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Author Topic: Advice on failed Carolina Windom 80M  (Read 2360 times)
KC2NYU
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Posts: 140




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« on: July 06, 2012, 01:22:04 PM »

My second Radio Works Carolina Windom 80M Compact (folded) OCF dipole just stopped working after about 14 months, first one I had lasted about 18 months. I lived in Savannah, Ga where ambient temps do get quite hot. Not willing to plunk down $ for a third. When it worked it did quite well on 80M - 6M, and fit my lot and restricted neighborhood well. From reading eHam reviews on this antenna others have had problems with water intrusion and heat damage to the two non- wire components (balun and line isolator) Wondering if:
1) anyone has rebuilt  one of these Carolina Windoms with purchased or homemade parts (balun and "line isolator)
2) Any recommendations on other commercial OCF Dipoles that would cover 80M- 6M

73 Paul kc2nyu
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K5KNE
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Posts: 65




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« Reply #1 on: July 06, 2012, 08:10:32 PM »

Yes, I recently purchased a 6:1 balun for making an ocf antenna. I think with the wires cut to the design length (about 30% feedpoint) of the length for the feed point - should be the same antenna the expensive one is.

You can buy baluns from W2AU and others.  Look on internet for 4:1 baluns and you will find a source - for about $30 to $40. There are different types and you can spend a lot more.

I would check the balun out carefully before saying it is bad.  You know the wire is not bad - so the connections are sure suspicious. The baluns I have torn open are pretty well water-proofed.  I have one that I tore up the case and just used PVC pipe fittings to re-encase it.

Good Luck,  Walter K5KNE
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KC2NYU
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Posts: 140




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« Reply #2 on: July 07, 2012, 07:25:52 AM »

Walter - thanks for advice. If I could I'd like to use the antenna as cut and just replace the components in the "two tubes". The top one is the Balun and the bottom one Radio Works calls a line isolator. Collectively they refer to this piece of coax that hangs down as a "vertical radiator". So if I replace the top balun with a 6:1 balun, I am thinking the bottom tube is just some sort of RF Choke. Wonder if the Group has any ideas on details of what to replace it with? 

73 Paul
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KC9Q
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Posts: 49




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« Reply #3 on: July 07, 2012, 08:01:30 AM »

Paul,

If you replace the Balun with a two core Current Balun (either 4:1 or 6:1), then you will not need the line isolator (it'a 1:1 choke balun).  Voltage Baluns tend to allow currents to flow on the coax shield.  The line isolator is used to stop the current from traveling down the line to the transceiver.  The design of the two core current balun has the line isolator feature "built-in" so to speak.

Mike
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KC2NYU
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Posts: 140




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« Reply #4 on: July 07, 2012, 09:02:30 AM »

Mike- thanks. My OCF dipole in question is about 50 ft off ground. Does height above ground effect balun rating. So would 4:1 or 6:1 be better?

tnx and 73
Paul
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KC9Q
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Posts: 49




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« Reply #5 on: July 07, 2012, 10:35:08 AM »

Going higher than 50 ft you may need to use a 5:1 or 6:1 Balun.  At 50 ft the 4:1 should do fine.  Installing the OCF straight horizonally will give a close match to approximately 50 ohms using a 4:1 Balun.  By installing it as an Inverted V it will lower the antenna impedance.  This is something you can use to fine-tune the antenna.  (Same principal as a dipole: installed horizontally it will have an impedance around 73 ohms, but when installed as an inveted V it lowers the impedance somewhere closer to 50 ohms).

Mike

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KC2NYU
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Posts: 140




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« Reply #6 on: July 07, 2012, 11:05:22 AM »

So installed as a slightly inverted V, to allow for the sway of the trees, having center at say 45', still use 4:1 of go to 3:1?

Tnx
Paul
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KC9Q
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« Reply #7 on: July 07, 2012, 11:40:37 AM »

Just use the 4:1.

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KC2NYU
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« Reply #8 on: July 07, 2012, 12:43:10 PM »

roger- thanks
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W4IOW
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Posts: 34




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« Reply #9 on: July 07, 2012, 04:56:49 PM »

I have been running an 80 meter Radioworks Windom for over 4 years with out a hick-up. I run 100W only. Contact Jim at Radioworks, he is responsive to emails, and has been helpful to me in the past. His email is on the RW webpage.

Ray
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K2CBI
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Posts: 59




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« Reply #10 on: July 08, 2012, 12:55:39 PM »

I replaced the baluns in my Carolina Windom 80 after I bought a legal limit solid state amplifier - just in case they fried while I was transmitting.  The amp would not appreciate that.  Bob at Balun Designs was very helpful when I chose replacement baluns.  (http://www.balundesigns.com/servlet/StoreFront).

The connectors on the 22 foot section fried on two separate occasions while transmiting (fortunately before the solid state amp).  I replaced the 22 foot coax (RG8) with larger diameter coax (RG8U type) and replaced the UHF connectors and have not had any further problems.

This antenna works well at 45 feet at my QTH.  I run about 1KW.


Mike - K2CBI

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