Re: Digest for utracer@googlegroups.com - 7 updates in 1 topic

[Okhan Vatansever]

Thank you for all the help. 

I was sure that the output of the DC converter was isolated but I was wrong. Now I need to fit in an external PSU for the DC heaters. Will be a very tight fit. 

Den fre 12 sep. 2025 16:02 <utr...@googlegroups.com> skrev:

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• Problem with heater voltage direct heated triodes - 7 Updates

Problem with heater voltage direct heated triodes

Martin Manning <mman...@fuse.net>: Sep 11 07:05AM -0700 I only have experience with uT 3+, but for directly heated cathodes the filament supply must be isolated. If it is a DC supply, the average filament voltage will be Vf/2, so the test results will not be consistent with the nominal supplied Vf.   A transformer-derived AC supply is another option. If I recall correctly, Ronald devised a circuit to synchronize the measurement pulse with the supply crossing of nominal Vf, but I have had success measuring directly heated rectifiers without that, as seen in the trace below. Presumably, the normal averaging of multiple measurement pulses produces a result very close to nominal Vf. Note the Ia-Va-k trace is relatively smooth, about as smooth as expected when measuring this type of tube using a DC filament supply.   On Thursday, September 11, 2025 at 8:45:10 AM UTC-4 okhan.va...@gmail.com wrote:

Nebojsa Tomic <nesk...@gmail.com>: Sep 11 05:11PM +0200 you will need isolated external power supply check if your AC ground of the external power supply is connected to DC minus (ground)   чет, 11. сеп 2025. у 14:45 Okhan Vatansever

Ihor Smal <iste...@gmail.com>: Sep 11 05:22PM +0200 Indeed you need a fully isolated/floating external heater supply. From the picture it is not clear how you feed that Chinese DC-DC converter, I'd should not have any common grounds with utracer circuit, so it is better to have a separate transformer or power supply to that DC-DC converter. I have exactly the same setup on utracer3 and can test 2a3 tubes without any problems.     On 11 September 2025 14:45:12 Okhan Vatansever <okhan.va...@gmail.com> wrote:

Davo <djda...@gmail.com>: Sep 11 05:43PM +0200 image0.jpeg   Verstuurd vanaf mijn iPhone   Op 11 sep 2025 om 17:23 heeft Ihor Smal <iste...@gmail.com> het volgende geschreven:      Indeed you need a fully isolated/floating external heater supply. From the picture it is not clear how you feed that Chinese DC-DC converter, I'd should not have any common grounds with utracer circuit, so it is better to have a separate transformer or power supply to that DC-DC converter. I have exactly the same setup on utracer3 and can test 2a3 tubes without any problems.   On 11 September 2025 14:45:12 Okhan Vatansever <okhan.va...@gmail.com> wrote:   Hello   I have a external dc heater for my utracer 6 and when testing direct heated triodes the manual says that when using external heater, it is ok to connect the cathode to one of the heater terminals.   The problem I have encountered is that when connecting to one of the heater socket I get about 17V DC instead of 5V. This has unfortunately made me break open 2pcs 300B tube filaments.   If I connect the cathode to the other heater my external DC heater source shuts down.   What am I missing here?   Don't want to blow more 300B or my utracer.   --   You received this message because you are subscribed to the Google Groups "uTracer" group.   To unsubscribe from this group and stop receiving emails from it, send an email to utracer+u...@googlegroups.com.   To view this discussion visit https://groups.google.com/d/msgid/utracer/772ed8f4-b0ca-4b98-9b27-8237c809af4cn%40googlegroups.com.   --   You received this message because you are subscribed to the Google Groups "uTracer" group.   To unsubscribe from this group and stop receiving emails from it, send an email to utracer+u...@googlegroups.com.   To view this discussion visit https://groups.google.com/d/msgid/utracer/199395f5c98.27fb.16a52cc106b662770bf54050d014535e%40gmail.com.

Davo <djda...@gmail.com>: Sep 11 05:45PM +0200 Sorry wrong one lol   image0.jpeg   Op 11 sep 2025 om 17:43 heeft Davo <djda...@gmail.com> het volgende geschreven:      <image0.jpeg>   Verstuurd vanaf mijn iPhone   Op 11 sep 2025 om 17:23 heeft Ihor Smal <iste...@gmail.com> het volgende geschreven:      Indeed you need a fully isolated/floating external heater supply. From the picture it is not clear how you feed that Chinese DC-DC converter, I'd should not have any common grounds with utracer circuit, so it is better to have a separate transformer or power supply to that DC-DC converter. I have exactly the same setup on utracer3 and can test 2a3 tubes without any problems.   On 11 September 2025 14:45:12 Okhan Vatansever <okhan.va...@gmail.com> wrote:   Hello   I have a external dc heater for my utracer 6 and when testing direct heated triodes the manual says that when using external heater, it is ok to connect the cathode to one of the heater terminals.   The problem I have encountered is that when connecting to one of the heater socket I get about 17V DC instead of 5V. This has unfortunately made me break open 2pcs 300B tube filaments.   If I connect the cathode to the other heater my external DC heater source shuts down.   What am I missing here?   Don't want to blow more 300B or my utracer.   --   You received this message because you are subscribed to the Google Groups "uTracer" group.   To unsubscribe from this group and stop receiving emails from it, send an email to utracer+u...@googlegroups.com.   To view this discussion visit https://groups.google.com/d/msgid/utracer/772ed8f4-b0ca-4b98-9b27-8237c809af4cn%40googlegroups.com.   --   You received this message because you are subscribed to the Google Groups "uTracer" group.   To unsubscribe from this group and stop receiving emails from it, send an email to utracer+u...@googlegroups.com.   To view this discussion visit https://groups.google.com/d/msgid/utracer/199395f5c98.27fb.16a52cc106b662770bf54050d014535e%40gmail.com.

Davo <djda...@gmail.com>: Sep 11 05:48PM +0200 image0.jpeg   Verstuurd vanaf mijn iPhone   Op 11 sep 2025 om 17:45 heeft Davo <djda...@gmail.com> het volgende geschreven:    Sorry wrong one lol   <image0.jpeg>   Op 11 sep 2025 om 17:43 heeft Davo <djda...@gmail.com> het volgende geschreven:      <image0.jpeg>   Verstuurd vanaf mijn iPhone   Op 11 sep 2025 om 17:23 heeft Ihor Smal <iste...@gmail.com> het volgende geschreven:      Indeed you need a fully isolated/floating external heater supply. From the picture it is not clear how you feed that Chinese DC-DC converter, I'd should not have any common grounds with utracer circuit, so it is better to have a separate transformer or power supply to that DC-DC converter. I have exactly the same setup on utracer3 and can test 2a3 tubes without any problems.   On 11 September 2025 14:45:12 Okhan Vatansever <okhan.va...@gmail.com> wrote:   Hello   I have a external dc heater for my utracer 6 and when testing direct heated triodes the manual says that when using external heater, it is ok to connect the cathode to one of the heater terminals.   The problem I have encountered is that when connecting to one of the heater socket I get about 17V DC instead of 5V. This has unfortunately made me break open 2pcs 300B tube filaments.   If I connect the cathode to the other heater my external DC heater source shuts down.   What am I missing here?   Don't want to blow more 300B or my utracer.   --   You received this message because you are subscribed to the Google Groups "uTracer" group.   To unsubscribe from this group and stop receiving emails from it, send an email to utracer+u...@googlegroups.com.   To view this discussion visit https://groups.google.com/d/msgid/utracer/772ed8f4-b0ca-4b98-9b27-8237c809af4cn%40googlegroups.com.   --   You received this message because you are subscribed to the Google Groups "uTracer" group.   To unsubscribe from this group and stop receiving emails from it, send an email to utracer+u...@googlegroups.com.   To view this discussion visit https://groups.google.com/d/msgid/utracer/199395f5c98.27fb.16a52cc106b662770bf54050d014535e%40gmail.com.

David Hanslip <hans...@gmail.com>: Sep 12 09:09AM +0800 I use a Chinese supply too. I power it from a 19V laptop power pack. No earth.   On 11 Sep 2025, at 11:48 pm, Davo <djda...@gmail.com> wrote:      <image0.jpeg>   Verstuurd vanaf mijn iPhone   Op 11 sep 2025 om 17:45 heeft Davo <djda...@gmail.com> het volgende geschreven:    Sorry wrong one lol   <image0.jpeg>   Op 11 sep 2025 om 17:43 heeft Davo <djda...@gmail.com> het volgende geschreven:      <image0.jpeg>   Verstuurd vanaf mijn iPhone   Op 11 sep 2025 om 17:23 heeft Ihor Smal <iste...@gmail.com> het volgende geschreven:      Indeed you need a fully isolated/floating external heater supply. From the picture it is not clear how you feed that Chinese DC-DC converter, I'd should not have any common grounds with utracer circuit, so it is better to have a separate transformer or power supply to that DC-DC converter. I have exactly the same setup on utracer3 and can test 2a3 tubes without any problems.   On 11 September 2025 14:45:12 Okhan Vatansever <okhan.va...@gmail.com> wrote:   Hello   I have a external dc heater for my utracer 6 and when testing direct heated triodes the manual says that when using external heater, it is ok to connect the cathode to one of the heater terminals.   The problem I have encountered is that when connecting to one of the heater socket I get about 17V DC instead of 5V. This has unfortunately made me break open 2pcs 300B tube filaments.   If I connect the cathode to the other heater my external DC heater source shuts down.   What am I missing here?   Don't want to blow more 300B or my utracer.   --   You received this message because you are subscribed to the Google Groups "uTracer" group.   To unsubscribe from this group and stop receiving emails from it, send an email to utracer+u...@googlegroups.com.   To view this discussion visit https://groups.google.com/d/msgid/utracer/772ed8f4-b0ca-4b98-9b27-8237c809af4cn%40googlegroups.com.   --   You received this message because you are subscribed to the Google Groups "uTracer" group.   To unsubscribe from this group and stop receiving emails from it, send an email to utracer+u...@googlegroups.com.   To view this discussion visit https://groups.google.com/d/msgid/utracer/199395f5c98.27fb.16a52cc106b662770bf54050d014535e%40gmail.com.   --   You received this message because you are subscribed to the Google Groups "uTracer" group.   To unsubscribe from this group and stop receiving emails from it, send an email to utracer+u...@googlegroups.com.   To view this discussion visit https://groups.google.com/d/msgid/utracer/BB52299E-8B33-4EF2-A93E-3CF62E1FDC6D%40gmail.com.

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[Davo]

You can add an isolator module or transformer also you want to use 1 PSU 

Verstuurd vanaf mijn iPhone

Op 12 sep 2025 om 16:29 heeft Okhan Vatansever <okhan.va...@gmail.com> het volgende geschreven:



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