I dont know what kind of an isolatuion transformer you guys are using, i
come from a vintage view point where no ferrite or coax is ever used
except to go from the transmitter final coil to the antenna coil.
coupling is just some #14 insulated wire around the whatever coil i am
going from to a wiinding on whatever coil i am going to, loop coupling
everywhere, even in my receiver designs
for antenna tuning make the coil the length needed to get an swr =1.0x
or so, no matter what size of variable cap you need to resonate
mike w7dra
On Thu, 8 Dec 2011 18:41:41 -0800 "Rick Karlquist"
<richard@karlquist.com> writes:
> W0UCE wrote:
>
> > * The ONLY means of achieving the required degree of
> Isolation is to
> > use the Isolation Transformer as specified by K2AV
> > * Tests using 1:1 Baluns and Line Isolators have ALL FAILED
> - you
> > waste RF Power, Time and Money unless the specified xfmr is
> installed
> > * DO NOT attempt to use Insulated Window Line for the FCP -
> We already
> > tried it and it does not work - too lossy
> > * Use #12 Bare wire for the FCP elements - Moisture gathers
> on
> > insulated wire and detunes the FCP
>
> I haven't built this system, but the suggestions above make sense.
> I have been trying to encourage using transformers instead of
> baluns
> on 160 meters for years, but it's a tough sell to overcome the
> balun
> habit. The tendency for loss in the open wire line also makes
> sense. It is well known that window line is lossy when wet.
> What is new here is that the Q is so high that you can't even
> use insulated wire for open wire line. It would be interesting
> to see if teflon insulated wire worked OK. The electric field
> is maximum right at the conductor surface, so the insulation has
> a considerable effect on characteristic impedance, thus I could
> imagine it would affect loss too. I am feeding my vertical
> using 850 feet of open wire line with XHHW insulation (whatever
> that is made out of). It would be interesting to measure the
> loss on a rainy day and see how much it increased. It's only
> a few tenths of a dB when dry (the wires are 4 AWG aluminum).
>
> Rick N6RK
>
> _______________________________________________
> UR RST IS ... ... ..9 QSB QSB - hw? BK
>
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