[Elecraft] EFHW clarification

[Fred Jensen]

Guess I missed that in your post, sorry.  Any conductor of any length 
will radiate, resonant or not ... provided you can get your TX to feed 
power into it.  In all cases, the far end of the conductor is an open 
circuit [High E, low I, High Z] The impedance at the feed end will be a 
complex number.  If the conductor is resonant, the reactance will be 
zero.  If it is not resonant, it will be non-zero and either inductive 
or capacitive, and one more component your ATU has to deal with.  
Elecraft ATU's [even the simplest KX1] can deal with a fairly wide range 
of complex impedances ... with a 9:1 transformer, you should be OK.

Yes, the outside surface of the coax shield will act as a counterpoise.  
Even without coax [direct feed], the radio chassis, headphone cable, 
battery, and you will usually suffice although hanging a few feet of 
wire off your lap from the shield of the BNC may help.

If you do use coax, and you really think you need a common mode choke, 
put it at the rig, not the transformer.  Otherwise you don't have much 
counterpoise. [:-)

Hope this is closer to answering your questions

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County


On 2/8/2017 4:14 PM, Dan Presley wrote:
> Thanks for the replies so far. Just to clarify-I plan to use the built in auto tuners in my KX2 and 3, so hopefully they can handle the job. I already have a good 9:1 transformer which should work. The primary question is the advantage to the EFHW as opposed to a true random length (not a halfwave at desired freq) with a counterpoise. It sounds like the high current point is a quarter wave from the feedpoint which could be an advantage from the random length. I’ve also seen a variety of ideas on the proper length of coax to use with an EFHW, which as I understand will act as a counterpoise. I now have one of the nice lightweight SOTA poles which would be good with whatever wire I go with. Waiting for some decent weather in the Pacific NW  :))
>
>
> Dan Presley  N7CQR
> n7cqr at arrl.net
>