[time-nuts] Spectracom 8140 distribution amplifier and the Taps- some application info

[Bob Camp]

Hi

Based on your data the floor of the taps are a bit lower than I thought. I have only looked at a full system end to end. I was looking at AVAR so the numbers would not compare directly.

Very few people have lab standards that run -120 dbc/Hz at a 1 Hz offset. Even fewer instruments have a floor below that. Looks fine for driving test gear. Not what you might choose for a phase noise standard.

Bob



On Jul 27, 2011, at 7:10 PM, John Ackermann N8UR <jra at febo.com> wrote:

> I'm not sure if there's been other data posted, but a few years ago I did phase noise measurements of the 8140T as well as HP 5087A and TADD-1.  That info is at
> 
> http://www.febo.com/pages/amplifier_phase_noise/
> 
> I got my hands on a tub full of 8140Ts but don't have the 8140 driver. However, all you really need to drive the taps is 10 MHz at ~10 dBm (not sure the exact spec) riding on 12VDC.
> 
> I built a power injector to put 12V on a 10 MHz sine wave tapped off the 10811A output in a 5065A Rb and used that to drive a string of about 10 8140Ts in my old lab.  I terminated the string with a blocking capacitor and 50 ohm load; you need the capacitor to keep the DC off the load.
> 
> As has been pointed out, the 8140T isn't the lowest noise distribution system you can get, but it sure is a convenient way to put a bunch of 10 MHz spigots around the basement and the performance is adequate for anything but the most critical applications.
> 
> John