Hi, A similar approach is used in the 10811 replacement oscillator setup for the 5065, where a 7474 is used to divide 10 MHz to 5 MHz. Signal conditioning consists of a DC-blocking cap and a pair of resistors to bias the mid-point. The produced noise is at least 10 dB worse than you would expect. This impacts long term stability response as I have reported earlier.
At least using the square-up design in TADD-2 would help, even thought that one won't work for 100 MHz, so it needs a bit of tuning. There are chips that solve this. Cheers, Magnus On 2020-07-18 14:31, Didier Juges wrote: > A long time ago I used a 74AC74 to prescale a 100MHz VCO down to 25, the > 74AC74 was AC coupled to the VCO and the signal was a fraction of a volt. > Worked quite well. > Probably not time-nuts quality but in a pinch it did the job at the time. > Didier > > On Sat, Jul 11, 2020 at 9:37 PM Alex Pummer <[email protected]> wrote: > >> Hi Perrier >> https://www.y-ic.es/datasheet/3b/74F569SC.pdf will work >> 73 >> KJ6UHN >> Alex >> >> On 7/11/2020 3:00 PM, Perry Sandeen via time-nuts wrote: >>> Learned List, >>> On previous posts I was looking for a PDIP package 100 MHz decade >> divider. Reading just the front of the data sheet I thought that the >> 74LS161 would work. Boy, was I wrong. Several members posted that 25 Mhz >> max was its limit. >>> So *on the road again* (sorry Willie) I went on another search this time >> with the correct logic family. >>> It turns out Arrow carries the 74HC161 for less that $1. >>> Additionally I D/L'd the Charles Wenzel Unusual Frequency Dividers PDF >> and discovered a 100 MHz decade divider circuit using 1/2 of a 74HC74 in a >> configuration that will decade divide up to 300 MHz. >>> I'm attaching a copy of the circuit for anyone interested. >>> Regards, >>> Perrier >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
