Buying High Frequency Spectrum Analyzers on eBay

This is a companion to my guide to buying spectrum analyzers in general.  There is the introductory guide, and a guide for Low Frequency analyzers.  Please note that this doesn't pretend to be an exhaustive list.  It's weighted to laboratory-grade analyzers used for R&D.  There are any number of ancient "klunkers" of the military surplus persuasion on eBay, and they frequently can be bought for $100 or less and coaxed to work.  Even so, I recommend you avoid them; you can recognize them by their having a round, and often yellow or orange screen.

With all the analyzers pictured below, please don't accept my thumbnail descriptions as the last word, or necessarily as being 100% correct in every particular.  Detailed specifications are usually available on the web and you should definitely refer to them before buying!    (As I submitted this to eBay, I was told to remove some pictures, so there are ten analyzers instead of the fifteen I originally included.  Sorry.)

Anritsu MS8604A

Somewhat rarer than the others, and despite its "specialized" function of testing cell phones, this is an excellent analyzer.  Its maximum frequency extends almost to 8GHz in a single range, which is good since many analyzers can't distinguish signals in the GHz range from images and "birdies."  Its main fault is that it doesn't have great sensitivity  which is an unnecessary feature for its primary function.  I really lucked out - I got this for $800 on eBay, with a "defective display" which I was able to replace.  Expect to pay at least $2K for a working one.

HP3588A

This is an early (80's) example of an RF analyzer with digital features.  Although its frequency range maxes out at 150MHz, it can subdivide that range into fractions of a Hz, i.e., with a tiny resolution bandwidth.  It has a tracking generator, and is extremely useful for signal monitoring, especially broadcast.  Look for the oven-oscillator option, and you might also find one that has built-in HP Basic which will allow you to run your own programs on it.  Price typically is $1K to $3K depending on condition.

HP3585A

This battleship is what HP called a "baseband analyzer."  It is a general purpose, lab quality spectrum analyzer with tracking generator.  Because of its limited frequency range - 40MHz - it isn't terribly popular and can be had for a very good price - sometimes under a kilobuck.  This unit has spectacular resolution - a 3Hz filter!  This is the perfect unit for people working with short wave radio equipment. 

HP70000 Series

This is a modular unit and deserves a guide all its own.  I may write one, but not right now!  Without an enormous amount of thought, you could have put together a system with an original price in excess of $100K.  Yet, although the series has only been discontinued in the past few years, you can easily find a system that meets your needs for $3-5K, and if you are patient, many of the individual modules are sold on eBay for a few hundred dollars.  The color mainframe in the picture is usually around $500 if you're keen on getting a system it piece-by-piece.  Different modules give you a frequency range of either 2.9GHz, or up to 26GHz.  There are lightwave modules, narrow- and wide-band IF modules, different quality RF modules, two tracking generators (one is shown next to the display, above), and a number of exotic modules that seem to show up once a year or so.  Be prepared to do some research before buying one of these!  But if you find what you need, the deal can't be beat.  They show up on eBay all the time in different configurations.

HP8559A Plug-In

Here's a very inexpensive way to get a creditable analyzer.  The top half is an ordinary HP oscilloscope display, the HP182T.  Other models can be used here.  Below it is the HP8559A plug in.  It turns the 'scope into a 10MHz to 21GHz spectrum analyzer!  Not as precise or stable as the lab grade instruments, but it has a minimum resolution bandwidth of 10kHz, which is pretty good for the going price of a couple of hundred bucks!  I haven's seen many on eBay recently - there used to be a lot.

HP8568B and HP8566B

This gorgeous hunk of analyzer is the one I coveted for decades, 'til it went from $50K new to $1-3K on eBay.  Lab quality in every respect!  10Hz resolution bandwidth!  0-1.5GHz frequency and a bit beyond.  And best of all?  They are plentiful.  If you get one of these, your spectra will defer to no man.  (Do I sound excited?  Good!)  This is a very popular unit indeed.  If you have critical needs and don't want to worry about the HP70000 system modules, this is the one to get.  The difference between the 8568 and 8566 is frequency coverage:  The 8566 goes to 22GHz, but still maintains the spectacular stability and resolution.  It does not maintain the price, however.  Expect to spend $5 - 9K for one.  Note that the suffix to the model number is important.  An "A" unit will be less expensive, but it has a less advanced computer, which makes it slower and more difficult to remote control.  If you don't plan to use the HPIB (IEEE-488) capability, you can save good money on an "A." 

HP89410A, with RF section (not shown) it becomes an HP89441A

OK, I'm cheating here.  This is such a modern piece of equipment, called a "Vector Signal Analyzer" that you'll have to expect to pay at least $5K for just the baseband unit (shown) or $10K-plus for a complete system that includes the RF section.  Between the two, you can analyze complex signals between almost-DC and 2.7GHz.  I put it here because of its inherent grace, beauty, and style.  I don't think anyone is going to spend that kind of money after just reading a review by me.  (Not that it would be a mistake!)

Takeda-Riken TR4171

For completeness' sake, here is a Japanese high-quality lab analyzer.  It's roughly equivalent to the HP8568B in features and capabilities, but the maximum frequency is only 120MHz.  Fairly rare on eBay, but well under $1K when they show up.

Tektronix 7L5 Spectrum Analyzer plug-in with Option 25 Tracking Generator

Although this unit only has a 5MHz maximum frequency, it functions as a plug-in for the enormously popular and easily-obtained Tek 7603 'scope.  It has the desirable 10Hz resolution and typically goes for well under $500.  Important:  There is a "plug in" input section in the bottom center of the module (surrounded with a black rectangle in the photo).  If this space is empty, don't buy the 7L5 unless you know where to find this module.  They're very scarce, but normally one will come with the analyzer.

Rohde and Schwarz FSA, FSB, and FSC

These are the German answer to the HP8568B and 8566B.  And good answers they are.  R&S is well known for making robust (putting it mildly) equipment.  The three models differ in bottom module - the top display works for all models.  I don't have the specs handy at the moment, but the FSA is about 2GHz, the FSB is about 5.5GHz, and the FSC is 20GHz.  You know how you see labels "two-person lift" or similar?  Remember above where I said "robust."  If you find one of these on eBay, get help carrying it when it comes in!  These are great analyzers and have very useful options such as pre-amps and tracking generators that the HP units lack.  However they don't show up often on eBay, so it probably isn't worth the drool thinking about them.

More Models

I see I've left out IFR, Marconi, and a host of others.  Sorry, there's only so much time and so much room.  I find the spectrum analyzer to be an endlessly useful and fascinating instrument.  But that's me.  You may be more nearly sane.