shortly I start this thread:
https://www.diyaudio.com/community/...-on-variants-which-one-is-most-useful.403470/
Delayed anode voltage after switch on is one step for extending service life of several others - that's what I thought until now, because commercial products also sometimes incorporate this delay for anode voltage.
OTOH - I have not been able to find any descriptions of investigations as to whether it makes a difference to the life expectancy of tubes if the high voltage is switched on with a delay or not.
Rod Elliott mention the same - OTOH he observed a longer lifetime on a certainly model of a tube amp - go to
https://sound-au.com/valves/ht-delay.html
Under this URL in German
http://www.elektronikinfo.de/strom/roehrenirrtum.htm#Betrieb
- go to No 12 - is to read, that the correct delay time is important
For me it would be interesting to know, what recommend the tube manufacturers in this case (like Svetlana, JJ, Tesla and so on).
In the datasheets I don't find any advice regarded high voltage delay after switch on - go to
https://www.jj-electronic.com/images/stories/product/power_tubes/pdf/el34_e34l.pdf
If the delay applies B+ suddenly then there is a huge potential for damage. Only if
tube current are ramped up ( as when filament heats up) or a B+ is gradually increasing
over a time longer then the timeconstants in the circuit some value could be found.
The most common reason for delaying B+ is concerns for filter capacitors exceeding rated voltage
until tubes start to conduct. The cure here is "use higher voltage caps".
tube current are ramped up ( as when filament heats up) or a B+ is gradually increasing
over a time longer then the timeconstants in the circuit some value could be found.
The most common reason for delaying B+ is concerns for filter capacitors exceeding rated voltage
until tubes start to conduct. The cure here is "use higher voltage caps".
If the switch resp. the relay contact from the delay unit in the anode voltage rail behind the filter capacitor, the voltage at the filter elcap is much more higher than the nominal value (because this the voltage without the idle current load of the power stage tubes) - then you are right with your claim in post #122.
But if those switch resp. relay contact is located between anode secondary winding of the main transformer and the silicon rectifier (maybe trough a NTC inrush current limiter resistor) or even between the primary winding in case of separate main transformer for heating and anode voltage, I don't believe any potential for damage.
A sudden current rush while not in "working conditions" might cause higher currents then the electron
cloud can supply, thus forcing a huge amount of electrons that might rip cathode material with them.
Any appliance of B+ when cathode is hot should be done slower that any timeconstants in the amp, that
is as a "ramp-up" taking seconds.
Instead of "believing" read dave gillespies articles about this : http://tronola.com/html/maximize_tube_life.html
Taking the other view, none of the (audio)tube vendors has any advices against applying B+ at power on. Is'nt
that a clue ?
( adding comments about slow ramp up)
cloud can supply, thus forcing a huge amount of electrons that might rip cathode material with them.
Any appliance of B+ when cathode is hot should be done slower that any timeconstants in the amp, that
is as a "ramp-up" taking seconds.
Instead of "believing" read dave gillespies articles about this : http://tronola.com/html/maximize_tube_life.html
Taking the other view, none of the (audio)tube vendors has any advices against applying B+ at power on. Is'nt
that a clue ?
( adding comments about slow ramp up)
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If you look at Dave G's article it relates to specific set of conditions - which are quite different to the OP's method of switching the power transformer secondary. So post #125 is bringing up a type of operation that is effectively irrelevant, and should have had a heads up on that matter.
good advice - very interesting article. Thank you for this URL
under
https://web.archive.org/web/2011081...rise.com/host/tektronix/reference/cathode.asp
is mentioned this article:
"Thermionic Mysteries", by Ray Osterwald
Electric Radio magazine, Issue 54, October 1993 - maybe also to find in this book
https://www.ermag.com/product/hollow-state-design-2nd-edition/
(Thermatron semms to be an other term for tube resp. valve
https://kj7um.wordpress.com/2021/09/17/valve-vs-tube-vs-thermatron/)
just look at the high voltage amps designed in the past and how they implemented it, you gain a lot of insights, no need to relitigate what has been done in the past..
Hi Jan, bought two kits from DIY Store and in the process of putting the boards together. Two questions for the boards (v4):
1. My downstream of the delay is a MOSFET voltage regulator, this should be ok right?
2. You mentioned max 600V, what would min-V be to activate the board, say, for setting the delay time, without getting fried? Would >100VDC work?
Was puzzled by D5 on the board, but saw your previous post called for 12V zener.
Thanks for any info!
1. My downstream of the delay is a MOSFET voltage regulator, this should be ok right?
2. You mentioned max 600V, what would min-V be to activate the board, say, for setting the delay time, without getting fried? Would >100VDC work?
Was puzzled by D5 on the board, but saw your previous post called for 12V zener.
Thanks for any info!
what would min-V be to activate the board...?
Tested, setting a new on-time, at 40VDC in the end, but 15VDC seemed to work just fine too. Good thing, don't have to worry about frying my fingers with high-V.
Oddly, the minimum time seems to be 22-sec/11-flashes, can't do any lower. I'd like about 10-15 secs, but this would be fine too. Have to learn to be patient...
Thanks, Jan, for helping out the DIY community!
Tested, setting a new on-time, at 40VDC in the end, but 15VDC seemed to work just fine too. Good thing, don't have to worry about frying my fingers with high-V.
Oddly, the minimum time seems to be 22-sec/11-flashes, can't do any lower. I'd like about 10-15 secs, but this would be fine too. Have to learn to be patient...
Thanks, Jan, for helping out the DIY community!
I changed the supplied FDP12N60NZ for an IXTP01N100D after changing the amplifier it is used in to a higher (peak 540V) B+ value. The LED blinks and after the delay has passed stays on as set but the gate of Q3 doesn't get pulled up and it doesn't switch on.
It worked before the switch to the IXTP01N100D.
Does anyone have hints to troubleshoot and fix this?
Thank you very much.
It worked before the switch to the IXTP01N100D.
Does anyone have hints to troubleshoot and fix this?
Thank you very much.