John’s old idea seems like the perfect application of something in QST a while
back: a pneumatic relay.
A puff of air up a non-conducting piece of tubing would trigger the switch: I
can’t recall if it was latching or not.
73, kelly, ve4xt
> On Oct 17, 2016, at 11:44 AM, john@kk9a.com wrote:
>
> That is a good question. Years ago I thought of building an 80m vertical
> with a relay on top to make it a 160m inverted L at my P40A home but I did
> not know if even a vacuum relay would hold up and I knew that there would
> be RF issues with the control wires running down the vertical. I had never
> seen it done and did not want something likely to fail. If you are just
> changing band segments most manufactures are using switchable loading
> coils at the feed point.
>
> GL
> John KK9A
>
>
> To: towertalk@contesting.com
> Subject: [TowerTalk] Voltage at ends of yogi parasitic elements?
> From: Rob Katz <rob.katz@thelegacycenter.com>
> Date: Sun, 16 Oct 2016 23:09:11 -0400
>
>
> I’m playing with some wire yagis, and I’d like to put relays at the ends
> of the
> parasitic wires to switch the director to a reflector (and vice versa).
> If I’m
> driving the antennas with a full 1.5 KW, what would be the maximum voltage
> that
> I can expect at the ends of the PARASITIC elements? Even a rough estimate
> would be useful, I just need to get a sense of what kind of a relay I would
> need to use.
>
> 73,
> Rob K4OV
>
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