G&E Bradley Multimeter, Electronic, Type CT471: Battery Details, Anyone?

[russell_w_b]

I was given this electronic test-meter several years ago, complete with a full set of RF probes. Outwardly it is in a rather battered state, but it's quite tidy inside. The battery cover is missing, and it looks to have been fitted with some sort of 12V pack, the only means of contact to the meter being two recessed holes in the underside of the casing, presumably to match up to the battery contacts.

Are battery packs still available, or will I have to modify the arrangement to suit what's currently around? I don't wish to spend shedloads of money on a battery either!

[Top Cap]

Hi Russell, the following link suggests that 3 D size cells are used with an option for an external power pack.

http://www.recelectronics.demon.co.uk/ct471.htm

Les

[wave solder]

There is some info about these meters on this link:-

http://www.richardsradios.co.uk/ct471.html

[batterymaker1]

I found a link to a website showing the unit, but no joy about battery data.

He might be able to give you more info:

http://www.richardsradios.co.uk/ct471.html

[batterymaker1]

LOL!! THREE FOR THREE!!

[russell_w_b]

Thanks for the replies, peeps!

I telephoned Birkett's at Lincoln (should've thought about that in the first place!) and the man there tells me that the meter takes 3 x 'D'-Cells and runs off 4.5V. I got confused into thinking it was 12V. It seems the 'D'-cells fit in a battery pack, which I don't have, so I shall knock something up to suit.

[Brased]

The battery pack is simply a holder for three D cells with two contacts to connect with a pair of contacts within the battery compartment of the instrument - see photos below. It sounds as if these two contacts may also be missing on your CT471C? There's no reason why you shouldn't just use a holder for three series connected D cells, availably cheaply from Rapid and no doubt other suppliers, and hard wire this to the instrument.

It is a useful meter. Good luck with it.

Edward

[russell_w_b]

Originally Posted by Brased

The battery pack is simply a holder for three D cells with two contacts to connect with a pair of contacts within the battery compartment of the instrument - see photos below. It sounds as if these two contacts may also be missing on your CT471C? There's no reason why you shouldn't just use a holder for three series connected D cells, availably cheaply from Rapid and no doubt other suppliers, and hard wire this to the instrument.

It is a useful meter. Good luck with it.

Edward

Well, I've made a start and soldered wires onto the internal spring contacts, leading them out through the holes into the battery chamber. I connected the meter to a PSU set to 4.5V and switched it on. In 'battery test' mode (as per instructions), the needle reaches about 1/3 FSD. It should (I think!) reach past the 'replace battery' mark about 2/3 FSD.

The Ohms won't zero, and the needle vibrates slightly at about 7/8 FSD, as if a small AC component is present. Same on DC volts.

I'm going to have fun with this...!

[Brased]

My battery pack (3 alkaline cells) measures at 4.66V and the 'Check Batt' switch position gives a deflection of 10.4 on the top scale (fsd = 12). Pass is about 7 on this scale.

Edward

[wave solder]

If you are running the meter off of a psu, the oscillation of the needle may be caused by instability due to the leads from the power supply, try putting a 10-47uf capacitor across the battery terminals and see if the needle settles down.