[time-nuts] Squaring Tbolt 10Mhz output

James Fournier james at jfits.ca
Fri Mar 25 01:15:24 UTC 2011


Thanks everyone, i think the key here is to repeat with faster chips.
I appreciate  the everyone's comments.

On Thu, Mar 24, 2011 at 4:26 PM, Bob Camp <lists at rtty.us> wrote:

> Hi
>
> The TBolt is designed to drive 50 ohms on the 10 MHz output. Level is above
> 7 dbm on the ones I have looked at.
>
> Bob
>
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
> Behalf Of Greg Broburg
> Sent: Thursday, March 24, 2011 5:20 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Squaring Tbolt 10Mhz output
>
> what is the output drive circuit and what is the drive
> level / source impedance from the Thunderbolt?
>
> Greg
>
>
>
>
> On 3/24/2011 2:10 PM, Hal Murray wrote:
> >> I'm not sure everything can handle the 10Mhz signal.
> > Bingo.
> >
> > LM339 (National data sheet)
> >    Response time:     0.5 us
> >
> > CD4049B/CD405B (from TI data sheet)
> >    Rise time is 80 ns
> >    Fall time is 30 ns
> > Those are typicals at 5 V with a 5V input signal.
> >
> >
> > The LM399 says "low power" which usually means low speed.
> >
> > I occasionally go "oops" when I sanity check the speed on a circuit I'm
> about
> > to build using HC/LS parts.  They aren't very fast, and the old 4000
> logic
> is
> > even slower.
> >
> > 10 MHz is about the corner for HC.  I use the HC163 (4 bit binary
> counter)
> as
> > an example.  It has a max clock frequency of 25 MHz, so you think "no
> > problems" at 10 MHz.  But the setup times are 30-40 ns and the clock-out
> are
> > 40-50 ns so doing anything interesting at 10 MHz gets tight.
> >
> >
> >
>
>
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-- 
Best Regards,

James Fournier
I.T. Services
6a Ave. de Lourdes
Pointe-Claire, QC
H9S-4R2

514-562-0645
james at jfits.ca
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