Model 48A Battery - UK Vintage Radio Repair and Restoration Discussion Forum

stickfly · 5th Mar 2023, 1:58 am

Good evening again.
A simple question : I have a model 48A meter that I would like to test.
I know that it takes one battery of 1.5v and I have some AA battery holders that I can use, so can anyone tell me the polarity. I don't want to start by taking the unit apart and the battery compartment has no markings.
I have taken a photo, so which is the +, A or B please.
I just want to see if the resistance range works, I know the DC range works on batteries.
Regards ..... Gary

mickm3for · 5th Mar 2023, 3:27 am

Hi batt type r1662 Eveready so B is + scans of battery case are online if you wanted to make a lookalike , Lots of info at Richards Radios website http://www.richardsradios.co.uk/avometersdata.html Mick

stickfly · 5th Mar 2023, 1:43 pm

Thanks Mick,
I was on that site last night and thought I had it worked out. Just wanted another opinion I suppose

I'll have another look at the 48A later, first I need to take my wife to a garden centre before any more AVO's turn up

Regards ..... Gary

Herald1360 · 6th Mar 2023, 4:46 pm

If you connect a 1.5V cell at random with a series 10k resistor and short the leads together on ohms, watch which way the needle moves. You've a 50% chance of getting it right and if you don't, no harm will result!

stickfly · 15th Mar 2023, 12:28 am

Well I know the polarity now, thanks gents.
Will fit a C size battery holder instead of an AA holder.
Regards ..... Gary

stuarth · 17th Mar 2023, 8:57 am

I would have thought a modern Alkaline AA cell would have an internal resistance at least as good as the original cells, and AA cells are much more readily available, and cheaper, than C cells.

Stuart

Phil G4SPZ · 25th Jun 2023, 9:28 pm

One of my Avos arrived with an (exhausted) R1662 battery inside it. I found that a C-cell fits into the empty R1662 case perfectly.

The extra capacity of a C cell compared with an AA cell might make sense if you intend using the low-ohms range a lot - the 34-range Avometer delivers around 100mA from the test prods on the lowest resistance range.

5th Mar 2023, 1:58 am	#1
stickfly Triode Join Date: Dec 2022 Location: Gravesend, Kent, UK. Posts: 46	Model 48A Battery Good evening again. A simple question : I have a model 48A meter that I would like to test. I know that it takes one battery of 1.5v and I have some AA battery holders that I can use, so can anyone tell me the polarity. I don't want to start by taking the unit apart and the battery compartment has no markings. I have taken a photo, so which is the +, A or B please. I just want to see if the resistance range works, I know the DC range works on batteries. Regards ..... Gary Attached Thumbnails

5th Mar 2023, 3:27 am	#2
mickm3for Heptode Join Date: May 2015 Location: Chatham, Kent, UK. Posts: 964	Re: Model 48A Battery Hi batt type r1662 Eveready so B is + scans of battery case are online if you wanted to make a lookalike , Lots of info at Richards Radios website http://www.richardsradios.co.uk/avometersdata.html Mick Attached Thumbnails

5th Mar 2023, 1:43 pm	#3
stickfly Triode Join Date: Dec 2022 Location: Gravesend, Kent, UK. Posts: 46	Re: Model 48A Battery Thanks Mick, I was on that site last night and thought I had it worked out. Just wanted another opinion I suppose I'll have another look at the 48A later, first I need to take my wife to a garden centre before any more AVO's turn up Regards ..... Gary

6th Mar 2023, 4:46 pm	#4
Herald1360 Dekatron Join Date: Feb 2007 Location: Leominster, Herefordshire, UK. Posts: 16,536	Re: Model 48A Battery If you connect a 1.5V cell at random with a series 10k resistor and short the leads together on ohms, watch which way the needle moves. You've a 50% chance of getting it right and if you don't, no harm will result! __________________ ....__________ ....\|____\|\|__\|__\_____ .=.\| _---\__\|__\|_---_\|. .........O..Chris....O

15th Mar 2023, 12:28 am	#5
stickfly Triode Join Date: Dec 2022 Location: Gravesend, Kent, UK. Posts: 46	Re: Model 48A Battery Well I know the polarity now, thanks gents. Will fit a C size battery holder instead of an AA holder. Regards ..... Gary

17th Mar 2023, 8:57 am	#6
stuarth Heptode Join Date: Feb 2010 Location: Heysham, Lancashire, UK. Posts: 669	Re: Model 48A Battery I would have thought a modern Alkaline AA cell would have an internal resistance at least as good as the original cells, and AA cells are much more readily available, and cheaper, than C cells. Stuart

25th Jun 2023, 9:28 pm	#7
Phil G4SPZ Dekatron Join Date: Apr 2005 Location: Bewdley, Worcestershire, UK. Posts: 4,748	Re: Model 48A Battery One of my Avos arrived with an (exhausted) R1662 battery inside it. I found that a C-cell fits into the empty R1662 case perfectly. The extra capacity of a C cell compared with an AA cell might make sense if you intend using the low-ohms range a lot - the 34-range Avometer delivers around 100mA from the test prods on the lowest resistance range. __________________ Phil Optimist [n]: One who is not in possession of the full facts Last edited by Phil G4SPZ; 25th Jun 2023 at 9:29 pm. Reason: Clarity