If you go with the 7000 series mainframe, I'd recommend the 7A26 and 7A22 plugins as primary. The 7A26 for frequencies above 1 MHz, and the 7A22 for low amplitude. the 7A22 has sensitivity down to 10uV/div, and switch selectable high pass and low pass filters for various freqs. It's been invaluable to me working with low level audio in a system with lots of high freq digital noise all over.
The 7A13 is great for measuring AC signals accurately or for high freq signals down to 1 mV/div but for audio work, you are generally interested in knowing a voltage within 0.1 db than 0.1% voltage accuracy.
I take the vertical output from the 7000 mainframe into a Hantek digital scope to freeze a signal trace and store to a USB thumb drive for transfer to a computer for documentation. In my application, the Hantek picks up so much digital noise to be worthless viewing even high level signals without filtering through the 7A22 first.
I'd recommend an AN873 DMM, Digital Multimeter. $30 on Amazon, and specs as good as the Fluke 77-V, $372. The two I have were both within the 0.05% spec at 10V and 1V DC. As well as AC and DC volts and current and ohms, it also measures frequency, capacitance, and temperature. The AC voltage measurement is true RMS, but dies rapidly above 2 kHz. Plenty good enough to measure AC or DC volts applied to a scope input to verify scope basic accuracy.
John
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On 5/3/2019 7:39 AM, Harvey White wrote:
On Thu, 2 May 2019 19:59:08 -0400, you wrote:
Harvey, to your point about the application, to be clear, my applications
in order of priority are:
1. tube amp repair.. basically an audio application involving low
frequencies. I occasionally end up in solid state land but have had luck
isolating a misbehaving component with old time techniques.
2. vintage radio repair
So, very basic stuff where the exacting accuracy of the oscilloscope may
not be necessary. But I'd like for them to be the ballpark.
Ballpark you can get without special equipment. DMM calibration is
something else, but there are 10 volt very accurate references
available. It's when you star looking at 4 1/2 digits and up where
things start to get tricky with the reference. That's also just DC
volts, AC, ohms, and current are separate matters.
For what you're looking at, you would like to have a 100 Mhz scope, at
least dual channels. If you're doing audio and you want to start
poking around audio preamps, you'd want a fairly sensitive scope to
match the expected signal levels.
5 mv/div may be too little.
For portable scopes, the 465 would do well. If you want digital as an
add-on (either, without forcing you into digital at all times), then a
468 would work well.
IF you want a 7000 series scope, then a 7603 would do well, 7B53
plugin for sweep, 7A26 (two of them) gives you 4 channels, a pair of
7A18's would give you 75 Mhz bandwidth, which would be good enough,
although I'd go for the 7A26 if you get another scope frame.
You might want to look at the 7A13 (I prefer the electronic readout
one), and the 7A22. Both are differential, have some good low ends for
input ranges, and may be more of what you want for debugging preamps.
almost any 10x probe with a 1meg input match on the plugin would work.
If you care to, the 7704 is a 200 Mhz bandwidth scope, and would work
well with the same plugins.
For specialized test equipment, the SG502 is an ultra low distortion
signal generator module, and the AA501 or AA5001 is a distortion
analyzer. Bear in mind that audio enthusiasts have bid up the prices
on these, because price is no object.
Nice to have, though.
a good 4 1/2 digit meter would help, you'd like the full range of AC,
DC, AC current (could be useful) and DC current.
Harvey
On Thu, May 2, 2019 at 7:27 PM Tony Fleming <czecht@...> wrote:
Sorry for asking this question: What is " levelling head kit" ?
I think it has something to do with calibration....
On Thu, May 2, 2019 at 5:25 PM Craig Sawyers <
c.sawyers@...>
wrote:
And you can get a levelling head kit (no housing) for the SG504 from me
...
David
I have one of your kits and have had for quite a while. Just waiting to
find an SG504 without head
that is less than stupid money ;-)
Craig
