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Author Topic: Third Floor Condo Antenna  (Read 7324 times)
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aa5wg
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« on: October 23, 2013, 10:49:23 AM »

Hi to all,

My folks are moving to a third floor condo (top floor) when it is finished.  At present the condo only has the studs up.  Ma (a ham) would like to borrow my Drake TR7 station.

Outside antennas are not allowed.

What are your recommendations for an inside condo antenna and possible ground?

I was thinking about a closed or open center fed loop antenna going around the condo through the studs. The wire would be about 8.5 feet above the floor (9 foot ceilings).  We are considering feeding the antenna with ladder line or twin coax utilizing a link antenna coupler.

For grounding I was considering a continuous loop of wire through the studs about 6 inches off the floor.
Both ends of the loop would meet at a plastic junction box.  With a simple banana plug arrangement both ends of the loop could be shorted together or left open.  One end of the loop would go to a home brew series resonant circuit to help cancel any reactance.  This home brew series resonant circuit is like the MFJ-931 "Artificial Ground" product.

That's it.  Any ideas to help with this challenge?

Thank you.

73,
Chuck  
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k7pp
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« Reply #1 on: October 23, 2013, 11:24:20 AM »

If you do add wires,  you're not going to run afoul of any electrical Inspectors, are you Chuck?

Just wondering....

Pete, K7PP
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aa5wg
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« Reply #2 on: October 23, 2013, 11:27:55 AM »

Hi Pete,

Great question.  I hope not.  I will look into this.

73,
Chuck
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KA8WTK
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« Reply #3 on: October 23, 2013, 01:32:00 PM »

How about this:  http://newsuperantenna.com/

Put it on the tripod they sell and have the counterpoise wires on the floor. Should fit under a 9' ceiling.

Bill
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Bill KA8WTK
nq5t
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« Reply #4 on: October 23, 2013, 03:28:29 PM »

If there's a balcony, a Buddipole ought to be a reasonable option, too.

I'm thinking about taking one (and my K3) along on the next hotel vacation or family visit to Savannah or to the inevitable retirement home cubicle.

Years ago I lived in a fairly large first floor apartment in Dallas.  I wrapped a wire around the entire ceiling perimeter for an antenna, and a wire along the floor boards for a counterpoise, fed the IC-745 to a tuner and hoped for the best.  It sort of worked, although RF noise was horrible almost everywhere.  I think something like a Buddipole out on the patio would have worked a lot better, and actually been a lot less trouble ...

Grant NQ5T
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wa3dsp
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« Reply #5 on: October 23, 2013, 06:28:27 PM »

You want to embed an antenna in the studs? That sounds dangerous. Even at low (100W) power levels you could have very high RF voltages along an antenna.  You would have to insulate it from the wood and there would be places where it would cross power lines and other utility connections.  Then they are going to put insulation in there. Will it be aluminum faced? It sounds to me like a not so good idea. I am sure an inspector would have some questions also.
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aa5wg
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« Reply #6 on: October 23, 2013, 08:18:30 PM »

Bill, thank you for the newsuperantenna.com link.

We cannot put up an outdoor antenna.

WA3DSP, what if I put the antenna inside grey pvc pipe?

Chuck
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wa3dsp
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« Reply #7 on: October 23, 2013, 10:15:53 PM »

Chuck,

  Well that might help but not sure if it would satisfy an inspector. Also what kind of covering is on the outside? If it's aluminum siding it would not work. I suspect it is vinyl or something that is non-metallic.

Also if the antenna is balanced - a dipole or closed loop feed with open wire line you do not need a ground for RF purposes. If the antenna was mounted outside you would want the antenna to be at DC ground for static and lightning reasons.

This goes back to the same response I gave to someone else who wanted to use an inside antenna. You have to be concerned about power level and RF exposure and also that RFI on receive from local devices and on transmit to local devices might be an issue.
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