Neil McKie <[EMAIL PROTECTED]> wrote: > I still have one here - is a T1411A Mark XII which is a 12 Freq > carrier squelch, duplex radio. SNIP > Expected receiver sensitivity is 0.7 uv SNIP
I sold my last Mark XII/T44MSN/T1411/etc at the Rickreal ham swap meet several years ago. I had a lot of trouble getting the receivers to meet spec, & usually had to settle for about 1.0 uV. That was typical of receivers in mobile telephone service, which usually were listening to very strong (possibly simulcast) transmitters. In typical land mobile, such receiver sensitivity was usually unacceptable in a quality system. I think, in that era of equipment, a person who wanted to be duplex would have been FAR better off to use a Motrac or Mastr Pro & modify it for full duplex operation with seperate antennas. (Which is what you did, Neil - I saw both your radios!) The other problem with those radios, was the transmit PA. It was a MSN 45 watt 150 MHz transmitter with a varacter tripler on the final output. Not very efficient & slightly tricky to tune!! Also, the tuning of the varactor was (of course) a capacitor & a metalic tuning tool was basically needed for the necessary strength required to turn that capacitor. If you happen to accidentially short across the capacitor plates with your tuning tool, you would blow the varactor diode. Last time I checked probably 10 years ago, the cost of that diode was about $145 dollars using my discounted pricing at Motorola!!!! Rather than buy a new diode, I waited until the next Dayton Hamvention where I bought a whole identical radio for about $10 or $20. That night K7LJ & I pulled out the varactor stage & trashed the rest of the radio. The only other thing good in those readios was that they had a tunable harmonic filter which worked well for using as a front end filter on frequency agile radios. Example: a 440 MHz remote base to cover a 10 MHz operating range but filter out signals on other bands or more than 20 Mhz away. Yahoo! Groups Links To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
