Hi

The Symmetricom Time Pod is pretty much the lowest cost commercial / newl “low phase noise” measurement instrument. You can find all sorts
of older stuff on auction sites in who knows what shape. The HP 3048 is the granddaddy of them all.

Bob

It appears that Leo's using a notch filter to remove the carrier before measuring it with the E4406A, so it's not quite a plug-and-play sort of measurement.  But yes, the E4406A is a really cool piece of gear given the prices they sell for.  It's not meant to be a general-purpose spectrum analyzer -- and Agilent went well out of their way to make sure of that -- but it can still handle many common SA measurement tasks including SSB noise.

The plot on that page came from my freeware phase noise app from http://www.ke5fx.com/gpib/pn.htm , which is a (very) distant ancestor of TimeLab.  The last two FAQ entries at http://www.ke5fx.com/gpib/faq.htm offer some hints for suppressed-carrier measurements that can be used with the E4406A and other analyzers.  There's nothing special about the E4406A with respect to this type of measurement, except that it's an unusually cost-effective way to get the job done.

I've also heard of people opening up the E4406A and feeding HF signals directly to the ADC, eliminating the LO noise contribution but not the ADC's white noise, 1/f noise, or clock jitter.

The E5052A/B's most immediate predecessor was probably the HP 4352A/B.  They were made specifically for VCO and PLL transient analysis and noise measurement, and they've been selling in the $1K-$3K neighborhood for several years.  Their measurement floor is better than a conventional spectrum analyzer, but still not adequate for "time nuts"-class measurements on 10 MHz sources.

-- john, KE5FX
Miles Design LLC

On 18 June 2016 at 21:01, John Miles john@miles.io wrote:

Thank you. In which case it may or may not be better than  the HP 70000
series SA I have, consisting of:

• 70004A display,
• 70905A 50 kHz to 22 RF GHz front end
• 70902A (10 Hz to 300 kHz) IF
• 70903A (100 kHz to 3 MHz) IF
• 70310A precision frequency reference.

• some irrelevant bits.

I was not looking for a general purchase SA, as I have one of them already.

I note your software works with the HP 70000 too. As I say, I already have
one of them, but was thinking the E4406A would be a worthwhile addition.
But perhaps not in that case. Although maybe it will outperform my 70000
system for phase noise measurements. I expect you will know the answer to
that.

BTW, the link to the  "Wenzel Associates, BluePhase 1000 Phase Noise Test
System Operations Manual
http://www.wenzel.com/pdffiles1/BP1000Manual/BP_1000_v101_2_.pdf (30
pages, 1.3 MB)" PDF is broken.

It seems the HP 4352Bs are available for a little under $1000 now, but are
but still twice the price of a E4406A.

neighborhood for several years.  Their measurement floor is better than a

OK, I will give this idea a miss. I was actually looking to compare 116 MHz
oscillators. but I guess the same principles apply.

Cheers John.

Dave, G8WRB

On 6/18/16 12:05 PM, Bob Camp wrote:

the time pod is about 8-9k (I just got a quote on one).

I don't think the 4406 is inherently very quiet, if they're making close
in measurements, they may have another quiet source to drive it from, or
they are beating the unit under test against a quiet reference, and just
using the 4406 to look at the IF.

HI

It sort of depends on what offset frequency you are looking at. If you are after very wide band stuff at very low levels,
the notch filter / spectrum analyzer approach has always been a good one. You may or may not need a low noise
amp after the notch depending on the analyzer. Your notch may need to be more deep with some analyzers. It’s
been used since at least the 1960’s. I would not be surprised to find it goes back a bit further than that.

One basic assumption with the notch approach:

You are measuring total noise. Both the AM noise and PM noise go past the notch and into the analyzer. The fundamental
assumption is that out there the noise is equally distributed between AM and PM. There would be a paper in it if you
can prove that’s not the case.

Lots of fun !!

Bob

The E4406A will let you measure all the way down to 1 Hz from the carrier, and is quieter past 100 kHz.  And it's faster, being FFT-based.  Overall, though, their LO noise floors aren't that different.  They both need a lot of help to perform serious PN measurements.

Thanks -- coincidentally, someone else just reported that one a few days ago.  I've fixed it but haven't updated it on the server yet.  It's safe to say there are plenty of other broken links on my site, as some of those pages are over 10 years old now.

Sadly, there are few good answers there other than "build a quadrature PLL."

-- john, KE5FX
Miles Design LLC