Decca Navigator Valve Voltmeter Mk II Type No 605
 

Morning all,

I think this is a long shot but....

Does anyone have any information on a Decca Navigator Valve Voltmeter Mk II Type No 605. It's a rather splendidly built device recently purchased from eBay.

Re: Decca Navigator Valve Voltmeter Mk II Type No 605
 

I'm afraid I can't help with any information, but it would be good to see some pictures of it, please!
Andy

Re: Decca Navigator Valve Voltmeter Mk II Type No 605
 

I agree,

Back in the 60-70s I worked for Decca Navigator on their HIFIX system and IIRC part of the station set up was a valve-voltmeter, possibly the one you refer to. I've just dug out my HIFIX manual and checked to see if the meter is mentioned but it specifies the Microvac 22B or "any similar valve voltmeter". I think the 22B has a military CT number.

Cheers

Roger/G3VKM

Re: Decca Navigator Valve Voltmeter Mk II Type No 605
 

Here are some pictures.

I think this was built as a small numbers of units as it uses a large number of RS Components parts, and the mechanical build uses drilled holes rather than punched.

The power transformer is not in good shape, but the RM3 lacks the stinkyness one usually associates with a selenium meltdown.

I'm a little way through reverse engineering it, the physical layout drawing is attached.

So I need to repair or renew the transformer and can anyone tell me anything about the resistors?

Re: Decca Navigator Valve Voltmeter Mk II Type No 605
 

I remember those resistors from back in the day when there were 'ordinary' carbon composition types and 'high stability' types, which they are. I built an LCR bridge back in the 60's and ordered high stability resistors where needed, very expensive on pocket-money at the time! (And I never got the bridge working properly).
Andy

Re: Decca Navigator Valve Voltmeter Mk II Type No 605
 

Are they RS Components parts or Radiospares? RSC would date it to the 70s onwards. It was probably a Decca in house unit, they often made dedicated pieces of test gear for their own systems.

Cheers

Roger

Re: Decca Navigator Valve Voltmeter Mk II Type No 605
 

All the relevant components are RS branded, although as I discovered elsewhere on this forum, the rectifier throws back to the earlier Radiospares days.

I'm inclined to agree that this was some kind of "in-house" design and usage so I doubt that I'm going to turn up any documentation anywhere.

I have a question about this kind of instrument: there is a co-ax socket on the front panel labelled "AC Probe". Can anyone suggest what form this probe might have taken? For instance would it have been a simple screened metal pointy thing? Or something more complex with gain and/or attenuation characteristics?

Re: Decca Navigator Valve Voltmeter Mk II Type No 605
 

It would certainly make sense for those blue hi-stability resistors to be Radiospares in origin (who made them, though?). I bought my components in the 60's from Modern Radio in Bolton, and most came from Radiospares.

Andy

Re: Decca Navigator Valve Voltmeter Mk II Type No 605
 

The case is reminiscent of Gaumont Kalee equ1pment - I wonder if there is any connection?