help oldish multimeter

[robert the violinist]

There were no markings on the bulb at all. Is the bulb not anywhere on the schematic ,in my first post?

[Old Sparky]

Since my query in post# 8, I have found several analogue MMs for sale on Amazon,, e-Bay, etc., so plenty of choice if and when i decide to buy a new one.

[Terry]

On a related topic, does anyone make or import a decent analogue multimeter these days?  I have a Russian U4324 which needs a mod. doing in order to fit the nearest available battery,  and a small Di-LOG bought from CPC years ago, but another decent analogue meter wouldn't come amiss.

To quote a well known saying, Google is your friend (other search engines are available).

Having said that, it isn't so easy because so many suppliers leave out what is really the most important thing for the sort of work members of this forum carry out before assessing the ranges and functions covered: the meter's sensitivity.

I wouldn't touch anything with DC sensitivity of less than 20kΩ/V.

There are lots on offer out there costing several hundred pound but I don't expect you to be lavishing so much on your new meter as that!

I came across this (20kΩ/V):



for £25.16 if that interests you?

CPC do a meter at a slightly lower price but don't give the sensitivity. Sometimes you can hover over the picture and read it off the dial but no good here. So I found what appears to be the same meter elsewhere - a mere 2kΩ/V sensitivity, so rubbish for electronic work!

[Terry]

There were no markings on the bulb at all. Is the bulb not anywhere on the schematic ,in my first post?

L1 - at the top? (L = Lamp, rather than the usual inductor.)

Note that it is drawn as if it is a resistor, rather than a bulb.

[ppppenguin]

For an analogue meter there are plenty of secondhand Avos around for reasonable prices.

[Old Sparky]

Terry, you're right of course, but that meter would give readings similar to those published in service data for vintage radios. As you know many of these readings were taken with an AVO7 (1000 OPV)

[ppppenguin]

On the high voltage ranges a DMM may have lower resistance than an analogue meter. Decent DMMs are 10M on all voltage ranges (cheapo ones are sometimes 1M). A Avo 8, 20k per volt, is 20M on the 1000VDC range.

Many of us will use a DMM and make an allowance against the quoted voltage on a circuit diagram. Based on looking at the circuit and experience. So an HT rail will read near enough the same on any meter. But a valve anode with a high value load resistor will give very different answers.

[Terry]

Terry, you're right of course, but that meter would give readings similar to those published in service data for vintage radios.  As you know many of these readings were taken with an AVO7 (1000 OPV)

It depends on how 'vintage' your radios are! The AVO 8 (20kΩ/V) was introduced in 1951 - 68 years ago and, when I started work in 1960, very little of the service data I needed to consult didn't specify that readings were taken using a 20kΩ/V meter!

[Old Sparky]

I was thinking more of pre and immediately post-war radios, on which the measurements would most likely have been made with an AVO7 or similar meters. I don't own anything that old, but over the years have repaired quite a few sets dating from the 50s for other folk. Where I used to work from the 70s to the mid 90s we had both an AVO7 and 8, supplemented later by a Philips DMM and a Fluke 75.

[Mark Hennessy]

A modern multimeter can give the same readings as an AVO 7 or 8 if you have a few resistors handy. For what that's worth...