Tube Testing & Curve Tracing

[JMPGuitars]

I found this one on the internet. Seems good, but I'm not going to verify anything thoroughly.

[roadshow]

Works for me,

Much appreciated!!

[Daviedawg]

Super useful quick ref pages. Thanks.

Dd

[lavrgs]

As a complete newb in the testing world a couple simple questions; I put an EL84 in,

• what are all the sub categories i.e. Derk Pentode etc.
  How long is a basic test
  How do I know if a tube is good or bad?
  how do I see the plots

How do I update firmware - under info it says I'm at V1
I.m getting frequent disconnects

[JMPGuitars]

As a complete newb in the testing world a couple simple questions; I put an EL84 in,

• what are all the sub categories i.e. Derk Pentode etc.
  How long is a basic test
  How do I know if a tube is good or bad?
  how do I see the plots

How do I update firmware - under info it says I'm at V1

If your firmware says V1, then your cal.txt is not setup correctly. Did you use the software from the futracer.com website? Look at the calibration page, it has the basic settings that should be in there: https://futracer.com/curve-tracer/calibration/

Your firmware version is 3.06 probably. It's definitely some version of 3.0x. This is what it looks like in my software:

firmware-version.jpg

If your options says V1, then it thinks it's a different device. FUtracer starts at 2.00 (old versions) or 3.00 (new field upgradable versions).

The "Use It" page tells you more about your other questions: https://futracer.com/curve-tracer/use/

The "sub categories" are modeling options. Modeling is only needed if you want additional information. For example, modeling of a pentode will also give you it's triode curves, Ra, gm, mu, etc.

With or without modeling, you can always show the tube current. I think only the basic current option is available without modeling.

If you only want to know if a tube is good or bad, do a "quick test." The quick tests are generally set with basic information from datasheets, but you should verify, especially if you're using an oddball tube brand or version.

To see the plots, click the Numbered tabs. You can add a ton of tabs if you want. I'll usually add Ra, Mu, Gm, Ia, etc. If it's a pentode I'll show Ia and Is on one plot. If it's a triode, I'll show Ia(a) and Ia(b) on one plot.

There are examples of this on the website. If you feel like I should add some more stuff to the "Use It" page (or any others), let me know what, and I will.


Here's a comparison I made of some subminiature tubes including 5840W vs. 5703 vs. 6S6B tubes:

submini comparison.jpg

Finding which tube has the lowest Ra will also show you which is prone to having higher current. That helped me select the appropriate tube for an M49b tube mic.

The curve is helpful because my target anode voltage was 60V, so that plot (and the data files) gave me good comparison info.


I also attached a set of 7189 tubes I traced, which you can use to compare (and match if that's something you want).

Thanks,
Josh

[lavrgs]

I'm ok on the Version 3.06 . I'm getting a lot of errors that say I need to power cycle I've waited the 60 seconds before hitting start again and I've waited beyond 60 and get
"Unexpected response from tracer; power cycle and restart" maybe bad usb connection? or some other input error>
and now I've had the program exit spontaneously ..twice

[JMPGuitars]

I'm ok on the Version 3.06 . I'm getting a lot of errors that say I need to power cycle I've waited the 60 seconds before hitting start again and I've waited beyond 60 and get
"Unexpected response from tracer; power cycle and restart" maybe bad usb connection? or some other input error>

Email me the cal.txt file from your FUtracer folder in your Windows user folder.

[JMPGuitars]

Your cal.txt file that you sent has only the basic info in it, and doesn't appear to have been connected to your FUtracer yet. You need to go to the debug screen, and select the correct COM port. If you're not sure which COM port, go to Device Manager, and check the list of COM ports there. If you're not sure which one, power cycle the FUtracer and you should see it appear/disappear depending on the tracer's power state.

[lavrgs]

I use COM4 and I have had connection problems. I was thinking that perhaps a bad tube was causing issues; I started with an unknown condition EL84 and had a successful sweep but after a few reties it would not get past the heater stage. I changed to a 12AX7 and after several attempts got it to do a quick sweep.
I was going to try another computer - I'm not sure how the text file gets accessed - maybe it's in the wrong place...? I've been connected several times. I'll head out to the shop in about an hours and maybe we can hook up.

[JMPGuitars]

I use COM4 and I have had connection problems. I was thinking that perhaps a bad tube was causing issues; I started with an unknown condition EL84 and had a successful sweep but after a few reties it would not get past the heater stage. I changed to a 12AX7 and after several attempts got it to do a quick sweep.
I was going to try another computer - I'm not sure how the text file gets accessed - maybe it's in the wrong place...? I've been connected several times. I'll head out to the shop in about an hours and maybe we can hook up.

A bad tube wouldn't cause connection issues. A bad port or bad cable might. If you're using a USB3 port, try as USB2.0 port instead.

[lavrgs]

https://photos.app.goo.gl/SvshteCKuFJQrjrw9 Doesn't look right to me

[JMPGuitars]

It's not right. But when you reinstalled the GUI, you didn't use my premade cal.txt, so Firmware= is the wrong version. The data you showed me is also not calibrated data, but hopefully correcting the Firmware version will show calibrated settings...assuming you calibrated.

[lavrgs]

Don't assume anything...I did try to calibrate prior to todays changes, but when I put the numbers in it wouldn't advance - I'll try again now that the cal.txt file is recognized
There are numbers that show up, do I enter those or do I have to measure?
UPDATE; Now I don't get blank windows...I see some instructions. It doesn't like my -34.74 vdc measured at the -40 test point

[JMPGuitars]

That's pretty low. I typically see around -41VDC at that test point.

[lavrgs]

What's the source of that -40 voltage ?
It seems that voltage regulates to -15 on IC 1...

[JMPGuitars]

IC1 output is -15V, but you should see -40V at the input of IC1. You can follow it back to C1, D1, L1, to T2 (BD138) which then connects to +20V.

Check your board between T2 and IC1 and make sure your connections are clean/solid. Also check and make sure your +20V is good.

[lavrgs]

I think I'm closer, still off on the -40 volts by about 2. I ran a test on the original EL 84 - now the question is how do I save the traces - I expected it to be automatic...UPDATE OK I see 9-)https://photos.app.goo.gl/kR5E473TDdwgndKm6
On a simple test a red value means BAD right?

[JMPGuitars]

I think I'm closer, still off on the -40 volts by about 2. I ran a test on the original EL 84 - now the question is how do I save the traces - I expected it to be automatic...UPDATE OK I see 9-)https://photos.app.goo.gl/kR5E473TDdwgndKm6
On a simple test a red value means BAD right?

On a quick test red value means out of the specified range or margin of error set in the options for that tube.

For 7189 (which I might have copied from EL84):

sweep setup.jpg

Green boxes are what's typical usage in a specific datasheet. The other Bias test points could be set to whatever you want if you want a specific target set.

If you're far enough out of spec, you'll get red in the Readings panel. However, make sure you're properly calibrated before believing anything.

You should also review the datasheets for specific tubes and see how far out you really are.

[lavrgs]

During the calibration I get to hooking up the anode leads and I don't get a chance to enter the number, it sticks on a screen saying to wait for the voltage to stabilize. UPDATE I see that communication to the tester has stopped

[JMPGuitars]

During the calibration I get to hooking up the anode leads and I don't get a chance to enter the number, it sticks on a screen saying to wait for the voltage to stabilize. UPDATE I see that communication to the tester has stopped

Those screens are stepped. Meaning, you don't click next (to begin measuring) until the leads are hooked up. Personally, I power off the FUtracer between making connections, then I wait a moment after powering it back on. The GUI will always try to reconnect to the tracer.

Follow the directions here for calibration: https://futracer.com/curve-tracer/calibration/

Email me if you need me to help you calibrate.

Thanks,
Josh