I have a 50 MHz oscillator I want to measure, and I have a TICC and a 10 MHz source (to run the TICC) and a good 1pps.  I assume that if I divide the 50 down to 5 (e.g. with the TADD-2) I can do the measurement.  The question is whether the TADD (or some other inexpensive off the shelf thing) can handle that high an input frequency. Or, is that pushing the PIC beyond its limits? Same sort of question for 100 MHz.

Hi Jim -- The PICs used in the TADD-2 and TADD-2 Mini are rated for a maximum external clock of 20 MHz. So, 50 MHz probably won't work, unless maybe you set an ice cube on top of the IC. :-) John ---- On 9/25/24 20:51, Jim Lux via time-nuts wrote: > > > > > I have a 50 MHz oscillator I want to measure, and I have a TICC and a 10 MHz source (to run the TICC) and a good 1pps.  I assume that if I divide the 50 down to 5 (e.g. with the TADD-2) I can do the measurement.  The question is whether the TADD (or some other inexpensive off the shelf thing) can handle that high an input frequency. > Or, is that pushing the PIC beyond its limits? > > Same sort of question for 100 MHz. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hi Jim, Well, you might be able to push the input-stage to support 50 MHz, but not the PIC. However, if you manage to divide by 4 through a break-in, you may be in luck. BTW. Some old reports show that odd division numbers performs worse than even division. I can't recall seeing a conclusive analysis on that, but I think it lies in how noise folds around, which have been analyzed better in the last years. However, doesn't the TICC support 50 MHz? If so, you could use your TADD-2 on the 10 MHz and get your start time-base there to trigger the TICC and then use the 50 MHz as stop. If 50 MHz too high, divide down until in range, but not much more. Cheers, Magnus On 2024-09-26 02:51, Jim Lux via time-nuts wrote: > > > > I have a 50 MHz oscillator I want to measure, and I have a TICC and a 10 MHz source (to run the TICC) and a good 1pps.  I assume that if I divide the 50 down to 5 (e.g. with the TADD-2) I can do the measurement.  The question is whether the TADD (or some other inexpensive off the shelf thing) can handle that high an input frequency. > Or, is that pushing the PIC beyond its limits? > > Same sort of question for 100 MHz. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hi Even with an ice cube …. not so much. You don’t just want it to divide. You want it to divide and be reasonably low noise. Likely cheapest alternative would be some sort of add on board done at JLPCB. (so no, not off the shelf ….). Bob > On Sep 25, 2024, at 9:30 PM, John Ackermann N8UR via time-nuts <time-nuts@lists.febo.com> wrote: > > Hi Jim -- > > The PICs used in the TADD-2 and TADD-2 Mini are rated for a maximum external clock of 20 MHz. So, 50 MHz probably won't work, unless maybe you set an ice cube on top of the IC. :-) > > John > ---- > > On 9/25/24 20:51, Jim Lux via time-nuts wrote: >> >> I have a 50 MHz oscillator I want to measure, and I have a TICC and a 10 MHz source (to run the TICC) and a good 1pps. I assume that if I divide the 50 down to 5 (e.g. with the TADD-2) I can do the measurement. The question is whether the TADD (or some other inexpensive off the shelf thing) can handle that high an input frequency. >> Or, is that pushing the PIC beyond its limits? >> Same sort of question for 100 MHz. >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe send an email to time-nuts-leave@lists.febo.com > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

I've had 20MHz PICs clocking OK at 35MHz at room temperature, and IIRC one went OK up to 43MHz. Andy www.g4jnt.com On Thu, 26 Sept 2024 at 16:38, Bob Camp via time-nuts < time-nuts@lists.febo.com> wrote: > Hi > > Even with an ice cube …. not so much. > > You don’t just want it to divide. You want it to divide and be reasonably > low noise. > > Likely cheapest alternative would be some sort of add on board done at > JLPCB. > (so no, not off the shelf ….). > > Bob > > > On Sep 25, 2024, at 9:30 PM, John Ackermann N8UR via time-nuts < > time-nuts@lists.febo.com> wrote: > > > > Hi Jim -- > > > > The PICs used in the TADD-2 and TADD-2 Mini are rated for a maximum > external clock of 20 MHz. So, 50 MHz probably won't work, unless maybe you > set an ice cube on top of the IC. :-) > > > > John > > ---- > > > > On 9/25/24 20:51, Jim Lux via time-nuts wrote: > >> > >> I have a 50 MHz oscillator I want to measure, and I have a TICC and a > 10 MHz source (to run the TICC) and a good 1pps. I assume that if I divide > the 50 down to 5 (e.g. with the TADD-2) I can do the measurement. The > question is whether the TADD (or some other inexpensive off the shelf > thing) can handle that high an input frequency. > >> Or, is that pushing the PIC beyond its limits? > >> Same sort of question for 100 MHz. > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@lists.febo.com > >> To unsubscribe send an email to time-nuts-leave@lists.febo.com > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe send an email to time-nuts-leave@lists.febo.com > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

Jim, If you do have a tinyPFA or nanoVNA-H4 to convert to tinyPFA you can input 10 MHz in one input and 50 MHz in the other. The 10 MHz must be a square wave and you set the measurement frequency to 50 MHz For best results you may have to increase the 10 MHz input level to 0 dBm Erik On Thu, Sep 26, 2024, 03:19 Jim Lux via time-nuts <time-nuts@lists.febo.com> wrote: > > > > > I have a 50 MHz oscillator I want to measure, and I have a TICC and a 10 > MHz source (to run the TICC) and a good 1pps. I assume that if I divide > the 50 down to 5 (e.g. with the TADD-2) I can do the measurement. The > question is whether the TADD (or some other inexpensive off the shelf > thing) can handle that high an input frequency. > Or, is that pushing the PIC beyond its limits? > > Same sort of question for 100 MHz. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com