HP 8410 Network Analyzer

Prior to the HP 8410 microwave device Smith Charts were measured using a slotted line one frequency at a time.  This was a tedious process.  It took me about 1 day to get one Smith chart over a reasonable band of frequencies.  The 415E SWR meter is just an AC voltmeter that has a very narrow filter centered at 1.000 kHz.  Many of the signal generators had a built in 1 kHz modulation to support the use of the "VSWR meter". Also the testing methods for transistors that worked OK at low frequencies like "h" or "z" parameters did not work at higher frequencies because the measurement methods required either an open or short termination on the transistor causing it to break into oscillation.

The 8410 would display the Smith chart in real time allowing tuning.  The 8411 Harmonic Converter has a reference and test input port and inside a variable frequency oscillator generating harmonics way up into the microwave region that acted as the local oscillator to the reference and test mixers.  The down converted Intermediate Frequency was fed back into the 8410 main frame.  The socket for the 8411 umbilical cord could be on the front or optionally n the rear panel of the 8410.  The 8407 is a lower frequency analyzer that covers 100 kHz to 110 Mhz.  There is no separate frequency converter, there are two direct inputs to the 8407.

There was a problem in automated systems because the 8411 might lock onto the harmonic just above the test frequency or just below.  Either one would provide the correct IF frequency.  One way to solve this was to measure the VCO tune voltage going from the 8410 to the 8411.  Another way was to use the 8410C and inject the correct LO frequency from an external synthesizer like the 3335.
4647847  Method and apparatus for eliminating harmonic skip March 3, 1987, 324/76.41; 324/76.43; 324/76.48; 324/76.62; 324/76.82

The 8411 fit on a shelf in the upper left the rear panel. On the upper right of the rear panel there are two APC connectors for the reference line.  If the electrical length of the DUT + the return coax was too long you could add a longer reference line here to balance the phase.
 
 

the 8412 Phase Magnitude Display CRT was one of a number of displays that plugged into the 8410, .  This was the display of choice for looking at gain or loss vs. frequency in real time.
 
 
 

8413 Phase Gain Indicator meter might be useful if you wanted to get more resolution in a manual measurement because you could expand the meter scales.
 
 
 

The 8414 Polar Display CRT is the one that I felt was the most useful.  There were Smith Chart overlays made with a number of different magnifications.  One was the normal Smith chart, one was magnified and the other was a wide angle.  You could also correct for the reflection coupler directivity by using a sliding load. 

Sliding Load

As one person pumped the sliding load back and forth you could adjust the IF attenuation on the 8410 and the X and Y position controls on the 8414 so that the dot was on a big circle centered on the CRT.  If you pressed the zero button after this you would see that the dot was not in the center.  This was a manual way to correct for the directivity of the reflection coupler.  In automated NA systems you just move the sliding load and then the system tests a all the scheduled frequencies, then move it again, etc.

The 8418 Auxiliary Power Supply could be used if you wanted to have two displays like both the 8412 and 8414.  There was an option for the 8414 that grounded both channels just like the zero push button on the front panel.  This allowed the two DVMs to read the "zero" position of the spot.

Early automated systems had a problem in that the A/D converters in the 8412 (I think this is the one but not sure) were not so good.  The fix was to use the 8414 and feed the X and Y outputs to a good digital volt meter.  Older systems used the 59313A 4-channel A/D Converter.

There were a number of test sets all of which had reference and test outputs that matched the reference and test inputs on the 8411.

The 8740 is a DC to 12.4 GHz transmission test set that would be used with the 11605 Flexible Arm that was made up of rotary joints and hard lines.  If you used your own coax to complete the transmission path you might also need to add a longer reference coax line on the back of the transmission test set in order to be able to balance the phase plots (only if you were concerned with phase linearity).
 
 

The 8741 is a 0.1 to 2 GHz Reflection test set and the 8742 is a 2 to 12.4 Ghz Reflection test set.
 
 
 
 

8742  is a 2 to 12.4 Ghz Reflection Test Unit very similar to the 8741 except for frequency coverage.
 
 
 
 

The 8743 is a 2 to 12.4 Ghz Transmission and Reflection test set (Option -018 goes to 18 GHz) but has no provision for reverse S-parameters so you need to physically reverse the device under test to measure them.  In the upper left is the crank to control the electrical length.  Remember that the 8410 is a analog instrument, there is no microcontroller in it.  Microcontroller based network analyzers replaced the mechanical line streacher with math on the phase data.
 

The 8745 S-Parameter Test Set is a 0.1 to 2 GHz S-Parameter test set that can measure all 4 S-Prameters with one insertion of the test device.  This allowed complete testing transistors with a single insertion and without reversing the test fixture.  The transmission return hard line and rotary joint return arm for the 8745 was the 11604.  There also was a rack width DC power supply for biasing transistors that may have been the 8714.

11607A Small Signal Adapter - an external coupler to allow the reference signal to be large and the test signal to be small.  AFAICR Good for testing devices that need a small signal so as not to be driven into non linear operation.  Note: most semiconductors should be driver at -20 dBm or lower.

8746 S-Parameter Test Set covers 0.5-12.4 GHz and has a built in 0 to 70 dB step attenuator (10 dB steps).
 
 
 
 
 

The 11605 is the Flexible Line used to complete the transmission return path, or you can use your own coax cable if phase is not important.  This line is awckward to use because it has limited degrees of freedom.  This line does not have the phase changes associated with many flexible coax lines.
 
 
 
 
 
 
 
 
 

8409 Network Analyzer

This was a computer controlled system based on the 8410.  We rolled our own versions of this system with improvements in the software and calibration methods.

I have read on the internet that the 8409S contained:
8620C based sweeper (although later ones had an 8350 sweeper)
3335A generator - to supply the local oscillator to the 8411 harmonic converter or to drive the Synchronizer???
8709A Synchronizer - to force the microwave generator (operating in single frequency mode) to be on the correct frequency
9845C Calculator with HP-IB interface
2 each 'S' parameter test sets
a switching box that used a single 8411 sampler
the 8410C with the auxiliary display holder
2 or more 6 foot tall rack cabinets

Scalar Analyzers

The 8755, 8756 and 8757 are scalar analyzers that we typically used with the 8350B sweeper.  The 56 & 57 have two HP-IB ports on the back, one to connect to the sweeper and the other to connect to a computer.  Much of the automatic test software that I wrote in HP Rocky Mountain Basic would allow the sweeper to be connected to either the computer directly or to the 56 or 57.  When the sweeper is connected to the 56 or 57 then all commands to it must be passed through the 56 or 57.  When the sweeper is connected directly to the 56 or 57 manual operation of the system is much more user friendly.

These analyzers were a big improvement on using couplers and detectors with an HP 120 (later Tek 5104?) scope and grease pencils to mark the scope face.

Sweepers

Early test setups using the 8410 were driven by octave band HP 690 series sweep oscillators that used Backward Wave Oscillators in plug ins.  To go with each plug in there was a plastic ruler that snapped over the frequency pointers to give you a rough idea of the frequency.  But you would need a wave meter in series with the setup so you could really know the frequency.  The HP BWO sweeper was about 1/3 the size and weight as the Alfred unit that it replaced.  HP had a combiner box that would hold three of the plug ins and a controller plug in that went into the 690 series main frame.  Then the 8690 and 8690B mainframes, 8693A bwo plug-in..  This combination allowed sweeping across a frequency range covered by the three such as 2 to 4 then 4 to 8 then 8 to 12.4 giving a 2 to 12.4 Ghz sweep.  Later the Kruse Stork Model 5000 (later Systron Donner) on highway 101 in Mountain View came out with a small solid state sweeper that could sweep 1 to 18 GHz using a combiner box similar to the HP unit but much smaller and with leveling.
Kruse Stork Patents:
3397365 - 1967, Oscillator with separate voltage controls for narrow and wide tuning -
3377568  - 1968, Voltage Tuned Oscillator
3416100 - 1968, Voltage Tuned oscillator with resistive and capacitive tuning diodes (Varactor and PIN diodes)

Later HP came out with the 8620 then the 8350 sweepers which we used for all kinds of microwave testing.

8620C

Mainframe

Plug-Ins

From the HP-Agilent mailing list:
86222B	0.01-20Ghz	20 mw max.out.
86290B	2.0-18.6 Ghz	10 mw max. out.
86240A	2.0-8.4 Ghz	40 mw  max out.
86240B	2.0-8.4 Ghz	20 mw max. out.
86240C	3.6-8.6 Ghz	40 mw max.out
86251A	7.5-18.6 Ghz	10 mw max. out.
86235A	1.7-4.3 Ghz  	40 mw max. out.
86241A	3.2-6.5 Ghz  	 5 mw max. out.
86242D	5.9-9.0 Ghz 	10 mw max.out.
86245A	5.9-12.4 Ghz 	50 mw max. out.
86250D	8.0-12.4 Ghz 	10 mw max. out.
86260B	10.0-15.5 Ghz 	10 mw max.out
86260A	12.4-18.0Ghz  	10 mw max.out.
86260C	17.0-22.0 Ghz 	10 mw max. out.

From somewhere else:
86220A  0.01 to  1.3 GHz
86222B  0.01 to  2.4 GHz
86230B  1.8  to  4.2 GHz
86235A  1.7  to  4.3 GHz
86240D  5.9  to  9.0 GHz
86241A  3.2  to  6.5 GHz
86245A  5.8  to  6.5 GHZ
86260A 12.4  to 18.0 GHz 10 mW
86290B  2.0  to 18.6 GHz

8350B Mainframe

This was the workhorse at Aertech/TRW Microwave/FEI Microwave for production testing of all kinds of products.  Mostly used with Scalar Network Analyzers but sometimes with 8410 Vector Network Analyzers, like for tuning the RWR modules.

The 8350B has support for mixer testing where two 8350 boxes can sweep with a constant offset (the mixer IF frequency).  This feature was critical for mixer testing and was not supported by otherwise competitive sweepers.

There are HP-IB (IEE 488) commands used for service that are not listed in the user programming manual that are useful for production automated testing.

Plug-Ins - came in suffix letters A/B/C/? and with option numbers for things like a built-in 0 - 70 dB step attenuator.
83522A  0.01 to  2.4 Ghz 20 mW
83525A  0.01 to  8.4 GHz
83540B  2.0  to  8.4 GHz 40 mW
83545A  5.9  to 12.4 GHz
83550A  8.0  to 20.0 GHz
83554A 26.5  to 40.0 GHz
83570A 10.0  to 26.5 GHz
83572C 26.5  to 40.0 GHz
83590A  2.0  to 20.0 GHz
83592C  0.01 to 20.0 GHz
83594A  2.0  to 26.5 GHz
83595A  0.01 to 26.5 GHz
83596A  2.4  to 40.0 GHz
83597A  0.01 to 40.0 GHz
11869A adapter allows use of 86200 series Plug-Ins

There was a problem with automated systems based on the 8350 (and all the earlier signal sources) in that when you programmed the microwave source to go back to some frequency it would be off just a little.  Since an error corrected measurement required measuring a number of standards and then the device under test a number of times, and then combining all the results to remove the errors any change in the frequency would introduce an error.  By using and EIP 575 (as best as I can remember) Source Locking Microwave counter you could program the source and counter to a frequency and the counter would output a DC feedback voltage that could be fed into the 8350 DC coupled FM modulation input to frequency lock the source.  This way you would get the same test frequency every time making the test results more accurate.  Modern network analyzers use a synthesized source so this is no longer an issue.  But the cost for the EIP counter and the 8350 sig gen was much lower than the cost of a synth.

I don't remember trying the EIP + 8350 combination for the mixer spur test system, I think for that application the synth was needed to get the phase noise down low enough.

Power Meters

Patents related to Power Sensors 

Agilent app note AN64-1C has a lot of good information about power measurements including some history.  Alos see Chooosing the right power meter and sensor 5968-7150E.

Bolometers - measure power based on resistance change caused by temperature change from RF heating.
Most accurate non NIST sensor type.

Barretter - A thin wire (might be a 10 mA fuse) is one type of Bolometer with a positive temperature coefficient.
Thermister - semiconductor device with negative temperature coefficient.  By applying DC power to the thermistor when no RF is present and then reducing the DC power to keep the thermister at the same resistance the reduction in DC power allows determining the amount of RF power that's heating the thermister.  There is also another thremister in the sensor to compensate for ambient temperature.  The 478A and 8478B are this type of sensor.

Since NIST will only calibrate Thermister type power sensors (neither Thermocouple nor diode sensors are NIST traceable) the 432A Power Meter is still a current model number because it allows the most precise power measurement.  The related thremister sensors are also current model numbers.

Thermocouple - More sensitive than bolometers and have DC out proportional to RF power in, i.e. square law detection.  Introduced in 1974.  But since there is no longer any DC power substution they need a 50 MHz reference power for operational calibration.  The 8481A is of this type.

Diode - Offer -70 to +20 dBm dynamic range in a single sensor, but the peak power level needs to be below -20 dBm in order to get correct results when measuring complex waveforms.  The -20 to +20 dBm range is good only for CW signals.  To measure non CW singals with average powers in the -20 to +20 range use a thermocouple type sensor.  In order to have the 50 MHz calibration about in the center of the power range a special 30 dB attenuator that's optimized for use at 50 MHz is inserted between the sensor and the 50 MHz cal port.

In 1975 the 8484A diode sensor was introduced.  This was a single Schottky diode that has a small error when the signal has even order harmonic distortion (the + signal is not the same as the - signal and the diode only detects one side).

A newer type based on GaAs material and Molecular Beam Epitaxy (MBE is avery expensive process).  These are the 8481D series sensors and they use two diodes to correct the even order harmonic problem and add a number of benefits related to balance.  Much higher output than the single Schottky diode type because of the improved materials.  The power range is still -70 to +20 dBm.
 

E Series Sensors - These combine the GaAs dual diode sensor with a EEPROM in the sensor to automatically load the cal data into the power meter.

430A/B/C		Tube type
431A/B/C USM-260		Solid State Manual Operation introduces auto temp compensation with 10 kHz ref
432A/B Agilent	.  TM 9-6625-2469-15	Solid State Manual Operation A analog meter B Digital meter no 50 MHz cal reqd old cable Hi Precision (0.2%) Vref & Vcomp out for highet accuracy DC ref
435A/B		Manual operation  single channel 50 MHz cal
436A TS-3793	TM 11-6625-2969-14&P	Single Channel IEEE-488 50 MHz cal new cable
437	Agilent Manual	Single Channel IEEE-488 Sensor cal memory 50 MHz cal new cable
438		Dual Channel  IEEE-488 Sensor cal memory 50 MHz cal new cable

Power Meter Sensors & Cables

Old style, Bolometers

HP 478 & MX-7772/U Bolometer N(m)
10 MHz to 10 GHz
200 Ohms
30 mW max 5 W uS pulse max

. 
8478B N(m)
0.01 to 18 GHz

8478B-11 APC-7
0.01 to 18 GHz

Waveguide Bolometers:
S478A 2.6 to 3.95 GHz
G478A  3.95 to 5.85
J478A  5.3 to 8.2
H478A  7.05 to 10
X478A  8.2 to 12.4
M478A  10 to 15
P478A  12.4 to 18
K478A  18 to 26.5
R478A  26.5 to 40
 

New Style, Thermocouple

Model        FS Power Range  Freq
HP 8481A -20 to +20 dBm  10 Mhz to 18 GHz
HP 8482A -20 to +20 dBm  100 kHz to 4.2 GHz
HP 8483A -20 to +20 dBm  100 kHz to 2 GHz
HP 8481H  0 to + 35 dBm  10 Mhz to 18 GHz
HP 8482H  0 to + 35 dBm  100 kHz to 4.2 GHz
HP 8484A  -60 to -20

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