dBm or dBV Audio Voltmeter

[HollowState]

Originally posted by ECC33

Next question, any recommendations please?
DMMs have got their uses, but I was looking for an analogue meter.

Which meter have you got?

These are the analog meters I would recommend: Hewlett-Packard...

400E or EL (L=log meter movment) good to 10Mhz
400F or FL good to 4Mhz & has a swichable low-pass filter.
400G or GL good to 4Mhz
3400A true RMS good to 10Mhz.
Option 1 on any of these is dB scale on top.

427A multi function AC/DC/volts/current/ohms. (1 Mhz) Battery only.
option 1 gives both AC line operation or battery (22v)

For any of these meters, be sure to get a late version. Stay away from the old blue/gray color and get the mint green/tan color. Especially for the 3400A. The older choppers and thermal couplers inside (3400A only) get flaky with age.

Kikusui and Leader from Japan makes a decent instrument.
Boonton 93A is very good.
Ballantine 323 or 3015A not bad either.
Some of the very old Ballantine 300 series (tubes) were nice meters in their day. They're real cheap now but need restoration.

Victor

[EC8010]

In the UK you may be able to pick up some ex-BBC test equipment such as their EP14/1 (analogue meter), or (if you're really lucky) the old Neutrik analogue test set.

[jackinnj]

Fluke 8920A -- a thermally responding meter like the HP3403C -- they can often be purchased for $20 or so on EBay.

[Conrad Hoffman]

I like the HP400E- very trouble free but not true rms. The HP3400s are also good, true rms, but not nearly as reliable. I don't use either one as much these days, relying on digital bench meters, or the scope. AC analog meters are great for peaking things up or measuring nulls, but the inability to see just what you're measuring is a great weakness. Is it signal, or is it noise? There was also a Heathkit AC voltmeter, very similar to the HP400, that was actually quite good- the IM-5238.

[jackinnj]

Originally posted by Conrad Hoffman
The HP3400s are also good, true rms, but not nearly as reliable.

A dead HP3400 thermopile is about as useful as a dead flashlight battery. HP used to have an "exchange program" for the thermopiles. I wouldn't say they are "unreliable", as much as they can't be abused willy nilly. Precision is limited to a couple digits, unlike an HP3478 or HP34401.

I have an "in-cal" HP function generator and the Fluke 8920A and HP3403C are about equal.

I don't know why prices for the HP3581 wave analyzer have spiked so much -- these have a very good RMS detector and are very acurate to 50kHz -- and will measure down to some tens of nano-volts -- but there's a Genrad model out there as well.

[ECC33]

Thank-you all again, for your help.
Much appreciated

The thing is, I've got a distinct disadvantage to most of you; I'm in the UK; so finding anything remotely useful over here can be either highly unlikely, very expensive, or both!

There is a chap on ebay selling HP3400s for £45. I do like Heathkit stuff, I've got some here, but it's harder to find over here.

Is true-RMS really necessary?

The Fluke 8060a looks like a candidate; according to tubebuilder:-

http://www.tubebuilder.com/testeqreviews.html#fluke8060

After browsing the line-up of the FLUKE meters, I came across the 8060a. This instrument is perfect for making audio measurements. Applications include making direct gain measurement in dB for amplifier stages. It measures the 3dB roll-off points indicating the frequency and voltage at these points. Very high accuracy (0.05% basic). One caution with these meter; do not measure voltage when you are set-up to measure current. Check where your leads are plugged into before use. No real damage occurs, but it is very awkward to replace internal fuses.

Anyone own a Fluke 8060a?

[jackinnj]

There used to be a Heathkit store in London! (I remember from 1967 -- so there's bound to be a bunch of stuff over there.)

Is true-RMS absolutely necessary ? -- not if you are measuring sine waves below a few kHz.