[time-nuts] Achieving maximum performance when driving 5370A/B inputs

Bob Camp lists at rtty.us
Sun Feb 28 03:14:38 UTC 2010


Hi

MIght have to move a few things in the shed to fin in an F16.

If they were used in quantity there aught to be cable and connectors out there. The only reason I have the stuff I do is good old IBM and their approach to networking back in the old days. It would be tough to properly drive an R-390 otherwise.

Bob


On Feb 27, 2010, at 10:10 PM, Bruce Griffiths wrote:

> You could look at a surplus F16 (probably wont fit in your garage though) or similar STP was heavily used in MIL STD 1553 avionics buses.
> 
> Bruce
> 
> Bob Camp wrote:
>> 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 -- time-nuts at febo.com
>>>>>>>>>>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>>>>>>>>>> and follow the instructions there.
>>>>>>>>>>>>> 
>>>>>>>>>>>>> 
>>>>>>>>>>>>> 
>>>>>>>>>>>>> 
>>>>>>>>>>>>> 
>>>>>>>>>>>>>                         
>>>>>>>>>>>> _______________________________________________
>>>>>>>>>>>> time-nuts mailing list -- time-nuts at febo.com
>>>>>>>>>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>>>>>>>>> and follow the instructions there.
>>>>>>>>>>>> 
>>>>>>>>>>>> 
>>>>>>>>>>>> 
>>>>>>>>>>>> 
>>>>>>>>>>>> 
>>>>>>>>>>>> 
>>>>>>>>>>>>                       
>>>>>>>>>>> _______________________________________________
>>>>>>>>>>> time-nuts mailing list -- time-nuts at febo.com
>>>>>>>>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>>>>>>>> and follow the instructions there.
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>> 
>>>>>>>>>>>                     
>>>>>>>>>> _______________________________________________
>>>>>>>>>> time-nuts mailing list -- time-nuts at febo.com
>>>>>>>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>>>>>>> and follow the instructions there.
>>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>> 
>>>>>>>>>>                   
>>>>>>>>> _______________________________________________
>>>>>>>>> time-nuts mailing list -- time-nuts at febo.com
>>>>>>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>>>>>> and follow the instructions there.
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>> 
>>>>>>>>>                 
>>>>>>>> _______________________________________________
>>>>>>>> time-nuts mailing list -- time-nuts at febo.com
>>>>>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>>>>> and follow the instructions there.
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>> 
>>>>>>>>               
>>>>>>> _______________________________________________
>>>>>>> time-nuts mailing list -- time-nuts at febo.com
>>>>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>>>> and follow the instructions there.
>>>>>>> 
>>>>>>> 
>>>>>>> 
>>>>>>>             
>>>>>> _______________________________________________
>>>>>> time-nuts mailing list -- time-nuts at febo.com
>>>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>>> and follow the instructions there.
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>>           
>>>>> 
>>>>> _______________________________________________
>>>>> time-nuts mailing list -- time-nuts at febo.com
>>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>>> and follow the instructions there.
>>>>> 
>>>>> 
>>>>>         
>>>> _______________________________________________
>>>> time-nuts mailing list -- time-nuts at febo.com
>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>> and follow the instructions there.
>>>> 
>>>> 
>>>>       
>>> 
>>> 
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>> 
>>>     
>> 
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
>>   
> 
> 
> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 




More information about the time-nuts mailing list