[time-nuts] Secondary phase noise standard & FE405

Gerhard Hoffmann dk4xp at arcor.de
Sat Nov 12 16:24:29 EST 2016

I have made an experimental secondary phase noise standard, as F.Walls

would call it. In the end, it's inspired by his paper.

There is not much to it. There is a Mini Circuits PSC2-1 splitter that is

fed from an oscillator or other source. The splitter divides it into a

clean output that goes to another SMA.

The other half is to be dirtyfied. It is fed into another PSC2-1 that is

used as a combiner. Its output goes to the signal source analyzer via

a third SMA.

The dirt input is either  a 4th SMA or a noise generator. That is switched

by reed relays. The noise generator consists of a 60 Ohm resistor and

currently 2 LMH6702 stages for +20 and +40 dB. I'm not sure if the

60R really defines the level, but the gain is at least flat from AF

to > 100 MHz. If not yet, it can be made so. I have already a

solid step attenuator so I can get rid of those reed relays.

I checked it this evening with my FE405 osc I bought earlier this year

and that has enjoyed a good month of continuous running by now.

I observed

1. that the FEI delivers only 3.5 dBm

2. that there are lots of birdies far out.     Is that normal, maybe 
from the DDS?

The addition of the noise reference lines seems to work properly.



low calibration line:


high calibration line:


Later this evening I'll add the pic of the tin box. I need a USB cable...

:-)  Gerhard

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