[Boatanchors] Coax Switches and Wire Antennas

[D C *Mac* Macdonald]

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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