HP 8410 schematic
Owning and Operating the HP 8410 Network
Analyzer
Mark Kahrs, KB2VSQ
9 Everitt Place
Maplewood, NJ 07040A
kahrs@caip.rutgers.edu
http://www.caip.rutgers.edu/kahrs
September 8, 2000
Abstract
The HP 8410 Network Analyzer offersthecheapestand most cost effective solution for network analysis (particularly scattering parameters) above
6 GHz. The paper details the various parts of the 8410 along with the various
trials and tribulations of building an automated 8410 system.
1 Introduction
Kurokawa[1] introduced the generalized scattering parameter (S-parameter) in
1965. S-parameters are extremely useful for all types of microwave circuit design including amplifiers and oscillators[2]. Therefore, when the HP 8410 was
introduced in 1967, it revolutionizedmicrowave design.
It used the new 1430A sampler together with a superheterodyne receiver architecture to produce a calibrated microwavereceiver. Together with the test sets,
it can measure transmission and reflection coefficients for any two port device.
Subsequent offerings from HP (and others) have concentrated on the lower end as
shown in the following table:
As can be seen, the only analyzers that cover above 3 GHz (without internal
doublers) are the 8410, the 8510Aand the 8720. The 8510A/B/C and 8720A are
1
Model Freq. Range(GHz) Std. Source Test set Comments
Test Set
Oscillator
Sweep
Mixer/
Display Unit
8410
MainframeSampler
8407A 0.001-0.110 8601A none Compatible with 8410 plugins
8410ABC .11-18 8620C Many: 874x Needs display plugins
8505A 0.0005-1.3 internal 8503A 8501A normalizer
8510ABC 0.045-26 8341A 851x The gold standard of analyzers
8712ABC 0.0003-3 internal internal production use
8720ABCD 0.045-26 internal internal “Improved” version of 8510A
8753ABCD 0.003-3 internal 85046B,47A option 006 goes to 6 GHz
8754A 0.004-1.3 internal 850xx H26 option goes to 2.6 GHz
Table 1: HP network analyzers
Figure 1: 8410 Block diagram
still out of the reach of all but the most well funded of amateurs. That leaves the
8410.
The paper discusses the various parts of the 8410 as well as the complications
of trying to automate it. Also included is a discussion of the woes of calibration.
2 Principles of operation
Before discussing the various parts and components of the 8410, it will be useful
to see how they fit into the whole scheme. The overall schematic is shown in
Figure 1. Here, the swept signal source introduces an RF signal into the test set.
The RF signal is divided into test and reference signals. The reference signal is
passed directly to the first mixer stage. The test signal goes through the unit under
test and then to the mixer. Most test sets permit the selection of a particular Sparameter set-up by engaging the RF relays inside the set. The 8411A harmonic
converter(shown in Figure 2) contains a sampler for each channel. The mainframe
tries to maintain phase lock between the sampler and the sweep oscillator. It also
downconverts the input to a 278 KHz IF. This is given to the display unit(s).
The inside of the 8411A harmonic converter is shown in Figure 2. The first
2
X
X
SRD
external VCO
From 8410 mainframe
T
R
VCO
Figure 2: 8411A Block diagram
RF mixer (a Grove sampler[3]) is inside the 8411A harmonic converter; a Step
Recovery Diode, driven by a VCO inside the 8411A generates harmonics which
are used to down sample the input signal to 20.278 MHz. The Phase Lock Loop
(PLL) inside the 8410 mainframe tries to maintain lock by controlling the VCO.
The 20.278 Mhz signals are then downconvertedagain by heterodyning with a 20
MHz reference resulting in a 278 KHz IF. This signal is the output signal of the
mainframe to the display units.
3 The 8410 receiver
The 8410 receiver comes in 3 models:A, B and C. The major change occurred
from A to B when many changes were made to the phase lock circuits. The C
model introduces the changes made to “option H17” for the B as well as placing
the 8411A connector on the rear of the instrument. When it comes to trying to
automate the 8410, you must have a B model with the H17 option or the C model.
The H17 option introduces the wiring necessary to provide external injection of
the RF signal for the 8411; this will be explained in the automation section.
4 The 8411A harmonic converter
The 8411A is the most tempermental unit of the 8410 components. The diodes in
the sampler are delicate and sensitive to static. And of course, they are no longer
available. The plug of the 8411A is a unique HP design (shared by the 4815A).
3
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