[pmmunro]

Ian,

I've never seen the printed circuit version as in your Model 9 Mark IV before. The earliest Mk IV meter which I have is dated June 1970 and the Model 8 Mark V was introduced in December 1972, replacing all previous versions of Models 8 and 9.

According to a former production manager at AVO, the Model 8/9 Mark IV was an attempt to reduce production costs, especially assembly times. The MK V versions must have needed a long development time, especially as they were intended to meet NATO specifications from the start, so the Mk IV is likely to have been in production during the Mk V development time. It would seem unlikely that any further development time would have been devoted to the Mk IV once the decision on Mk V development had been taken.

Discounting the possibility that your PCB Mk IV was made by anyone other than AVO, it leaves the possibility that it was an early prototype whose design was rejected in favour of the more conventional and familiar construction.

Any information on your PCB Mk IV's provenance would be of great interest. I wouldn't have thought it could have got out of the factory unofficially if security at Dover was as tight as I have been told it was at Vauxhall Bride Road.

PMM