At 5/6/2010 08:22, you wrote: >At 07:55 AM 5/6/2010, Stanley Stanukinos wrote: > > > > > >I must be missing something, there are several MFG of > >encoders/decoders still around. You are correct on the stability > >issue. You will find it much less frustrating to just buy off the > >shelf or get the one for your radio than trying to build one that is > >stable. Oh there is the cost of the new ones so that has to be figured in. > > ><----We have CML Micro MX-828s in stock if the OP is interested in >purchasing one or two (or 3 or 4 <g>). Contact me offlist about them. > >And yes, NE567's (or their derivatives) were never designed for use >as a CTCSS decoder as they cannot possibly maintain the frequency >stability (nor have the narrow bandwidth) required for that use.
Actually, the chip itself is inherently just stable enough - ~+/- 1%. Just have to use stable timing components. They also can be made as narrow as you want by selection of the loop filter capacitor value. The problem is the decode time @ 1% BW, which can be as long as 2 seconds @ 100 Hz according to the datasheet. Bob NO6B
