[Elecraft] KAT 500 and open wire
Wes Stewart
wes_n7ws at triconet.org
Mon Jan 7 10:49:15 EST 2019
With all due respect, you don't say what acceptable loss is. Of course, you can
match whatever the impedance is, most tuners will match an open circuit because
their internal losses allow it. But it can be a fallacy that, "The line loss is
so low it doesn't matter." Absent voltage breakdown, line loss increases
because of the increased circulating current resulting from operating at
elevated SWR. That increased current is an issue in some baluns and tuners as
well. *All* of these components must be considered when evaluating an antenna
"system." Considering only one part in isolation is fraught with danger.
Try running that 102' long "G5RV" up 50' on 160 meters. Feed it with 100' of
Wireman 553 "low loss" ladderline. The 0.1 dB matched loss turns into over 13
db at the input and that's without considering tuner loss. (Source: EZNEC and
TLDetails)
Wes N7WS
On 1/6/2019 3:15 PM, K9MA wrote:
> The really attractive thing about open line, and even window line, is that its
> loss is so low you can use it at a very high SWR, and take care of the
> matching at the station end. This is especially useful for multi-band
> antennas. The famous G5RV, for example, will work just exactly the same fed
> with window line and a tuner as it will with the usual matching section.
>
> 73,
> Scott K9MA
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