I have built many 1/2 wave verticals
and also zepps. It is not clear from
your ASCII schematic if you are showing
the coil going to ground, but IMHO it
should NOT go to ground. The circuit
values for "LOW C" look reasonable to
me. The matching is always somewhat
empirical. I have no idea what he is
talking about wrt the "HIGH C" values.
The loss in the coil will be several
percent. I used a 6 inch diameter coil
wound with 1/4 inch copper tubing on
80 and 40 for a number of years in
this configuration without overheating.
It's not that the coil is lossless; it
is just a big heat sink so it doesn't
overheat. BTW, the voltage is only
"several" 1000's of volts, depending
on the impedance. No way is it going
to be 10,000 volts (for legal power
anyway :-)
Rick Karlquist N6RK
richard@karlquist.com
www.n6rk.com
www.karlquist.com
> -----Original Message-----
> From: towertalk-admin@contesting.com
> [mailto:towertalk-admin@contesting.com]On Behalf Of RCARIELLO
> Sent: Wednesday, August 07, 2002 7:23 PM
> To: Towertalk@contesting.com
> Subject: [Towertalk] Matching unit for 1/2 wave verticals
>
>
> Hello to all and Hello to Dink,
>
> How this all started:
> A few days ago Dink, N7WA requested information on the
> possible interaction
> of closely spaced full size 1/4 wave verticals for 80 and
> 40 meters. I
> suggested to put up a single vertical for 80 meters and
> feed it as a 1/2
> wave vertical on 40 meters.
>
> Dink, N7WA is having trouble finding the information on how
> to do this so
> here it is. The values are taken from ON4UN's Low Band
> DXing first and
> second edition.
>
> One capacitor and one coil are needed which are in series
> with each other.
> The configuration is called a tank circuit.
>
> * Point going to antenna
> *
> *
> **********
> * *
> C C
> A O
> P I******** Tap To Coax To Radio
> A L
> C *
> I *
> T *
> O *
> R *
> *********
> *
> *
> * Ground or radials and shield of coax
>
> HIGH L VALUE
>
> BAND C L
> 40M 40pf 13uh
> 80M 80pf 24uh
> 160M 160pf 49uh
>
> HIGH C VALUE
>
> BAND C L
> 40M 250pf 1.9uh
> 80M 500pf 3.8uh
> 160M 1000pf 7.6uh
>
> I can't seem to locate the formula for the voltage being
> produced but it is
> very high. I believe it to be around 10,000 volts for 1500
> watts output. I
> believe the High-C configuration will be less loosely do to
> the small values
> used in the coils. I have only used the High-L values for
> 160 meters.
>
> Rich AA2MF
>
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