pep.
>>> Suggestions please. I have never used a dipole fed with balanced line.
>>> Will the window line take 800 watts or should I get the open wire
>>> feeder? I really only need this antenna to work on 75 and 40. I use my
>>> triband beam for 20+. How do you bring this line into the shack?
>>> Obviously it cannot touch anything metal along its run. Is the length of
>>> the feeder critical?
>>> Should the wire be long as possable or 1/2 wave at the lowest desired
>>> frequency? (3.9mhz)
>>> wb5oxq
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>> c
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk@contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|