uTracer (Micro Curve Tracer)

[markusw]

My apologies, TTL-234X-5V-AJ is the one I am using now, and it is available from Digi-Key: https://www.digikey.com/product-detail/ ... ND/6823720

The 232R is the first one I used (with Windows . It worked with my Windows 10 upgrade, but as far as I can tell it is not supported for new Windows 10 installations.

Thanks a lot, Martin!

Best regards,
Markus

Sorry, another dumb question:
Rx on the µTracer board goes to Tx on the TTL-234X-5V-AJ audio plug and Tx on the board goes to Rx on the audio plug?
Regards,
Markus

[martin manning]

Rx on the µTracer board goes to Tx on the TTL-234X-5V-AJ audio plug and Tx on the board goes to Rx on the audio plug?

Correct.

[markusw]

Rx on the µTracer board goes to Tx on the TTL-234X-5V-AJ audio plug and Tx on the board goes to Rx on the audio plug?

Correct.

Thanks!!

[markusw]

One more question:
for a 12AX7-type tube, do you wire anode supply to system 1 and screen supply to system 2 or the other way round, in order to have the correct identification in the quick test?
I couldn't find any information on this..
Regards,
Markus

PS: My µTracer is runnig. Will post images once boxing is done.
Just had one major bug: one of the MOSFETs was soldered in the wrong orientation.
I had to clip off the legs to remove it from the PCB. Luckily, I had a bunch of 2SK2545 for replacement.
Didn't notice a difference in performance between the anode supply with the SPA07N60 and the screen supply with the 2SK2545 so far.

[markusw]

One more question:
for a 12AX7-type tube, do you wire anode supply to system 1 and screen supply to system 2 or the other way round, in order to have the correct identification in the quick test?
I couldn't find any information on this..
Regards,
Markus

PS: My µTracer is runnig. Will post images once boxing is done.
Just had one major bug: one of the MOSFETs was soldered in the wrong orientation.
I had to clip off the legs to remove it from the PCB. Luckily, I had a bunch of 2SK2545 for replacement.
Didn't notice a difference in performance between the anode supply with the SPA07N60 and the screen supply with the 2SK2545 so far.

Figured it out myself by comparing Ia and Is in a plot and the quick test
Anode is system 1 and screen system 2.

[markusw]

Almost done with boxing.
I just have one issue:
during operation the negative supply of the µTracer produces a produce a high pitch sound (approximately 10 kHz).
I know is indicated in the construction manual that "During operation the negative power supply can produce a high hissing sound".
Is there a way to circumvent this. It is pretty loud.
The µTracer is working nicely.
Might it nevertheless be that I have a bug in the negative supply?


Markus

[martin manning]

...during operation the negative supply of the µTracer produces a produce a high pitch sound (approximately 10 kHz).
I know is indicated in the construction manual that "During operation the negative power supply can produce a high hissing sound".
Is there a way to circumvent this. It is pretty loud. :shock:
The µTracer is working nicely.
Might it nevertheless be that I have a bug in the negative supply?

In my experience the inductors can generate noise when the boost converters are charging the large capacitors. That may be what you are hearing.

[markusw]

...during operation the negative supply of the µTracer produces a produce a high pitch sound (approximately 10 kHz).
I know is indicated in the construction manual that "During operation the negative power supply can produce a high hissing sound".
Is there a way to circumvent this. It is pretty loud.
The µTracer is working nicely.
Might it nevertheless be that I have a bug in the negative supply?

In my experience the inductors can generate noise when the boost converters are charging the large capacitors. That may be what you are hearing.

Thanks for your support!
It started once I added the negative power supply. Since it is also indicated it the manual I did not worry. I thought that it might disappear once the PCB is completed.
Unfortunately, it didn't. It is a pretty annoying noise.

I checked again. I'm pretty sure now that is only the negative supply.
I can hear a slight change in noise when I turn on the HV supply but the level is pretty low. Too low to worry about.
Also I do not hear the heater supply. Sound does not change when I turn it on.
With heater supply on I measure 19.5 kHz at the heater supply terminals.
At the neg supply I measure 13 kHz.
Do you think that I might have somehow damaged the neg supply inductor? Neg voltage is fine though (-40.9V).

Regards,
Markus

[martin manning]

Seems it's the negative supply inductor then. Some of them are noisy, not sure exactly why. If you are getting correct voltages, I don't think it's anything to worry about.

[markusw]

I works nicely.
I just worry about the noise. It is really annoying
Since the enclosure is vented there is barely any reduction in noise if I put the PCB into the box.
Maybe I will try to replace it. Unfortunately, this is not a fun job.
Guess I will at least need to remove a diode...
Any hints on how to unsolder the inductor with just a plain soldering iron?

[martin manning]

Any hints on how to unsolder the inductor with just a plain soldering iron?

Two regular soldering irons and an extra pair of hands?

[markusw]

Any hints on how to unsolder the inductor with just a plain soldering iron?

Two regular soldering irons and an extra pair of hands?

Good idea!
Thanks!!

[markusw]

In the meantime I've replaced the DR127 inductor of the negative supply.
However, it did not really lower the noise level.
Since replacing the inductor with the same type (DR127) did not help, I decided to go for another type, the DRA127.
At
https://uk.rs-online.com/web/p/wire-wou ... /?sra=pstk
they indicate "Good thermal dispersion with thermal conductive epoxy".
Looking at the bottom of the inductor I have the impression that it is sealed with some black stuff (epoxy?).
Since Ronald mentioned that one of his customers had good success in reducing the noise level by sealing the inductor with epoxy I decided to give the DRA127 a try.

I mounted it as a replacement for the negative supply inductor and started the µTracer.
At first I thought I killed it since there was barely any noise.
Checked the grid voltages: everything perfect!
Although I can not tell that the DRA127 is generally noiseless since I just tested one piece I think it might be worth a try if you want to lower the noise level of your µTracer.

Markus

[dorrisant]

Might have been mentioned here, dunno... Any thoughts on the uTracer 6...?

1000v!!!

[markusw]

Finally I managed to do the labels.
For ECC83-type and 6L6/EL34-type tubes I've hard-wired sockets since these are the tubes I play around with most.
I've added a regulated heater supply that can be switched to 6.3V or 5.67V (90%).
The USB-TTL cable Martin suggested works nicely! Thanks for the tip, Martin!
I've also included Martin's continuous/pulse and calibration switches.

P3070679.JPG

P3070681.JPG

P3070687.JPG

I've started doing test cards for tubes other than ECC83-type or EL34/6L6-type.

P3070696.JPG

It appears I do not have issues with oscillations.

5879 RCA silver plate Tektronix 1 pentode curve Vs 100V.jpg

EL34 RFT 2 curves.jpg

EL95 2 Curve 250V Vs and Vg stepped.jpg

6L6GC-STR Tungsol 1 curve VS 300V 200mA scale.jpg

Lorenz Philips Heerlen 1971 CV492 ECC83 2 curves.jpg

I'm totally amazed by this fantastic device!
Thanks a lot to Ronald for his development work!

Regards,
Markus