Hi
Sure never seen any of them on any gear in my junk pile.
I also never seen a customer ask for them as an output connector on
an oscillator. I wonder how common they actually are.
Bob
On Feb 27, 2010, at 9:59 PM, Bruce Griffiths wrote:
> Actually there are miniature twinax style connectors, for example:
>
http://www.amphenolrf.com/products/twinbnc.asp?N=0&sid=4B8860805409E17F&;
<http://www.amphenolrf.com/products/twinbnc.asp?N=0&sid=4B8860805409E17F&;>
>
> Bruce
>
> Bob Camp wrote:
>> Hi
>>
>> I don't even have the counter and already we're butchering it....
>>
>> The big issue is suitable twin-ax connectors and cable. I have
both, but they are *big*. They never really made it into the world
of miniature connectors and miniature cable.
>>
>> Shielded twisted pair would be another option. That eliminates
the cable as an issue. Small connectors (BNC drop in) are still an
issue though.
>>
>> Bob
>>
>>
>> On Feb 27, 2010, at 9:48 PM, Bruce Griffiths wrote:
>>
>>
>>> Since the input amplifier and trigger circuit are located on a
small daughter board it wouldn't be too difficult to replace this
with an LVDS to CML stage.
>>> The only remaining isue would be what input connector to use
(twinax??, SATA??).
>>>
>>> Bruce
>>>
>>> Bob Camp wrote:
>>>
>>>> Hi
>>>>
>>>> Gee, LVDS what an unusual approach :)....
>>>>
>>>> It would be nice if these instruments had a balanced input.
Common mode noise is indeed an issue in a lot of cases.
>>>>
>>>> Of course wrapping the coax headed to the counter 10X around a
fairly large core can help things a bit.
>>>>
>>>> Bob
>>>>
>>>>
>>>> On Feb 27, 2010, at 9:32 PM, Bruce Griffiths wrote:
>>>>
>>>>
>>>>
>>>>> If one is feeling paranoid about ground loop noise (and
wishes to avoid transformers, optoisolators , or fibre optics), etc
one could always use an LVDS driver with a batter powered(?) LVDS
to CMOS receiver/translator right at the 5370A/B input BNC connector.
>>>>> This may be useful for a DMTD system that uses a 5370A/B.
>>>>>
>>>>> Bruce
>>>>>
>>>>> Bob Camp wrote:
>>>>>
>>>>>
>>>>>> Hi
>>>>>>
>>>>>> AC cmos will easily drive an L pad to match a 50 ohm cable
at these levels. That's true at either 3.3 or at 5.0 volts. There
are a lot of cmos families out there that beat AC for speed and
match the output drive capability.
>>>>>>
>>>>>> Bob
>>>>>>
>>>>>>
>>>>>> On Feb 27, 2010, at 9:12 PM, Bruce Griffiths wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>> 1) One method with 5V CMOS is to add a resistive voltage
divider at the CMOS driver output with a 50 ohm output impedance at
the tap that drives the 5370A/B input.
>>>>>>>
>>>>>>> 2) If one has a 5V 50 ohm driver (eg Thunderbolt PPS
output) use a 50 ohm attenuator at the 5370A/B input.
>>>>>>> For a 5370A an attenuation of at least 11dB is required.
>>>>>>> For a 5370B an attenuation of at least 3dB is required.
>>>>>>>
>>>>>>> 3) One can always use the 10x input attenuation setting
built in to the 5370A/B however this reduces the signal swing to
0.5V at the trigger amplifier input (5V CMOS input).
>>>>>>>
>>>>>>> 4) Attenuate the output of the logic signal by a factor of
2 and use an npn emitter follower to drive the 50 ohm load.
>>>>>>>
>>>>>>> 5) Use 3.3V CMOS signal levels for the 5370B.
>>>>>>>
>>>>>>> 6) Use a current mode emitter or source coupled switch to
drive the 5370A/B input.
>>>>>>>
>>>>>>> The switching jitter of the above drivers will be much
lower than the internal noise of the 5370A/B as long as HCMOS or
faster logic is employed.
>>>>>>>
>>>>>>> Bruce
>>>>>>>
>>>>>>>
>>>>>>> Bob Camp wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> Hi
>>>>>>>>
>>>>>>>> Which *still* carefully avoids the issue of how .....
>>>>>>>>
>>>>>>>> Bob
>>>>>>>>
>>>>>>>>
>>>>>>>> On Feb 27, 2010, at 8:52 PM, Bruce Griffiths wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>> Oops! a small correction (2nd paragraph):
>>>>>>>>>
>>>>>>>>> For the 5370A attenuating the 5V CMOS signal to a 1V
swing with the threshold set to 0.5V is close to optimum.
>>>>>>>>> An input signal with limits of 0V and +1.4V with a
trigger threshold of 0.7V is the maximum usable (for high performance).
>>>>>>>>> An input signal with limits of 0V and +0.3V with a
trigger threshold of 0.15V is the minimum usable (for high performance).
>>>>>>>>>
>>>>>>>>> For the 5370B attenuating the 5V CMOS signal to a 2V
swing with the threshold set to 1V is close to optimum.
>>>>>>>>> An input signal with limits of 0V and +3.5V with a
trigger threshold of 0.7V is the maximum usable (for high performance).
>>>>>>>>> An input signal with limits of 0V and +0.3V with a
trigger threshold of 0.15V is the minimum usable (for high performance).
>>>>>>>>>
>>>>>>>>> Thus using the PPS output (~270 ohm is series with a 5V
74AC04 output) from a Synergy evaluation board that uses an M12M or
M12+ GPS timing receiver to drive the inputs (with a 0-750mV
signal) of a 5370A or 5370B is well within the recommended input
signal range for high performance.
>>>>>>>>> This avoids having to adding an external 5V 50 ohm driver
that some would use.
>>>>>>>>>
>>>>>>>>> Bruce
>>>>>>>>>
>>>>>>>>> Bob Camp wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>> Hi
>>>>>>>>>>
>>>>>>>>>> So exactly how did you know that I bought a (cheap)
5370B a few hours ago on the e-place and was just about to ask
about how best to use it.
>>>>>>>>>>
>>>>>>>>>> Hmmmm.......
>>>>>>>>>>
>>>>>>>>>> Bob
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Feb 27, 2010, at 7:01 PM, Bruce Griffiths wrote:
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>> The attached excerpts from the 5370A and 5370B manuals
indicate that for best performance, that the common practice of
driving the 5370A/B 1x inputs directly from a 5V CMOS logic signal
is a bad idea.
>>>>>>>>>>>
>>>>>>>>>>> For the 5370A attenuating the 5V CMOS signal to a 1V
swing with the threshold set to 0.5V is close to optimum.
>>>>>>>>>>> An input signal with limits of 0V and +1.4V with a
trigger threshold of 0.7V is the maximum usable (for high performance).
>>>>>>>>>>> An input signal with limits of 0V and +0.3V with a
trigger threshold of 0.15V is the minimum usable (for high performance).
>>>>>>>>>>>
>>>>>>>>>>> For the 5370A attenuating the 5V CMOS signal to a 2V
swing with the threshold set to 1V is close to optimum.
>>>>>>>>>>> An input signal with limits of 0V and +3.5V with a
trigger threshold of 0.7V is the maximum usable (for high performance).
>>>>>>>>>>> An input signal with limits of 0V and +0.3V with a
trigger threshold of 0.15V is the minimum usable (for high performance).
>>>>>>>>>>>
>>>>>>>>>>> Bruce
>>>>>>>>>>>
>>>>>>>>>>>
<5370ATriggering.png><5370BTriggering.png>_______________________________________________
>>>>>>>>>>> time-nuts mailing list -- [email protected]
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https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>>>>>>>> and follow the instructions there.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>> _______________________________________________
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>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>> _______________________________________________
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>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
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