I picked up an HP 11710A recently to use as a case for a project I'm working on. I've done this a few times before, as I think buying up an older, fairly obsolete piece of test equipment is a way to get a good enclosure and reuse something which otherwise is not that useful any more.
There's very little information on the 11710A, so I thought I'd post a teardown as I get the enclosure ready for its new life. Feel free to PM me if any of the internal parts you see would be useful. The 11710A uses the same style of case as most HP test equipment of this era, I think they called this System 1.
The white and red squares were added by the previous owner, which looks like it was the Radio Centre of the NZ Navy. Considering its age (build date of around 1978) it's in great shape.
Like most system 1 cases the top, bottom and sides are simply removed, leaving the cast aluminium side panels with the front panel, rear panel and support panel sandwiched in between.
The unit is made up of a few main parts:
- A linear, regulated power supply, starting with an IEC C14 inlet / voltage selector / fuse / line filter assembly, then a transformer, then a regulator PCB with external pass transistor and smoothing capacitor.
- A signal path, with N-type input and output connectors and hardline coax between these connector and a pair of RF relays. The relays seem to be set up so that the signal could either be routed to the downconverter PCB or bypass the unit without modification.
- A downconverter PCB. My understanding is that this mixes the incoming RF with a local oscillator to produce an IF output. I'm not an RF guy.
The power supply regulator PCB and downconverter PCB are shown below:
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