[time-nuts] 10 MHz -> 16 MHz
John Ackermann N8UR
jra at febo.com
Tue Oct 9 15:31:36 EDT 2018
Hi Pete --
TAPR did one production run of the ClockBlock at the beginning of 2007,
building 100 units, and they were available until all were sold (which
IIRC took a couple of years). I'm not sure if we ever looked at doing a
second run, but I seem to remember that one of the components became
either obsolete or crazy expensive.
But this is a good chance to describe how TAPR handles product
manufacture. We think of ourselves mainly as an R&D organization making
stuff that's not available elsewhere. We're a volunteer, non-profit,
group and the up-front cost to get a bunch of boards assembled is a
major hit to our bank account. We can't afford to build units that will
sit in inventory for years. (This discussion is mainly about assembled
products; the sunk cost for kits is usually much lower.)
So, our usual approach is to do one manufacturing run of a quantity we
are pretty sure will sell out quickly. It's usually not cost-effective
to build less than 50 units, and the per-unit cost drops dramatically as
you increase to 100 or 200 pieces. We do our best to balance unit cost,
upfront cost, and expected sales in a way that's prudent based on our
We normally don't expect to do a second manufacturing run, as the first
run usually consumes most of the demand. If we place a second order for
a smaller quantity, the unit cost goes up and we would have to increase
price accordingly. If we do a larger order, we risk turning our limited
cash into aging inventory.
There are some cases where the demand justified a second run -- for
example the TICC, where virtually all the units were pre-sold and we
felt comfortable getting a second batch. But our niche market is small
enough that in most cases one run is enough to saturate it.
I believe we have some bare ClockBlock PCBs available; if you're
interested in rolling your own unit, contact me off-line and I'll see
what we can do.
On 10/09/2018 01:25 PM, Pete Lancashire wrote:
> I just wish the tapr would not discontinue things so fast it seems once you
> see it mentioned it's discontinued
> On Sun, Sep 30, 2018, 1:08 PM Bob kb8tq <kb8tq at n1k.org> wrote:
>> If (as originally specified) noise and jitter are not a big deal - there
>> are a lot
>> of chips out there like the ICS570. They are designed to do weird ratio
>> conversions so 10 to 12 or 10 to 16 are trivial for them. The Clockblock
>> board was
>> one way to get it all put together.
>>> On Sep 30, 2018, at 12:05 PM, Gerhard Hoffmann <dk4xp at arcor.de> wrote:
>>> Am 30.09.2018 um 16:49 schrieb Attila Kinali:
>>>> The simplest way I can think of is the following:
>>>> Use a 74LV8154 to divide the 10MHz down to 152.587890625Hz.
>>>> Use the capture timer unit of the uC to measure the phase of the
>>>> pulse. Use any kind of DAC (internal, external, PWM,...) to steer
>>>> the 16MHz VCO. Depending on how fast the timer unit runs, this
>>>> will give you something in the order of 10-200ns dead-band.
>>>> By choosing the right frequency for the timer unit, one can
>>>> get it to "dither" a bit and then use averaging.
>>>> For lower jitter, use one half of a Nutt interpolator
>>>> to get the timing difference between the 152Hz signal
>>>> and the 16MHz (ie similar to what the SRS FS740 does).
>>>> Use something akin Nick Sayer's time-to-amplitude converter
>>>> for the fine measurement.
>>>> Same works equally well for 12MHz.
>>> Wow. That's truly a Rube Goldberg design.
>>> There is a simpler way. IDT ICS570. Digikey 800-1073-5-ND
>>> Solder time less than 10 minutes.
>>> I had the 3V3-Version in the parts drawers, officially it takes the 5V
>>> version to generate the 160 MHz, but the 3V3 version happened to work,
>>> The difference between 120 and 160 MHz is just a GND wire on pin 6 (vs.
>>> Divide by 10 is left as an exercise.
>>> (But then, some like to build and tune multiplier chains and mixers.)
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