> 2 ALC has its problems and thus not always connected, but > everyone uses PTT which can be very easily disabled (allow > the rig to self protect) or tx inhibit, tx enable, or others?
I STRONGLY disagree ... I WANT a graceful foldback if the antenna SWR is slightly out of range. 10% reflected power should not take an amplifier off line. However there should be some way to cause the exciter to reduce its power output so the amplifier does not generate voltages or currents that will cause the demise of the active devices. Unless one has an amplifier and exciter that share a common control microprocessor with data feedback or the amplifier has an extremely sophisticated and FAST attenuator in the drive line, ALC (e.g., an external gain control) is the appropriate means of reducing power gradually. Sure, if the reflected power is so high that it indicates an antenna failure (50% reflected power), the appropriate action is to disable the amplifier and potentially even the exciter but that's over the top for 10% reflected power (2:1 SWR) or even 20% reflected power (3:1 SWR). 73, ... Joe, W4TV > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of David Cutter > Sent: Monday, December 03, 2007 5:55 PM > To: Elecraft Reflector > Subject: [Elecraft] linear amp shutdown (was ALC) > > > In my view there are 2 issues here: > > 1 in my view the amplifier should be self-protecting > against overloads, eg > antenna fault (I am mindful of virtually any other equipment > which must be > tested by law with overload conditions) > > 2 ALC has its problems and thus not always connected, but > everyone uses > PTT which can be very easily disabled (allow the rig to self > protect) or tx > inhibit, tx enable, or others? > > ALC is an analog signal for gradually reducing drive, which > might not be > appropriate for shutdown. > > David > G3UNA > _______________________________________________ Elecraft mailing list Post to: [email protected] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
