Hi Tony, An old Motorola app. note, AR510 covers the SWR topic. It is a reprint of an article from the February 1991 issue of "RF Design" magazine. A simple diode level detector should be suitable for the overdrive/ALC function. 73 & Good morning, Marv WC6W http://wc6w.50webs.com/ -- "ANTHONY JAPHA" wrote: I'm building the EB104 600 watt solid state amp. described in June '06 QST. I'm concerned about operating into a high (or moderate) SWR, and thought that an SWR protection circuit would be a useful additon to the amp. Also an overdrive protection circuit would be nice. Can anyone point me to a suitable circuit or 2? Many thanks for any advice and 73, Tony, N2UN _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps ________________________________________________________________________ Try Juno Platinum for Free! Then, only $9.95/month! Unlimited Internet Access with 1GB of Email Storage. Visit http://www.juno.com/value to sign up today!