I should add that it doesn’t change needing a robust switching mechanism to
handle the voltage, but at least resolves the issue of conductors to switch a
relay being in the vicinity of the antenna.
73, kelly, ve4xt
> On Oct 17, 2016, at 12:10 PM, Kelly Taylor <ve4xt@mymts.net> wrote:
>
> 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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>
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