> Jos said;
>
> >Why dont we see switching systems based on pindiode, for input ( 100 w )
> >must be possible nowadays.
>
> I haven't seen any PINs that will handle more than 1500 volts.
> Additionally, you'll need 10 microsecond or so reverse recovery time to
> handle 160metres. Plus the tank circuit circulating current can easily hit
> 10 or 20 amps, so the PIN would have to have a substantial DC through it,
> at least at the lower frequencies.
>
> ::This doesn't make a lot of sense. PINs are used in the 50 Ohm path, not
> the plate (hi-Z end) path, and normally even at 1500W output with 3:1 VSWR
> would never see more than 821Vpk worst-case. PIN diodes don't have any
> reverse recovery time, that's a characteristic of a bipolar device like a
> rectifier. A PIN is a current-controlled resistor and doesn't rectify
> anything assuming it has long minority carrier lifetime, which they all do
> as part of the PIN design. (WB2WIK)
>
>
> By the time you've provided the necessary RF chokes, the expensive diodes,
> the big DC supply and sorted out the bypassing, ceramic switch wafers are
> cheaper, smaller and more reliable.
>
> ::Possibly true for high-power applications, but then PINs are used
> everywhere as RF switches from low frequencies to microwaves in portable
> equipment having no relays or electromechanical switches at all, and are
> used to switch the BP filters in most modern amateur transceivers, since
> they occupy little space, are inexpensive and very reliable at the 100W
> level -- and they don't rectify and potentially generate IMD products like
> switching diodes (P-N) do. (WB2WIK)
>
> 73
>
> Peter G3RZP
>
>
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