[Elecraft] KX3 horizontal 40 meter antenna loop feed connection - HOW?

[Ross Primrose N4RP]

Ladder line doesn't like to be near "stuff"...  Feed it with coax, even 
with a high SWR on the coax your losses will be negligible over that 
length.  A 1:1 or 4:1 current balun at the feedpoint would probably be a 
good idea, but isn't a deal breaker...

73, Ross N4RP, who needs to get his 160m loop back up before the leaves 
come out ;)

On 4/1/2014 5:26 PM, Esquer Dave wrote:
> Newbie Dave, KX3 owner with built in ATU. I have a loop antenna feed point line question. I know this is not an antenna group but I want something optimized for the KX3 and QRP.
>
> I have installed a 40 meter skywire horizontal loop antenna in my attic, 135 feet in length. I hope to use the antenna on 40-10 meters. I live in a condo complex, fortunately for me, on the 2nd floor. The distance from the feed point to the rig vertically is about 20 ft and about 5 ft horizontally through a ceiling.
>
> Coax or ladder line feed, most say ladder line for low loss?
>
> I am stumped, confused and bewildered about how to feed my KX3. Opinions are ALL over the map with NO consistency. I have researched the Skywire google and yahoo groups and the ARRL docs.  Just tell me what works best for my KX3 and how to do it.
>
> If I feed with 450 ohm ladder line, how do I transition from the ladder line to the rig? Is it antenna ends to 20 ft of ladder line to the balun and then a short stub of coax? What is short, 1 to 5 ft? Do I cut the ladder line long and what do I do with excess? The ladder line has to stay mostly vertical?
>
> I have the BNC to binding post adapter as well. Can I just feed ladder line to the binding posts directly with maybe some kind of strain relief?
>
> It sorta works now with the antenna loop connected to an MFJ913 4:1 balun to RG8X coax to rig. SWR on 40 meters is about 2.0 to 2.2 across the band (low to high) as measured externally before connecting to the rig. Am I good enough? The ATU handles it quite nicely bringing it down to 1:1.
>
> I’ve tried feeding the coax directly, with no balun, but that made the SWR much worse externally, 5:1 and up.
>
> Remember, be gentle to this newbie and TIA,
>
> Dave Esquer, K6WDE
> dave.esquer at gmail.com
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