Bob, yep, I remember the Motrac and other rigs of the 60s and before and about all used heaters. However, very very few use these rigs today. Besides with the tube voltages one can get killed in these critters, hi.
Again few rigs today, even the older rigs used like the Micor and GE Mastr series use heaters. Heaters in rigs is a thing of long ago past. 73, ron, n9ee/r >From: "Bob M." <[EMAIL PROTECTED]> >Date: 2007/07/12 Thu AM 07:36:18 CDT >To: [email protected] >Subject: Re: Re: [Repeater-Builder] Re: crystal/channel element compensation.. > >I beg to differ. > >Few MODERN commercial rigs (built since the 1980s) use >heaters, but prior to the Micor, almost all of the >vacuum-tube two-way radio sets definitely used crystal >heaters. I have the burn marks on my fingers to prove >it. The temp was usually around 85C and the units >operated from 6 or 12 volts which was always available >as a filament voltage. The GE units could hold two >crystals and used an 8-pin octal-style plug-in module. >The Motorola units could hold one crystal and used a >4-pin rectangular module. When ordering crystals from >ICM, one could specify whether the unit was to be >heated or not, and if it required large pins (to plug >directly into the radio's socket) or small pins (to >plug into the socket inside the heater). I'm not sure >you could call these "ovens" as they used a mechanical >thermal switch to control the temperature and the >crystals were firmly mounted inside the units. > >Crystal ovens were very common in older (tube-era) >broadcasting equipment, however in the more modern >synthesized units they might have a TXCO or even an >OXCO for a reference oscillator (depending on how >cheap the manufacturer was). AM broadcast stations >rarely use ovens these days; the crystals are stable >enough to keep the carrier within +/- 10 Hz (about 10 >ppm) which is better than the FCC requirement. > >Bob M. >====== >--- Ron Wright <[EMAIL PROTECTED]> wrote: > >> Few commerical rigs use a heater to stablize the >> frequency. Some see it in applications such as >> broadcasting where very tight, much tighter than >> commerical, frequency is required. >> ... > >__________________________________________________________ >Be a better Globetrotter. Get better travel answers from someone who knows. >Yahoo! Answers - Check it out. >http://answers.yahoo.com/dir/?link=list&sid=396545469 > Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
