> I really don't care whether people chose to modify their old AM > transmitters to "improve" sound quality, as they can do whatever they > want with their radio. What does bother me a little is when people use > words like "nasty" and "awful" to describe the audio quality of some > classic transmitters, as if thedesigners of the day were not smart > enough to design a decent transmitter. > > At the time these transmitters were built, the goal of amateur pone > operation was effective radiotelephone service. Human speech falls into > the range between 300 and 3000 Hz. There are sounds outside this range, > but they do not contribute to intelligibility. So, in order to make the > best use of the power available, the bandwidth didn't need to be more > than 4Khz. The next logical step in the quest for efficient use of > available power was SSB, which has an equally "nasty" sound but does the > intended job quite well.
But, then, what's the point of running AM? If all you are looking for is "efficient use of available power", why not just run space-shuttle quality SSB and be done with it? It wasn't a matter of the designers of those rigs not being smart enough to design a decent sounding transmitter. Many of those stock "nasty" sounding rigs were designed with cost in mind, more than intelligibility or natural voice quality. Others were trying to climb onto the "communications quality" bandwagon that became all the rage during that era, with the advent of SSB. Many of the AM operators of that era were watering at the mouth to convert to SSB, but simply couldn't afford to buy the commercial equipment that was available at the time, and didn't have the technical know-how to build their own SSB rigs. The original stock Collins KW-1 sounds pretty good. Maybe not quite broadcast quality, but very good "amateur radio quality". Later production runs were modified for "communications quality", and sound more like a phone patch from a land-line telephone using a carbon microphone. Collins intentionally used under-sized coupling capacitors between stages, and by-pass capacitors to limit both high frequency and low frequency response. These later models sound more like an ART-13 or ARC-5 military transmitter than even classic "amateur radio quality" audio, let alone anything near broadcast quality. I helped Jay, W5JAY modify his late-model KW-1 back to the original Collins design, and the audio quality improvement was like night over day. Don k4kyv _______________________________________________________________ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ ______________________________________________________________ Our Main Website: http://www.amfone.net AMRadio mailing list Searchable Archives: http://www.mail-archive.com/[email protected]/ List Rules (must read!): http://w5ami.net/amradiofaq.html List Home: http://mailman.qth.net/mailman/listinfo/amradio Post: [email protected] To unsubscribe, send an email to [email protected] with the word unsubscribe in the message body. This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
