[Boatanchors] Coax Switches and Wire Antennas

[Bill Stewart]

Tnx Gary, another good idea...Bill

----- Original Message -----
From: "Gary Schafer" <garyschafer at comcast.net>
To: "D C *Mac* Macdonald" <k2gkk at hotmail.com>, w7qho at aol.com, "K4JYS Stewart, Bill" <cwopr at embarqmail.com>
Cc: boatanchors at mailman.qth.net
Sent: Wednesday, March 30, 2011 7:12:49 PM
Subject: RE: [Boatanchors] Coax Switches and Wire Antennas

A sheet of plexiglass with banana jacks.

73
Gary  K4FMX


> -----Original Message-----
> From: boatanchors-bounces at mailman.qth.net [mailto:boatanchors-
> bounces at mailman.qth.net] On Behalf Of D C *Mac* Macdonald
> Sent: Wednesday, March 30, 2011 4:47 PM
> To: w7qho at aol.com; K4JYS Stewart, Bill
> Cc: boatanchors at mailman.qth.net
> Subject: Re: [Boatanchors] Coax Switches and Wire Antennas
> 
> 
> If you are worried about a flashover why not try
> to find a LARGE manual switch at a flea market or
> hamfest suitable for the bandswitch in a pi-network
> high power amplifier?  Mount it using an aluminum
> bracket on a board and put a nice, big knob on it.
> Could be lots cheaper than a commercial coax switch
> 
> No worries then!
> 
> * * * * * * * * * * *
> * 73 - Mac, K2GKK/5 *
> * (Since 30 Nov 53) *
> * Oklahoma City, OK *
> * USAF, Ret (61-81) *
> * * * * * * * * * * *
> 
> 
> 
> 
> > From: w7qho at aol.com
> > To: cwopr at embarqmail.com
> > Date: Wed, 30 Mar 2011 13:40:24 -0700
> > CC: boatanchors at mailman.qth.net
> > Subject: Re: [Boatanchors] Coax Switches and Wire Antennas
> >
> > Bill,
> >
> > If you plan to use the classic Windom (half wave top section, single
> > wire feeder) the impedance looking into the feedwire "should" be
> > something around 600 ohms. Cut and try required to find the correct
> > tap point on the flat-top and the length of the feed wire and the
> > ground system used also have an effect. Probably OK through your coax
> > switch at the 75 watt level but only for the frequency/band for which
> > the flat top was cut. On harmonic related frequencies (ex. 40M
> > operation on a flat top cut for 75M) the impedance looking into the
> > feedline could be just about anything.
> >
> > For the end-fed case, how long is the wire and what frequency/
> > frequencies are you using? OK for your switch if the feed point is
> > anywhere near a current loop.
> >
> > Dennis D. W7QHO
> > Glendale, CA
> >
> > *****
> >
> > On Mar 30, 2011, at 7:07 AM, Bill Stewart wrote:
> >
> > >
> > >
> > > Good morning all,
> > >
> > > Can a normal coax switch be used to switch single wire fed antennas
> > > such as a long wire or OCF Hertz (windom-a hi imped. antenna), in my
> > > case. No coax feed used, just a wire from the wire antenna thru the
> > > center conductor of the switch and then to the xmtr or tuner. I have
> > > 'heard' that a coax connector presents a 50 ohm 'lump' in the line.
> > >
> > >
> > >
> > > I know this can be done electrically, but just wondering about the
> > > '50 ohm' situation. Tnx for helping with a stooopid question.
> > >
> > >
> > >
> > > 73, Bill K4JYS
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