[Elecraft] EFHW

[K9MA]

Here's the old trade-off between radiating efficiency and ease of 
matching for an end fed wire. The EFHW is more efficient, because little 
power goes into the ground system, but its high impedance is harder to 
match.  A wire of a different length may be easier to match, but more 
power goes into the ground system, where it doesn't radiate much.  Both 
will work but, I believe, on average the EFHW will be a bit better.  Is 
it worth the trouble?  Who knows?

Antenna discussions have long had a tendency to focus on SWR.  Low SWR 
does not necessarily mean an antenna is effective.  There's an old 
saying, "The SWR of a dummy load is 1:1."

73,

Scott  K9MA



On 2/10/2017 09:56, Don Wilhelm wrote:
> Brian,
>
> If your end fed antenna is actually a halfwave (which is what EFHW 
> means), the answer is no.
>
> The solution for portable work is to use a length that is not a 
> halfwave - 58 feet is known to work well for 40 thru 10 meters when 
> used with a 13 foot counterpoise.  Double the lengths if you want 80 
> meters.
>
> With that antenna and counterpoise length, dispense with the balun for 
> portable operations, and use a BNC to Binding post adapter instead (no 
> coax).
>
> If you need to use a short length of coax, you can put the balun at 
> the end of the coax, and you can try both the 1:1 and 4:1 positions to 
> see which provides the better match.
>
> 73,
> Don W3FPR
>
>
> On 2/10/2017 10:36 AM, Brian Pietrzyk wrote:
>> Speaking of baluns or un-un's... I'm about to assemble a BL2 which is 
>> a 4:1. Will that be enough to bring an End Fed Half Wave (EFHW) 
>> within tuning range of my KX3 ATU?
>>
>> I'm going to be ve3bwp/hi9 QRP week after next and hoping to try a 
>> couple of different length end feds into one of the trees near the 
>> beach. I'll be trying Phone and psk31/JT65/CW an afternoon or two 
>> that week. Anyone interested in a sked email me direct.
>>
> _

-- 
Scott  K9MA

k9ma at sdellington.us