[Amps] Overengineering a pi-network bandswitch

R.Measures r at somis.org
Wed Sep 1 02:44:50 EDT 2004


On Aug 31, 2004, at 11:11 PM, Angel Vilaseca wrote:

> Hi,
>
> I am building a kilowatt shortwave amp.
> I need a switch to short-circuit a variable part of the coil in the
> output pi-network to tune into every amateur band.
>
> Unfortunately, heavy-duty, ceramic wafer rotary switches are hard to
> find nowadays.
>
> On the other hand, I have several 10-A, 220 V mains rocker switches,
> which (I think) could handle the currents and voltages. RF behavior
> should not be very different from a rotary switch (would it?). I am
> planning to use an array of these instead of a rotary switch. Some
> clever use by the operator (me!) would be the only difference. But
> ruggedness would be enhanced.
>
> Has anyone already tried this?

No, but it should work if the open switch contacts can withstand 
1.5-times the anode supply V and the switch's current rating is 4-times 
higher than the RF circulating current in the tank.  .
>
>
> Best 73
>
> Angel Vilaseca HB9SLV
>
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>
>
Richard L. Measures, AG6K, 805.386.3734.  www.somis.org



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