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HP 8620C SWEEP OSCILLATOR
The HP 8620C Sweep Oscillator is a general purpose Carrier Wave and Sweep Oscillator, which with various RF Plug-In's (see HP 86200 Series RF Plug-Ins for details) operates over the range 10MHz to 18GHz. The 8620C was bought specifically for use with HP 8410C Network Analyser, but is a very useful signal generator on its own. The original cost was $2,650 in 1980. A HP Manual was downloaded from the Web. 
 
Front view with space for RF Plug-In
Rear view
Connections

Front Panel:
Sweep Output BNC socket OV to 10V ramp voltage
For the connections between the 8620C and the RF Plug-In's see HP 8620C Internal Connections.

Rear Panel:
Programming 50 way Amphenol 'Blue' socket.
Switches for: 1kHz Square Wave AM On/Off; RF Blanking On/Off; Display Blanking On/Off.
BNC sockets for: External AM Input; External Trigger Input; Negative Blanking Output; Z-Axis/Marker/Pen Lift Output.

The Programming connector is used to connect the 8620C to the 8410C Network Analyser. For details see HP 8120-2208 Source Control Cable. With Option 001 this adds A6 BCD Programming PCB which allows remote programming from a PC. Option 011 upgrades this to HP-IB programming.

Top view with the covers removed
Bottom view with the covers removed
January 2007

The 8620C was bought in a 'damaged' condition so some repair work is required to get this operational again, for details see Repair HP 8620C Sweep Oscillator. Operator's Checks and Performance Tests need to be completed.

I currently have 2 RF Plug-In's for use with the 8620C: the 86220A  operates from 10MHz to 1.3GHz and the 86260A operates from 12.4Ghz to 18GHz. For details see HP 826220A RF Plug-In or HP 86260A RF Plug-In.


February 2010

I have also acquired a HP 86222A RF Plug-In and a HP 86260B RF Plug-In plus an obsolete 8621A + 86351A. As these model numbers are somewhat confusing, I decided to do some research into the variety of RF Plug-In's that were available. For details see HP 86200 Series RF Plug-Ins.

These RF Plug-Ins also came with 2 more Sweep Oscillators, a 8620C for repair and a 8620A for parts.
 
Job lot of Sweep Oscillators and RF Plug-Ins
Have now completed the repairs and the operator's and performance tests for the original 8620C.

This has taken just over 4 years to complete and is a good example of how long these projects can take.

2nd 8620C Sweep Oscillator
March 2010

Started work on the 2nd 8620C. This was part of a job lot and amazingly is only 7 serial numbers apart from my original unit. Powered up ok and all power supply rails were correct. Operator's Checks have revealed some faults, see Repair HP 8620C Sweep Oscillator for details.

Have now completed the repairs and the operator's and performance tests for the second 8620C.


February 2015

Have bought a HP 86290B RF Plug-In which covers the 2GHz to 18.6GHz frequency range. Testing the 8620C's with a 86290B RF Plug-In showed up a fault with the original 8620C.

2 Microswitches on the left hand side
The 86290B is the only one of my Plug-Ins that needs the band switching output from the 8620C. There are 2 microswitches which operate off a cam behind the band switch, which also changes the scales. The microswitches effectively send a binary code to a logic circuit which converts the code to 4 individual outputs to the RF Plug-In.

The microswitches needed a small mechanical positional adjustment to operate correctly. The parts fitted behind the front panel do have a complex mechanical assembly which need careful handling!

One of the 8620C's is fitted with a HP 86222A RF Plug-In to provide 10MHz to 2.4GHz wide-band, the other 8620C is fitted with a HP 86290B RF Plug-In to provide 2.0GHz to 18.6GHz wide-band.  This gives me a bandwidth from 10MHz to 18.6GHz.

The remaining RF Plug-Ins have all been sold.