test equipment

[ted01]

What might you recommend for a tube tester and a spectrum analyzer? I'd like a tube tester that actually tells me things like the transconductance of a tube rather than just green=good, red=bad. I'd be using the spectrum analyzer to look at harmonics at the output of each stage of an amp, so it would have to be able to handle tube voltages.

Any thoughts?

Ted

[nickt]

http://members.aol.com/sbench101/#TubeTest

Not built it (yet) but should be much cheaper than a purchased one. There's a Vacume Tube Valley *characterizer* that goes for ~$1300 - probaly more the green good red bad variety (and I'd bet pounds to peanuts based on something like the DIY one)

[CaseyJones]

I'd be using the spectrum analyzer to look at harmonics at the output of each stage of an amp, so it would have to be able to handle tube voltages.

Huh? Why? Why not de-couple the DC and analyze the signal like it's supposed to?

What might you recommend for a tube tester and a spectrum analyzer? I'd like a tube tester that actually tells me things like the transconductance of a tube rather than just green=good, red=bad.

The industry standard would be either the TV-7 or the Hickok 539C, might as well get the "C' version with all the updates. It's the Swiss army knife of tube testers, if that one won't do it it can't be done. Expect to pay over a grand for a nice on that has been calibrated.

[ted01]

Hey Nickt,

Thanks for the reply. I took a look at the schematics in the link, and to be honest, I'm not sure I'm quite ready to build something that complex. I suspect that my odds of pulling that off without setting my house on fire would be slim!

I did a quick search on ebay, and I saw many Hickok testers, some B & K, some Senco, and some military testers (TV-7) and even one of those old drugstore style testers (brought back memories!!). I can't really tell from the pictures if any of them can give me the transcond. and mu. Hopefully someone here has used some of these and can offer a thought.

Ted

[Structo]

http://members.aol.com/sbench101/#TubeTest

Not built it (yet) but should be much cheaper than a purchased one. There's a Vacume Tube Valley *characterizer* that goes for ~$1300 - probaly more the green good red bad variety (and I'd bet pounds to peanuts based on something like the DIY one)

Hmmm, where does the speaker plug in at?

[ted01]

Hey CaseyJones,

I think I understand what you are saying... I'm going to want to look at the AC component de-coupled from the DC plate voltages, so I need to look at the signal AFTER the coupling cap, right? However, isn't it true that at some stages of the amp, that AC component can still swing around plus/minus 60V or so? If so, I'm looking for a spectrum analyzer that can handle that type of input. I'm worried that if I hook up that kind of voltage to my laptop so I can use some of the very cool software analyzers I'll blow the laptop up. If I knew how to build a probe that would be safe to use with a soundcard's input I'd dig that. To your knowledge, does such a thing exist? If not, is there a half decent hardware analyzer that I won't have to offer my first born for?

Ted

[Andy Le Blanc]

I had an O-scope die on me and have had to use a software based spectrum analyser....
you wont blow up you computor
I used a .1 or a .02 cap and either a pot. or resistor attenuator to interface with the sound card
it came with a virtual O-scope and a few other bells and whistles.... the sensitivity of the scope was low...
and the screen was barely read-able
and there was a time latency..... it was usable but had some issues
the spectrum analyser was , on the other hand, awesome.....
and it was free on the web..... look around a bit
Im still waiting to afford a good tester

[skyboltone]

The industry standard would be either the TV-7 or the Hickok 539C, might as well get the "C' version with all the updates. It's the Swiss army knife of tube testers, if that one won't do it it can't be done. Expect to pay over a grand for a nice on that has been calibrated.

Hey Casey, I've been drooling over a TV-7 for years. I think it has alphabetical alternatives as well. What advantage does the Hickok have over the TV-7? Are some of the TV-7 varients better; i.e. the higher the letter the better?

Dan

[ampgeek]

Here is a nice little primer on tube testers that I return to whenever the need/desire arises.

I doesn't directly answer the letter designation vs features question but it definitely has some useable information.

http://www.tone-lizard.com/Tube_Testers.html


Cheers,
Dave O.

[gearhead]

http://members.aol.com/sbench101/#TubeTest

Not built it (yet) but should be much cheaper than a purchased one. There's a Vacume Tube Valley *characterizer* that goes for ~$1300 - probaly more the green good red bad variety (and I'd bet pounds to peanuts based on something like the DIY one)

I bought one a few years ago, when they were way cheaper. Still not chump change.

It does a measurment of gain, indicated on one side of a meter - 1 to 150 or so. 12AX7s should fall in the 100 range. You choose which triode to check with a selector knob. Other side of meter, activated by a push button, tests for balance between the two triodes (for PI matching).

Big plus is it has a build in speaker, so you can check for microphonics via another selector knob. You hear if it squels on its own, or tap it lightly to see how sensitive it is. Saved me countless hours of trying to figure out which preamp tube was causing all the fuss.

[nickt]

http://members.aol.com/sbench101/#TubeTest

Not built it (yet) but should be much cheaper than a purchased one. There's a Vacume Tube Valley *characterizer* that goes for ~$1300 - probaly more the green good red bad variety (and I'd bet pounds to peanuts based on something like the DIY one)

Hmmm, where does the speaker plug in at?

Keep scrolling down the link and there's a tube noise tester with a lineout. Me thinks - bang the tubetester and noisetester together hard enough, cut off the bits that squeeze out round the edges and add a small speaker and driver... simple!

[stokes]

Heres a link to some good info on tube testers www.alltubetesters.com

[benoit]

Tube depot has some old hicocks and heathkits and a few others for sale.