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Anritsu MS8609A 9kHz - 13.2GHz Spectrum/Signal Analyzer - Short Review

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Wuerstchenhund:
For a while now I felt that I wanted more bandwidth than my trusty R&S FSP 7 could provide, plus I wanted some I/Q analysis capabilities (which the FSP doesn't have), so I went on the search for a 2nd hand SA with a bandwidth of at least 12GHz and decent RF performance. If that new SA came with a less onerous UI then even better.

I didn't need a Tracking Generator as I rather use a wideband noise source (TGs usually come with a hefty premium, and often don't even cover the whole SA bandwidth). I also didn't want something which is 30yrs old, overly large, or which comes with a CRT display. It should be a modern, somewhat compact, low maintenance device.

Capable Agilents (PSA) were way out of my price range. The R&S FSIQ was a contender, but especially the high BW models are expensive, and it comes with the same cumbersome UI as the FSP. So I was contemplating on the alternatives. Advantest had the R3477, but at the time I had been looking asking prices were in the $3k+ range (and it seems they are back there again), and frankly I was never a big fan of some aspects of Advantest's build quality.

I then looked at Anritsu. It's T&M division is pretty much an RF centric company that makes gear which is predominantly used in the telecoms industry. Anritsu kit also has an excellent reputation in terms of reliability and maturity. However, this time I didn't want a simple cell phone tester, so I had a look at Anritu's standalone SAs. After some searching I found a MS8609A Transmitter Tester, a spectrum/signal analyzer sold for testing cell phone tower and other transmitters, with a frequency range of 9kHz to 13.2GHz. All for some $900 (plus shipping and VAT/Customs, but still).

The following is a short review of that MS8609A.


Wuerstchenhund:
Anritsu is a Japanese manufacturer of T&M gear. It was founded in 1895 as Sekisan-sha so it has been around for a very long time. Anritsu pretty much focusses on gear for RF and optical communications, and its main target is the telecoms industry (cell phone service providers).

Anritsu uses a common nomenclature for its test gear, which consists of a prefix (Mx) followed by a four or five digit product number. The 'M' in the prefix stands for Measurement Division, the second letter determines the product category (i.e. 'T'='Test Set', 'S'='Spectrum Analyzers', 'G'='Generators', 'L'='Level meters', 'P'='Photonics').

For someone looking to look at RF spectra, there are two options, MT and MS.

The MT Series contains integrated cell phone test sets of which many of the older ones (i.e. MT8801A, MT8820A) are used by hobbyists as inexpensive Spectrum Analyzer and RF generator. As with many cell phone test sets, the RF performance is pretty limited, which is why the Spectrum Analyzer in these devices is called a 'Spectrum Monitor'.

Anritsu's 'real' lab-grade Spectrum Analyzers carry the 'MS' prefix. 'MS' is also used for derivative products that are based on the standalone SA models, like the MS860xA Transmitter Test Sets which are covered in this short review.

While Anritsu offers test sets under both the 'MT' and 'MS' prefix, as the 'MS' is based on 'true' lab-grade SAs its performance is notably better than the 'MT' Series test sets, by a pretty large margin.

Wuerstchenhund:
The MS8609A Transmitter Test Set is a spectrum/signal analyzer based on the MS268xA Series of standalone Spectrum Analyzers. The MS860xA family has two members, the MS8609A with a bandwidth of 13.2Ghz and the MS8608A with a bandwidth of 7.8GHz.

The MS860xA was introduced in I believe 2004 as Anritsu's alternative to Agilent's E4406A VSA Transmitter Tester, and remained in production until early 2013. However, while the Agilent VSA (which is based on the Agilent PSA Series of Spectrum Analyzers) was a very limited device (max 10Mhz span, 100MHz with W-CDMA/HSDPA option, FFT operation only), the MS860xA retained mostly the same functionality and performance as Anritsu's standalone lab-grade Spectrum Analyzer Series MS268xA. The differences between Transmitter Test Set and Spectrum Analyzer models, aside from frequency range (the MS268xA maxes out at 7.8GHz), are limited to the absence of the Tracking Generator option on the TX Test Set and some front panel connectors (the MS860xA comes with balanced and unbalanced I/Q inputs; the MS8608A also has an additional low power input which is not found on the MS8609A).





Performance Specifications

The baseline specs of the MS8609A are:

- Frequency range: 9kHz to 13.2GHz
- Span: 0Hz, 5kHz to 13.2GHz (+1%)
- RBW: 300Hz to 20MHz (Option 02 Narrow Resolution Bandwidths: 1Hz to 1kHz | option 04 Digital Resolution Bandwidths: 10Hz to 1MHz)
- VBW: 1Hz to 3MHz, off
- Detection modes: Normal, Positive, Negative, Sample, Average, RMS (option 04 Digital Resolution Bandwidths)
- Sweep time: 10ms to 1000s (frequency domain), 1us to 1000s (time domain)
- Sweep refresh rate: >20 traces/s
- No of data points: 501, 1001
- Max input level: +20dBm
- Input attenuator: 0dB - 62dB (2dB steps)
- DANL: -146dBm/Hz (1MHz to 2.5GHz)
- 1dB gain compression: +3dBm (+10dBm typ, >500MHz)
- Level accuracy: +0.75dB (+0.1 to 20dBm), +0.5dB (-49.9 to 0dBm), +1.5dB (-80 to -70dBm)
- Phase noise: <-108dBc/Hz (1Ghz, 10kHz offset), <-120dBc/Hz (1Ghz, 100kHz offset)
- 2nd harmonic distortion: <-60dBc (10-200MHz), <-75dBc (200 to 850MHz), <-70dBc (850MHz to 1.6GHz), <-90dBc (1.6 to 6.6GHz)
- 2-tone TOI distortion: <-85dBc (0.1Ghz to 3.2Ghz)
- Residual response: <-100dBm (1Mhz to 3.2GHz, Band 0), <-90dBm (3.15Ghz to 7.8Ghz, Band 1)

The performance specs for the MS8608A are identical, aside from the lower bandwidth (7.8Ghz instead of 13.2GHz).

It should be remembered that, despite being sold as 'Transmitter Tester', the MS860xA is still a true lab-grade Spectrum Analyzer and not just a test set with tacked-on spectrum monitor functionality, like the MT88xx Series of cell phone testers. It's RF performance is identical to the MS268xA standalone Spectrum Analyzers.


The MS8609A Hardware

The SA is somewhat compact (320mm x 177mm x 411mm) but at approx 16kg it's not exactly a lightweight. The overall construction is rock solid as one would expect from Anritsu.

The front is covered with the typical standard set of buttons.


MS8609A Front Panel

Aside from the RF input (N) there are also balanced and unbalaned I/Q inputs. Unfortunately the input is DC sensitive which means an external DC block should be used to protect the input. The display is a bright 6.5" VGA (640x480) TFT with good viewing angles. The display brightness can be adjusted in the settings, and while it doesn't have a time-out it can be easily switched off by a button located to the left of the display.


MS8609 Display


Below the display is a PCMCIA slot which can take Compact Flash cards via CF-to-PCMCIA adapters to store screenshots (BMP), measurement data and settings. Firmware/software updates can also be performed through it.

I haven't opened my MS8609A yet as it still has the Anritsu seals in place and there was no need to break them, so in the absence of a Service Manual I can't say what platform the system is built on (although it's obviously no PC/Windows platform). My suspicion is that it's based on something like VxWorks on some embedded PowerPC platform. It also does boot pretty fast (7s?).

On the rear there are various connectors for external Reference In/Out, IF Out and Wideband IF Out, Sweep and Video, as well as obligatory GPIB, VGA, Ethernet (Option), serial and parallel connectors.


MS8609A Rear Panel


The instrument is cooled by a large 120mm fan in the back hump which isn't exactly silent, and when the device is in standby then this fan is off but one can hear a another, apparently much smaller standby fan which I guess is used for the Stby PSU. The overall noise isn't excessive but I'd still consider it loud. Unfortunately without having seen the inside it's impossible to check if the noise level can be improved (which I guess it can, as the air the large fan pushes out is barely warm).

Like with many similar instruments, there are several hardware options available for the MS860xA:

- Option 01 - Precision Frequency Reference: Rubidium reference)
- Option 02 - Narrow Resolution Bandwidths (FFT): FFT based narrow resolution RBWs from 1Hz to 1Khz in 1-3 sequence)
- Option 04 - Digital Resolution Bandwidths: RBWs from 10Hz to 1MHz and RMS detector
- Option 08 - Pre-amplifier: switchable pre-amp with 20dB gain
- Option 09 - Ethernet Interface: enables the built-in network port
- Option 30 - LPF for 2GHz Band Carrier Cut
- Option 31 - Low Noise Floor
- Option 32 - Maximum Input Level Extension: extends max input to +30dBm
- Option 33 - High Accuracy Power Measurement
- Option 34 - 4GHz LO Output
- Option 36 - Power Meter Hi Limit Frequency Expansion (6Ghz)
- Option 37 - same as Otion 36 but as retrofit option
- Option 46 - Auto-Power Recovery: disables power switch, on/off performed with stby switch on the rear
- Option 47/48 - Rack Mount

The MS8609A I bought came with options 04, 08, 31 and 47. As I have no use for a rack-mount unit I removed the rack-mount frame and retrofitted the carrying handle, which is missing on rack-mount units.

While some of the options certainly require the installation of additional hardware (i.e. the Rb Reference), others like 02 (Narrow Resolution BW) or 09 (Network interface) shouldn't as the hardware should already be in the instrument. My guess is that these options are just software-locked.


MS8609A Installed/Enabled Hardware Options

Wuerstchenhund:
Software and Operation

The MS8609A offers two operating modes, Spectrum Analyzer ('Spectrum') and Transmitter Tester ('TX Tester'). 'Spectrum' is self-explanatory, and 'TX Tester' contains Modulation Analysis for several modern wireless standards (there's no AM/FM demodulation, though) and Power Measurements. Switching between both modes is done by a simple press of the corresponding front panel button. When switching modes the settings of the exiting mode are memorized so switching to a different mode doesn't let pre-made settings disappear.

Operation of the Spectrum Analyzer is very easy as all functions are either directly available or can be found in the simple menu system. Primary parameters like start/stop frequency, center frequency, span and reference level have their dedicated buttons. In default mode, Attenuator, Sweep Time, RBW and VBW are set automatically in accordance with the frequency span, but each of them can also be set manually.

Setting a marker to the peak signal or setting the peak signal as center frequency can also be done by a single button press. The MS8609A also supports zone markers and multi-marker (up to 10) which can be assigned manually or automatic (by peaks or by harmonics). It also offers various measurements, including Occupied Bandwidth (OBW) or Signal/Noise (in dBc/Hz or dBc/ch).

Screenshots (BMP format), measurement data (CSV format) and settings can be stored on removable storage in the front PCMCIA slot. I'm using a 512MB Compact Flash card in a CF-to-PCMCIA adapter which works fine.



TX Tester and Software Options

In regard to software, since the MS860xA is based on a standalone Spectrum Analyzer, the 'Spectrum' functionality is part of the Core software. However, Anristu offers additional analysis packages for various wireless standards that can be installed, and which can then be found in the 'TX Tester' mode.

The available software options are:

- MX860901B - W-CDMA Measurement Software
- MX860902A - GSM Measurement Software
- MX860903A - cdma Measurement Software
- MX860904A - CDMA2000 1xEV-DO Measurement Software
- MX860905A - Pi/4DQPSK Measurement Software
- MX860920A - BER/BLER Measurement Software (requires MU860920A Demodulation unit)
- MX860930A - Wireless LAN Measurement Software
- MX860950A - HSDPA Measurement Software
- MX860951A - W-CDMA Release5 Uplink Measurement Software
- MX860960A - TD-SCDMA Measurement Software

Each option contains a separate software package that needs to be installed on the instrument (i.e. via CF card and CF-to-PCMCIA adapter). While any number of options can be enabled, the instrument can only hold 3 option packages. If another package is needed then one needs to be erased from the instrument to make space for the new package.




Software packages can't be installed if the coresponding option has not been enabled on the device. How these options get enabled in the first place, I don't know. There are no (end-user visible) facilities to enter product keys.




My MS8609A came with the W-CDMA option. It allows a wide range of measurements, i.e. constellation display, eye diagram, EVM diagram, Phase Error Display, and Magnitude Error Display. For example:





Wuerstchenhund:
I didn't had much time to do a lot with the MS8609A, however here are some simple examples of a few basic measurements.

Here is a simple CW signal from my RF generator connected via a less than perfect wonky BNC cable:




The next example show Phase Noise measurements (C/N0):












The last example shows a simulated 802.11a WiFi signal sourced from an Anritsu MG3700A Vector Signal Generator, in Frequency Domain, Time Domain, and Frequency/Time Domain Split Screen:










This is far from a comprehensive test of course, which would take a lot more time, especially when including the various modulation analysis tools.

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