Posted by
Clay Autery-2 on
Jun 05, 2018; 8:38pm
URL: http://elecraft.85.s1.nabble.com/K3S-XREF-GPSDO-recommendation-needed-tp7641686p7641725.html
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. :)
>>
>
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