Advance VM77 Valve Millivoltmeters

[Skywave]

Al,
I've attached the 'B' Manual which has a better description of the Amplifier etc and how to calibrate it.
Alan

So I see: thanks. Having read it through, most of same vagueness and apparent inconsistencies remain. Plus I found these:

Quote 1:
When the amplifier jack is inserted, [this being the output of the amplifier], the meter function is inaccurate: the jack plug must be removed for use as a voltmeter.
Unquote.

Quote 2:
The amplifier output, in r.m.s. volts, with 100 kΩ, 40 pF load, is within 2 dB of meter on top scale, at half scale This holds on all range settings.
Unquote.

So on that basis, the "within 2 dB of the meter top scale . . ." {quote 2} is an inaccurate indication. {quote 1}.
Elsewhere in the spec. write-up, implications are given that 2 dB indications are 'accurate'.
Huh?

Plus when they say "within 2 dB of meter on top scale, at half scale", do they really mean "within 2 dB of meter on top range {of meter}, at half scale" ?

If I was working for Advance as a technician, I would want to re-write that entire spec. so that it was a good deal 'tighter' and more consistent.

Now some might claim that I am now becoming a bit of a pedant and possibly hair-splitting - but, (of course), I would disagree with that. And that is simply because I have spent many hours writing test procedures for electronic equipment, using those procedures - and using those written by others. And it was my name that appeared on the 'Tested (to spec.)' sheet that was issued with the item to the customer - who, more often than not, were highly-trained, qualified and experienced engineers and technicians. And should that item fail its Goods Inwards test at their establishment, guess who would get a rocket? Correct!

I know all this sounds a bit negative, and I do indeed try to avoid undue criticism - when it is clearly unwarranted, but for reasons I have previously explained, I place great store in having T & M kit that you can trust and rely on. Would you be happy with a 12" ruler that now and again reported that a certain length was "somewhere between 11.5 and 12.5 inches"?

Al.