[Elecraft] KX-1 antenna matching

[stan levandowski]

Rick, thanks for your input from way up there in Alaska!  The KXAT1 
manual suggested (actually "stated") 1/8 wavelength minimum 
counterpoises per band and that's where the 8 foot wire for 20M came 
from.  Also, my counterpoises have not always been on the earth; 
sometimes raised by a foot or so. 


I think I'll scrounge up some wire, some alligator clips and make up 
some "extensions" like you described and do some testing tomorrow.  I 
also like your idea about clipping it to a metal picnic table.  Today, I 
was operating from a very large (8 foot) and heavy wrought iron picnic 
table on my rear deck.  Never thought about trying that!  I've got a 
nice large central air compressor nearby also but that might introduce 
RFI.  Still, might be worth a quick clip-up to see.


Thanks, Stan WB2LQF


On Fri, Jun 09, 2017 at 07:22 PM, Frederick Dwight wrote:

> Stan,
>      I have used a kx 1 for thousands of QSO’s many in the field on 
> 40, 30, and 20 meters.  My usual field antenna is a 26 ft piece of 
> wire and one or two 17 counterpoise wires.  If the counterpoise 
> (radial) wires are laying directly on the ground, usually I get a very 
> good match on all 3 bands.  If part or all of the counterpoise/radial 
> wire is elevated, then sometimes I clip on an extension of about 8 
> feet to get a better match if the SWR is higher than about 2:1 
> (probably only necessary on 40 meters sometimes).  Occasionally for 40 
> meter elevated counterpoise operation I have even used a single 34 ft 
> counterpoise wire if I happen to have one available….not likely when 
> backpacking.  I would just use your 16 or 17 ft counterpoise for 20 
> meters…it might improve your 1.6:1 SWR, however I still have my 
> original PA transistor and have often operated with SWR’s around 2:1 
> or higher, however my goal is to try not to exceed about 2:1. Usually 
> I can get SWR down somewhere between 1:1 and and perhaps 1.9:1 (just a 
> guess) on 40 meters, and often about the same or even slightly better 
> on 20 and 30 meters.  I always carry a 8 ft piece of wire with a big 
> clip on the end.  Often clipping it to a metal picnic table, guard 
> rail, chain link fence, or car body either instead of a radial, or in 
> addition to one and get satisfactory performance.  If I use an 
> elevated counterpoise…then I clip the 8 ft wire onto the end of my 17 
> ft counterpoise for better matching on 40 and possibly 30 meters.  I 
> see no reason to just use a 8 ft counterpoise or radial wire for 20, a 
> 16 or 17 wire should be better on all the bands. Occasionally I lay 
> down two 17 ft radial wires on the ground if I have them and there is 
> room.  Some of my attempts at modeling showed slightly improved 
> performance.  If I have a preferred direction I often lay them down in 
> roughly that quadrant.  The theory is it may slightly help in that 
> direction, but more important it may eliminate a very slight null 
> opposite to the desired direction.  This is my unproved theory only 
> since it would be nearly impossible to measure something like a dB or 
> so.
>            This is usually the only antenna I carry for backpacking, 
> or travel around the US or Europe.  Something like a linked dipole 
> (usually set up as an inverted V) will often perform significantly 
> better, however I much prefer something like the 26 ft wire….5 minutes 
> to set up and lots of time to operate vs. an hour set up and less 
> operating time.
>             Rick  KL7CW   Palmer, Alaska
> Sent from Mail for Windows 10
>
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