[time-nuts] GPSDO 10MHZ Splitter

[jimlux]

On 6/21/19 7:27 AM, Don Meadows wrote:
> Is there an easy, and cheap way to add a splitter the 10Mhz signal
> from GPSDO, without going to a distribution amplifier to
> feed two different devices?

Just a power divider, or a BNC T, - it's not perfect, but it works.
there's isolation and potential mismatch/reflections, so if you're 
measuring 1E-16 ADEV, maybe not the best approach.

But there's an awful lot of people who just hook up a bunch of test 
equipment with BNC Ts.  Some equipment actually has a switch to 
configure whether the 10MHz input is high Z or 50 ohms.

For "display on the scope" you're going into a high Z input (1 Meg) - so 
the BNC T approach will work fine.

Just be aware that if you pick a coax length that is "wrong" you'll make 
a dandy 10 MHz notch filter. (10 MHz is 30 meters in free space, about 
20 meters in coax, so a 1/4 wavelength is about 5 meters.. )

If you go

GPSDO
cable
BNC T on scope High Z
cable
Counter

Then you don't have problems.

If you go

GPSDO
BNC T - 5 meter cable - Scope High Z
cable
Counter

or
GPSDO
cable
BNC T on counter - 5 meter cable - Scope High Z



> 
> I really don’t want to build a complicated project, or
> spend $200.00 dollars for an 8 output distribution amp
> off the net.  One output would be dedicated for my
>   counter time base, and the other would be an ‘extra’
> 10MHZ source for another counter, or just to display on the scope.
> 
> I don’t have a GPSDO yet, I just can’t decide on one.
> I am leaning to the Trimble, but it’s still undecided.
> 
> Could anyone comment on buying a “Refurbished by Seller”
> GPSDO on E-bay. They are a few dollars cheaper, but I really
> want one I can have trust and confidence in.
> 
> Sorry for the long post.
> Thanks, Don
> 
> 
> 
> Sent from Mail for Windows 10
> 
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