Author Topic: 10 MHz reference signal connections for spectrum analyzer and signal generator ?  (Read 4758 times)

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Offline BravoVTopic starter

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My spectrum analyzer (SA) and my signal generator each has an input for external 10MHz reference signal, and also I have 10MHz from GPSDO.

As my SA does not have the internal tracking generator, I will use the external sig-gen.

All I want is to do is a simple sweep measurement on DUT across the defined frequency range.

How to connect the 10MHz signal source, topology wise, to these two equipments SA and sig-gen ?

FYI, the SA has only single port which can be configured either IN or OUT for the 10MHz signal, while the sig-gen has two separated ports, IN and OUT.

TIA

« Last Edit: April 12, 2019, 08:42:51 am by BravoV »
 

Offline capt bullshot

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You've just suggested the solution:
If your GPSDO has only one output, connect this to Sig Gen ref input, Sig Gen ref output to SA ref input.

Otherwise, of one can (or has), one uses an distribution amplifier for the 10MHz ref.

Edit: for your purpose, most probably you won't need that external reference at all. Let the Sig Gen and the SA run on their internal refs.
« Last Edit: April 12, 2019, 10:12:33 am by capt bullshot »
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Online Mechatrommer

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other than that, a 50 ohm 2-way splitter maybe with equal cable length if synch is required, ymmv.
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline David Hess

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It should not matter how you hook them up as long as the signal levels are appropriate.  Through the signal generator is probably the easiest since it only requires two cables.
 

Offline 0culus

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I guess you might want to also verify that an external reference onto your sig gen also goes out. I would think it should, though, so you can daisy chain.
 

Offline ogden

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Edit: for your purpose, most probably you won't need that external reference at all. Let the Sig Gen and the SA run on their internal refs.

Right. Described measurement do not need *any* frequency accuracy from signal generator. If you trust your SA indication during other measurements, this one is no different, does not require ext.ref.
 

Offline BravoVTopic starter

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Thanks for all replies, really appreciate it.

All noted, my acquired used SA is pretty aged, it seems like the internal xtal is aged and drifted, hence the GPSDO from the 1st place. Also the sig-gen is the new member in my T&M family.

All worked and done, daisy chained from GPSDO -> sig-gen -> SA, and the marker is now spot on.  :-+

I guess the best is to get a 10 MHz distributor isn't it ? Here we go, another TEA adventure begins.  :palm:

Thanks again.  :clap:

Offline Brumby

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I guess the best is to get a 10 MHz distributor isn't it ? Here we go, another TEA adventure begins.  :palm:

That would eliminate any issue with having the connections for daisy chaining.

If you can find an analogue video distribution box with at least 10MHz bandwidth, that should work.
 

Offline BravoVTopic starter

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I guess the best is to get a 10 MHz distributor isn't it ? Here we go, another TEA adventure begins.  :palm:

That would eliminate any issue with having the connections for daisy chaining.

What potential issue/s, if the ref signal is daisy chained ?


If you can find an analogue video distribution box with at least 10MHz bandwidth, that should work.

Yeah, currently in the process looking for it, and also I'm currently considering an offer locally here of an alternative that is an alien unknown GPSDO box that has built-in distributor, worst case if the GPSDO is unworkable (no documentation what so ever on the net), at least I can salvage the distributor part + a nice box + PSU. I've searched and asked around, seems like no one knows it, even the god of GPSDO boards, author of LadyHeather.  :'(

Few shots of the thingy from the seller.

Offline 0culus

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Unless the intermediate members of the daisy chain are also amplifying the external ref signal on it's way out, you'll likely experience losses by the end of the daisy chain.
 

Online Mechatrommer

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I guess the best is to get a 10 MHz distributor isn't it ? Here we go, another TEA adventure begins.  :palm:
at 10MHz its easy to diy. active distributor will need 2 or few cheap gain opamps, the passive one is the said 2-way splitter earlier...
https://support.channelmaster.com/hc/en-us/articles/200383715-How-Much-Signal-Do-I-Lose-Going-Through-A-Splitter-CM-3212HD-CM-3213HD-
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline Shock

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One thread on DIY distribution amps here.
https://www.eevblog.com/forum/testgear/diy-10-mhz-distribution-amplifier-requirements-gathering/

If you are going for an Extron the ADA 6 300MX HV is the high bandwidth model, it has several channels to distribute 10MHz, 1pps, TTL etc and 6 outputs on each means you aren't likely to run out.
« Last Edit: April 13, 2019, 02:05:26 pm by Shock »
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Offline Brumby

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What potential issue/s, if the ref signal is daisy chained ?

For example: 3 units with a 10MHz input and only one has a 10MHz output.   ;D
 

Offline Shock

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What potential issue/s, if the ref signal is daisy chained ?

Any deterioration in a daisy chained signal would have a cumulative effect. Noise, attenuation, effects of each instrument down the line. All things being equal, if you have a distribution amp with six outputs you get six "identical" signals.
Soldering/Rework: Pace ADS200, Pace MBT350
Multimeters: Fluke 189, 87V, 117, 112   >>> WANTED STUFF <<<
Oszilloskopen: Lecroy 9314, Phillips PM3065, Tektronix 2215a, 314
 


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