On (04 Aug 97  08:04:16) Roy Witt wrote to Jeff Edmonson ...
RW>  >> OK Tech-Guy, got a schematic for a simple tone generator
RW>  >> I can use in my FM rig to open the repeater? Only needs to
RW>  >> generate ONE tone, at 146.2 Hz. I could swap in different
RW> 
RW> Two transisters linked for feedback works just fine.  Got the schematic
RW> here somewhere, just need to dig it up.
A XR2206 works just fine - give a sine output too.
RW>  JE> However you decide to come up with the actual tone, remember to
RW>  JE> inject it at the CARRIER level, and not in the audio section.
RW> 
RW> In the deviation section is better.  You can tell when the tone is right
RW> by the amount of deviation in the carrier...
Use the P-N junction of any GP transistor as a varactor diode across
the freq determining element. Or inject it AFTER the pre-emphasis
ckts.
RW> JE> Remember to keep the ouput low enough to not be heard by human
RW> ears,
RW> JE> yet detectable by the repeater reciever.  They're -supposed- to be
RW>  JE> sub-audible ;-)
RW> 
RW> 146.2hzs and higher is audible no matter the output.
As it passes the repeater RX, everything from 300 Hz down is
drastically attenuated making the tone virtually inaudible.
Larry - WA5KBQ
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