The phone company is responsible for that illogical 3 kHz upper limit. The consonant sounds are missing unless you go above 4.4 kHz( 5 kHz is a good compromise).
Joe W4AAB ----- Original Message ----- From: Gary Blau <[EMAIL PROTECTED]> To: Discussion of AM Radio <[email protected]> Sent: Friday, September 24, 2004 11:20 PM Subject: Re: [AMRadio] Frequency Response > IMHO, the best approach is to terminate the mod xfmr (or any audio xfmr) > for best transient (square ware) response of the modulated envelope, not > just an arbitrary upper frequency. > Adjust for best stability, least overshoot and ringing on leading edges, > and the least tilt. Check it at mid freq's, say 1khz, as well as low > (50hz) and high (5khz). It's easier to see the tilt on the low end, and > the overshoot on the midrange. All of these disturbances rob modulation > power from you, as you have to reduce average modulation level to keep > the peaks from overmodulating. > > Cleaning it up will help maximize modulation control, sometimes as much > as several db. This in turn increases potential average loudness which > is the name of the game. > > The best place for audio bandwidth control/limitation is in the low > level audio chain. > As to where to roll it off, I'd suggest 5khz, but I like to make it > variable depending on conditions. > With only 3KHz you might as well be on SSB. > > g > > > Edward B Richards wrote: > > > > Tom; > > > > I believe the standard for communications is 300 to 3000 CPS +/- 3 dB. > > > > On Fri, 24 Sep 2004 14:54:49 -0800 "Tom Elmore" <[EMAIL PROTECTED]> writes: > > > I am in the process of restoring a Stancor 60-P transmitter to > > > service. I > > > have replaced all the capacitors in the power supply and in the > > > audio > > > amplifier sections. I would like to terminate the modulation > > > transformer > > > with the correct resistance and check for frequency response on my > > > scope. > > > What is a good ballpark response that I should use for operating AM > > > in the > > > amateur bands. > > > > > > Thank You > > > Tom Elmore KA1NVZ > > > Anchorage Alaska > > ______________________________________________________________ > AMRadio mailing list > Home: http://mailman.qth.net/mailman/listinfo/amradio > Help: http://mailman.qth.net/mmfaq.html > Post: mailto:[email protected] >
