An Awesome External Heater Supply Option

[Big Josh]

Today I added an external heater supply to my uTracer. This is what I used: https://amzn.to/31Iijhs - it was only about $36.

The thing is awesome! It has protection for over voltage/current/wattage, and it has memory settings to recall different setups. With this power supply you can always see the live voltage, current, and power when it’s on (also shows input voltage). It also has a power button to enable or disable the supply.

I've heard of the issues with the uTracer's heater supply, but I didn't realize it was messing up my results. I actually only set this up out of curiosity. I'm glad I did! The tests are much more accurate:

Here's a tube with the uTracer's heater supply:

Here's the same tube with that external supply:

I'm seeing an even bigger difference with pentodes:

Here's an EF806S:

Same tube with the external heater supply:

I also think the thing looks pretty cool installed:

I run my uTracer over bluetooth, and it was annoying before switching between tubes. I would have to restart the GUI every time after hitting Abort, and then sometimes I would have trouble reconnecting bluetooth too quickly. This completely solved that issue. Now I don't do anything to the GUI, and I only turn the heater supply power button on and off between tubes. The GUI has been much more stable this way, and it remembers my last settings in the quicktest when switching between pentodes and triodes. Overall, this is a much better experience.

Thanks,

Josh

[curt]

I use the exact same power supply with my Utracer.  As you said, it works great.  One thing I noted is that mine can be off by a very small amount.  With 6L6s, I have to set it to 6.34V to get exactly 6.3.  This doesn't make a large difference in the readings, but it does affect it a bit.

[VICTOR DASCALESCU]

I use already external PSU but yours is nice and the memories are useful. 

Can it handle more than 3 amps without over warming issues?

As I use to measure lots of 6S33S at 12V/3,5A

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[Boban]

Agree... the external heater supply is very desirable. Here is mine.

Boban

[Josh]

It’s designed to go up to 5 amps, and has a fairly large heatsync on it. If there’s enough air space around it, I don’t see why it would have issues.

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[shlafferty]

Hi Josh, Looks like a very nice implementation. Since there doesn't appear to be pin switching, I guess the sockets address particular tube basings. Just curious: What basings did you pick?

[Big Josh]

Thanks! My tester is setup for. 1: 12ax7 (et al), 2: EF86, 3: EL84, 4: EL34,6L6, etc... That covers 99% of anything I usually care about. Though I did make a goofy socket adapter to test submini tubes with hook clips.

On Mon, Aug 19, 2019 at 6:07 AM shlafferty <st...@tronola.com> wrote:

Hi Josh, Looks like a very nice implementation. Since there doesn't appear to be pin switching, I guess the sockets address particular tube basings. Just curious: What basings did you pick?

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[BHdeC]

Thanks for the info. I bought one too and will report once installed on my tester.

On Saturday, August 17, 2019 at 4:28:41 PM UTC-4, Big Josh wrote:

[BHdeC]

Just a thought: with thi supply we now will be able to plot classic rectifiers such as 5U4, 5Y4, 5R4, etc...

[Martin Manning]

You can, I have done it many times using a bench supply for the heater. However, you must be sure that the heater supply you are using is ground referenced to the uTracer cathode (the unconnected supply must be floating), and be aware that since you are supplying the heater with DC, in tubes with directly heated cathodes the Va-k will vary between zero and Vh, and you have to compensate for that by averaging two runs. Also, rectifier testing requires high current at low voltage, which will drain the uTracer's reservoir capacitors significantly during the measurement. Don't be surprised if the actual test voltage is only 1/2 to 2/3 of the set voltage.

[BHdeC]

Hi guys,

Indeed, that little PS is very cool. I installed it in a new enclosure as my old one was too small.

I also added a heatsink on the back for the toasty LM337. 

I did some quick test and indeed some previously weak tubes now test ok to good. Amazing the impact of the heater PS can do on the tube's performance.

So definitely a must add to the already amazing Utracer.

Thanks again for sharing this device.

Brice.

[Jim Yates]

Glad to see the posting issues are fixed. Thanks!

Can someone please share how the external PS was implemented(wired into the stock circuit)?  

Also, is it necessary to switch between the internal and external or just use the external exclusively? 

Any advice, thoughts and opinions welcomed!

-Jim

[Bill van Dijk]

Hi Jim,

 

You must have missed my earlier post:

 

An external heater supply is not connected to the uTracer circuit at all. Below is a diagram from Ronald’s website explaining some of the heater wiring options:

https://www.dos4ever.com/uTracerlog/tubetester2.html#heater

 

 

 

Bill v

 

 

From: utr...@googlegroups.com [mailto:utr...@googlegroups.com] On Behalf Of Jim Yates
Sent: Thursday, November 25, 2021 9:34 AM
To: uTracer <utr...@googlegroups.com>
Subject: Re: An Awesome External Heater Supply Option

 

Glad to see the posting issues are fixed. Thanks!

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[Jim Yates]

Thanks!

[Big Josh]

The way I did it, only the external supply is used for the heaters. Don't connect the heater supply on the uTracer board to anything. You set your heater voltage (and current limit) on the external PSU, and power it on when you're ready to warm up the tubes. You can double click the GUI to start your test and ignore the heater warmup delay.

Thanks,

Josh

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[Nebojsa Tomic]

One question, do you power that external heater supply from the same PC brick as utracer or do you need separate DC power supply for external heater for measuring DHT tubes?

[Big Josh]

I use the same brick. I have upgraded hardware/firmware now, but I still use the same heater PSU, and only one external power supply.

Thanks,

Josh

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[Bill van Dijk]

It is a personal preference thing to some extent. In my setup I have an external PS with its own power, capable to go to 60V, and more than 5A up to about 30V. If you have big tubes I would definitely recommend a totally external supply since the extra current drawn from the internal power brick that powers the uTracer may have sag under that kind of load which will have a negative effect on the calibration values of the uTracer.

 

Bill v

 

From: utr...@googlegroups.com [mailto:utr...@googlegroups.com] On Behalf Of Nebojsa Tomic
Sent: Saturday, February 05, 2022 7:49 AM
To: uTracer <utr...@googlegroups.com>
Subject: Re: An Awesome External Heater Supply Option

 

One question, do you power that external heater supply from the same PC brick as utracer or do you need separate DC power supply for external heater for measuring DHT tubes?

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[Nebojsa Tomic]

Thank you guys for your reply.

In that case, can I use another 90W brick to power external heater supply?

I ordered this as my external heater supply https://amzn.to/31Iijhs

[Bill van Dijk]

Sure, that should work just fine. Just keep in mind (sorry if I am stating the obvious) you cannot get out more than you put in. Although the meter is capable of a max. 50V – 5A, you will be limited by the power brick you use. With that limitation in mind, you should be fine with that.

 

Just as an FYI, old discarded audio amps are often great sources for higher voltage transformers (30 to 50 Volts is fairly common), and some of them (I like old TV surround units) can deliver a good current also. That option would need a rectifier and filter capacitor also.

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[Ihor Smal]

I am not sure if people who use the same power supply actually test DHTs with it. For testing DHTs the power supply of the heater should be floating so not connected to ground at any other point, because it will be connected via the cathode. So the power supply should be either isolated (but not all Chinese switch mode supplies will do that, if you feed them from the same transformer) or have a separate transformer. Some info about that is in Ronald's logbook but also on ValveWizard's website in the posts of heating the tubes in amplifiers with DC. 

Ihor

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[Hoeberlin]

Ihor, absolutely correct. Cathode is connected to the +19 Volt Rail of the μTracer Power input.

That means, if the Voltage Regulator Module is using the same 19 Volt input, as the μTracer itself, there will be a big Problem with direct heated Tubes.

I definately would recommend to use separate floating Power Supplies, if testing DHT.

Best Regards, Henning

Von der neuen AOL-App für iOS gesendet

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[Stephen Neff]

Hi,  I am ready to put an external heater in my Utracer 3.  Can the internal  heater connections

on the Utracer stay open , that is, not connected.  Will that damage the Utracer?

Thanks,

Stephen

[Martin Manning]

"Can the internal  heater connections on the Utracer stay open , that is, not connected."

Sure, no problem.