Chuck Thanks and indeed I do need filters that I have not experimented with and in that respect this would be more like some of the circuits discussed here on time-nuts. I am using nice controlled delay lines and at $66 each thats pretty un-attractive. But hey when you get them for 50 cents at a hamfest you can get crazy. Kind of kicking my self as I think the guy had more. Wasn't sure what to do with them. So the next step would be a 5 Mhz notch. Regards Paul WB8TSL
On Fri, Feb 20, 2015 at 11:28 AM, Chuck Harris <[email protected]> wrote: > Hi Paul, > > It isn't that it is bad, it is just that 5 and 15MHz products at > 8 to 10dB down isn't very encouraging. > > To make decent use of this technique, I believe that you would have > to install 20 to 30dB of 5MHz rejection, and a 10MHz low pass filter > in the output circuitry.... > > And, that is in addition to making a simple very stable 90 degree > phase shifter. > > The 5MHz rejection filter is necessary to prevent phase anomalies > from appearing due to the beating of the doubled 5MHz fundamental > with the XOR gate created 10MHz signal. > > Any time you add filters, you are adding temperature dependent phase > shifters to your circuit. > > -Chuck Harris > > paul swed wrote: > >> Experimenting with a 74ls86 XOR doubler for 5 to 10 Mhz. Typically this >> would use a 90 degree phase shift to the other gate. The gate acting as a >> mixer to produce 10 Mhz. >> The reason to experiment is that I have noticed most of the doubler >> discussions take a 5 Mhz square wave filter it to a sine wave, feed it to >> a >> multiplier scheme and then filter the output. The 7486 method eliminates >> one of those processes. >> I have accurate delay lines I can adjust in 2 ns increments (Allen >> Aviation >> lump LC). >> The output is a semi asymmetrical square wave due to some gate timing I >> need to deal with if possible. >> Setting the delay taps to 90 degrees produces a 10 MHz output with 5 and >> 15 >> Mhz 8-10 db down. Lots of other higher frequency outputs. At this point I >> have no filtering on the output of the 7486. >> Purposely mis-adjusting the taps sets either the 5 Mhz or 15 Mhz level >> higher. >> >> Other noise and such are many DB down 50 plus. >> Why is this a bad method as compared to our typical time-nuts discussions? >> Regards >> Paul >> WB8TSL >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/time-nuts >> and follow the instructions there. >> >> _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
