Pledge: Vacuum Gauge
I have finally received a response from the seller. The gauge has been tested and works. It's an Edwards model D361-46-000. There is no outer housing, as it was installed in larger equipment. The pirani-penning dual use means it will switch to using the penning head when the lower end of the pirani range is reached, stopping the penning gauge from being damaged. It can also trigger external relays and output pressure-data for logging.
Gauge is £59.99 and shipping has been quoted at £12.99. Total would be £72.98.
An alternate gauge was eventually sourced for much less.
To measure very low pressures in the proposed vacuum system, this will connect to both pirani and penning gauges at once. This particular one is by far the cheapest on ebay and has been for months. All others exceed the £100 mark and have been penning-only gauges.
Once we have gauges, planning for the electrical systems can begin fully.
Running Total: £30
Approximate Target: £73