There was an attempt to fit voltage dependent resistors (vdr) across the "receiver" (earphone) of telephone headsets to limit audio shock. These were American headsets of an old but very common type (STC perhaps?). When I did a brief test, I increased the voltage applied and found that the waveform across the earpiece gradually became more square. It limited the amplitude of the waveform but the power in the earpiece still increased as it went square. It was probably less of a volume than when the earpiece was unprotected, but it was still very loud. Probably a similar effect to back to back diodes (this is best done with a resistor in series to smooth the response.
David G3UNA > > From: Fred Jensen <[EMAIL PROTECTED]> > Date: 2007/03/13 Tue AM 06:52:30 GMT > To: Elecraft Reflector <elecraft@mailman.qth.net> > Subject: Re: [Elecraft] AGC Independent S-Meter? > > Ron D'Eau Claire wrote: > > >For CW signals the solution was easy. One added a "hard limiter" to the > >audio channel. If a really strong signal was encountered without warning, it > >was clipped of at some preset maximum volume (below the threshold of pain, > >hopefully). Most operators used the limiter at all times in case a huge > >signal came on frequency. > > > Commercial CW ops wore their phones somewhat forward on their ears to > protect them against very strong signals [like being called by a ship > right off the coast 15 miles from your rx site]. In the mid-50's as a > 16-yr old brand new relief op, I have a very distinct memory of being > whacked on the side of my head by my "mentor" standing behind me when I > put the cans on directly over my ears. I still remember the raspy note > on strong signals. Wasn't all that bad a sound, actually. Despite the > limiter however, the beat "note" still got louder a signal got > stronger. My guess is that as the clipping became deeper, the beat note > gained more and more spectral garbage and it just sounded louder. I > might be wrong, however. That's happened one or two times in my life. > > ----------------------------------------- Email sent from www.virginmedia.com/email Virus-checked using McAfee(R) Software and scanned for spam _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net 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
