[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 
resources.

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.

John
----

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:
> 
>> Hi
>>
>> 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
>> frequency
>> 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.
>>
>> Bob
>>
>>> 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,
>> too.
>>> The difference between 120 and 160 MHz is just a GND wire on pin 6 (vs.
>> open)
>>>
>>> Divide by 10 is left as an exercise.
>>>
>>> regards,
>>> Gerhard
>>>
>>> (But then, some like to build and tune multiplier chains and mixers.)
>>>
>>>
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