Topband: Antenna switch rating for high SWR?

[Tom W8JI]

Hank's relay suggestion is a good one, because that relay has high voltage 
breakdown from pole to anything else, including the frame. The weakest point 
in that relay is contact to contact on the same pole, which is the least 
harmful if it does arc.

You could have as high as 4000 ohms or somewhere pretty high to ground at 
that point with typical antennas, depending on feedline impedance and 
length, so voltage could be as high as 2450 RMS or 3500 peak, with something 
half (or more than half of that) to ground.
That's probably a worse case at 1500 watts PEP.

There are other ways to do that with some tuners, but that circuit is 
perfectly fine and will work in every case.





----- Original Message ----- 
From: "Hank Garretson" <w6sx at arrl.net>
To: <john at ae5x.com>
Cc: <topband at contesting.com>
Sent: Sunday, October 20, 2013 12:37 PM
Subject: Re: Topband: Antenna switch rating for high SWR?


> For years, I used Tyco DPDT relays. Open-wire feed, who knows what SWR,
> full 1.5 kW.
>
> For example:
>
> http://www.mouser.com/ProductDetail/TE-Connectivity-PB/PRD-11DH0-110/?qs=sGAEpiMZZMtGt%252bn33CgIPz07uLBulijhRYGqdd4PmSw%3d
>
> Mine were 12 VDC units, and with a little research you can probably find
> them.
>
> 73,
>
> Hank, W6SX
>
>
>
> On Sun, Oct 20, 2013 at 9:04 AM, John Harper <john at ae5x.com> wrote:
>
>> Morning all,
>>
>>
>>
>> I am planning to put in a DPDT switch (or relay) to allow me to easily
>> switch from using my 80m dipole as a vertical (T-top) antenna on 160m:
>>
>> http://www.ae5x.com/docs/antennas/160mT.jpg
>>
>>
>>
>> The dipole is fed with 450-ohm ladder line and used 10-80m in that
>> configuration so there is a high SWR on the line. I sometimes use a kw
>> output.
>>
>>
>>
>> I know that T/R switches inside amps are fairly small in physical size,
>> however they are designed to operate into a fairly low SWR load. I have 
>> no
>> idea of what rating of a DPDT switch I would need (per the diagram) in my
>> application - perhaps I'm making a bigger deal of something that isn't so
>> critical.?
>>
>>
>>
>> John AE5X
>>
>> http://www.ae5x.com/blog
>>
>>
>>
>> _________________
>> Topband Reflector
>>
> _________________
> Topband Reflector
>
>
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