>>If you want to handle the worst case of an infinite VSWR at 1500 watts, then
>>your PIN diode switch needs to handle 15.5 amps peak of RF at the lowest
>>frequency in use. Similarly, it needs to be able to stand at least 1550
>>volts reverse on the 'off' side of the switch.
>
>? I have never seen a PIN diode with that much piv.
>
MicroSemi HUM 2020 : max PIV = 2000 V
>>For 'typical' HF diodes with
>>recovery times of 10 microseconds, this probably means about 4 amps forward
>>current [I don't have the equations with me here at work].
>>
>>The drivers for this are not a negligible design problem...........neither
>>are getting the PINs.
>>
>? and then there is the matter of dealing with lightning discharges in
>the neighborhood. I had a 5000v doorknob capacitor short from a
>lightning discharge that was over 1000m from my 160m antenna.
>>........
>>Trouble is, having had full QSK, I don't like it anyway......
>>
>? Full QSK on CW can be irritating if the RF gain control is not backed
>off to attenuate extraneous noise, or if the person on the other end is
>making tearfully-boring 5 - 10 min. "lock to talk" monologues instead of
>conversational replies.
>However, like it or not, QSK switching speed in the amplifier is needed
>with modern radios, even if the radio is being operated on push-to-talk
>SSB -- because modern radios begin producing RF in as little as 5mS after
>the PTT switch is pressed. If the amplifier's relay contacts are not
>fully closed when RF arrives, the contacts can not survive. .
>>
>- cheers, Peter
>>
>>
>>
>>--
>>FAQ on WWW: http://www.contesting.com/ampfaq.html
>>Submissions: amps@contesting.com
>>Administrative requests: amps-REQUEST@contesting.com
>>Problems: owner-amps@contesting.com
>>Search: http://www.contesting.com/km9p/search.htm
>>
>
>
>
>Rich...
>
>R. L. Measures, 805-386-3734, AG6K, www.vcnet.com/measures
>
>
>--
>FAQ on WWW: http://www.contesting.com/ampfaq.html
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>Search: http://www.contesting.com/km9p/search.htm
>
>
>
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|