[Elecraft] K3S XREF GPSDO recommendation needed

[Clay Autery]

Found this in the K3EXREF manual:

"Connect the external 10 MHz signal source to the K3 rear panel REF. 
connector. The 10 MHz source
should have a signal level between +4 dBm and +16 dBm, nominal. For 
square wave sources, 2VDC to
3.3VDC peak is optimum. If the source is a 5V logic level, use a 50-ohm 
resistor in series with the
input. Caution: To avoid damage to the K3EXREF, do not exceed these levels."

So, it would appear that the +8dBm setting I have set as per the VNWA 
directions for 36 MHz, will work in that respect for the K3s.

As I understand it, the Bodnar unit is square-wave, so the only question 
is what is the voltage envelope for the signal?
I STILL am awaiting my crimper to match my cable stock, so I can't make 
a BNC to SMA cable to test the Bodnar output.

The DC voltage on the output from my non-RMS multimeter is about 1.589 
VDC, so that would indicate 2 x 1.589 = 3.178 approx. pk-pk, right?

This agrees with the Bodnar site which says: "Both output signals are at 
3.3V CMOS levels with 50 Ohms characteristic impedance."

Thus, my conclusion would be direct connection via jumper wire only; no 
attenuation, et al. required.

Thanks!  It was easier to research than I thought.  <blush>

______________________
Clay Autery, KY5G
(318) 518-1389

On 06/05/18 14:31, Grant Youngman wrote:
> My Trimble Thunderbolt puts out +7 dBm.  The Bodnar can be set for 
> +13-something down to +7.7 dBm.  Sounds in the ballpark.
>
> The Trimble hasn’t torched anything.  I don’t recall seeing specs on 
> maximum input power for the K3 but I haven't looked at it for a while, 
> have a short memory, and they’re probably there somewhere in the 
> paperwork …
>
>
> Grant NQ5T
> K3 #2091, KX3 #8342
>
>> Can the Bodnar be fed to the K3s directly bu jumper without 
>> attenuation?  Just verifying.  Don't want to feed too high a signal 
>> and torch something.  :)
>>
>