Hi folks,
I'm offering a late production HP 8405A RF Vector Voltmeter in fine operating and cosmetic condition: $275 cash, pick-up only in Menlo Park, CA The 8405A is for cash sale, pick-up only near the intersection of 101 and Marsh Road about half way between San Francisco and San Jose. Sorry, but no exceptions. I have the 8405A posted here with photos: https://forums.qrz.com/index.php?threads/hp-8405a-rf-vector-voltmeter.765676 / Loads more detail available on the web at links listed below. My main use for the 8405A was to measure phase drift between clocks as the frequencies would slowly drift one relative to another. At one point I had a reference 10 MHz clock on the 8405A A channel and up to 7 additional clocks switched onto the B channel. The 8405A gave a DC voltage proportional to the phase difference in degrees. I was using an HP 34970A data acquisition unit with an HP 34905A dual 4:1 RF plug-in module to select one of 7 clock inputs for the B channel. The 34970A chassis includes an internal DVM that I used to measure the DC voltage corresponding to phase difference. All this under computer control. Details on the 8405A can be found in an HP Journal article here: https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1966-05.pdf Operating and Service Manual: http://www.k0to.us/HAM/Articles/HP 8405A Operating and Service Manual.pdf The Agilent HP 8405A Vector voltmeter measures voltage vectors described by both magnitude and phase. This capability makes the Agilent HP 8405A a unique instrument for about any design and test application in the frequency range 1 to 1000 MHz. Features: Measures voltage vectors described by both magnitude and phase Ideal for almost any design and test application in the frequency range of 1 to 1000 MHz Measurement capabilities include insertion loss and group delay of passband-filters and other transmission devices, gain and phase margin of amplifiers, complex impedance of mixers, antennas, etc. Two channels allow for ratio measurements and phase difference between the two channels Gain or loss in excess of 90 dB and phase measurements with 0.1° resolution over a 360° phase range are possible Amplitude of the A and B channels are reading within a dB or so of each other between 1 MHz and 1000 MHz. An image at the QRZ site posting shows the 8405A channel A response compared to an Advantest R3463 spectrum analyzer. I made an attempt to match the cable lengths and losses to the analyzer and 8405A for a fair comparison. The 8405A will include two probe to BNC adapters and two Mini-Circuits 20-dB BNC attenuators as shown in the photos. I've keep these on the probes full time except in very rare cases when I needed direct access to the probe tips. The combination of an adaptor and attenuator does a nice job protecting the probe input circuits. Many thanks for your interest! Bob bobhome <at> pacbell <dot> net
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