<upsidedown@downunder.com> wrote in message news:bnedmdh9l3c3tma8j2b3bvsa2emmmmfrbu@4ax.com...> RF tubes are OK as long as you can amplitude them. Just add an > envelope detector (diode detector) and drive the speaker. Make sure > you handle the detector DC bias issue.Good point. Follow-up question: is there a 100MW+ microwave diode out there? ;-) Tim -- Seven Transistor Labs, LLC Electrical Engineering Consultation and Design Website: https://www.seventransistorlabs.com/
What is the most powerful vacuum tube ever made?
Started by ●August 3, 2018
Reply by ●August 5, 20182018-08-05
Reply by ●August 5, 20182018-08-05
On 05/08/2018 18:49, upsidedown@downunder.com wrote:> On Sun, 5 Aug 2018 16:30:39 +1000, Chris Jones > <lugnut808@spam.yahoo.com> wrote: > >> On 04/08/2018 14:44, Jeff Liebermann wrote: >>> On Sat, 04 Aug 2018 06:52:49 +0300, upsidedown@downunder.com wrote: >>> >>>> On Fri, 03 Aug 2018 18:54:10 -0700, Jeff Liebermann <jeffl@cruzio.com> >>>> wrote: >>>> >>>>> >>>>>> I'm looking into building the most pewerful tube audio amplifier >>>>>> possible. I'll be using 4 tubes in push-pull parallel. (per channel). My >>>>>> goal is at least 5000 watts RMS per channel (if possible). I will likely >>>>>> rewind some pole pigs (power pole transformers) for output transformers, >>>>>> and possibly use one of them in reverse for the power supply >>>>>> transformer, which should supply 3250 to 7500 volts to the plates (or up >>>>>> to 15KV if I use a different pole pig rated for higher primary voltage). >>>>> >>>>> You're probably ok at 3250 to 7500 volts, but 15kV will probably turn >>>>> your audio amplifier into an x-ray generator. Have your lead shielded >>>>> underwear handy. >>> >>>> Not an issue with full wave rectified 15 kVac. >>>> >>>> Below 25kVdc, the X-ray spectrum is just the continuum, above 25 kV >>>> nasty discrete X-ray lines will also appear. For this reason the power >>>> supply for old shadow mask CRTs also contained a shunt regulator (like >>>> the PD500 power triode) to limit the CRT anode voltage to 25 kV. >>> >>> Thanks. I couldn't recall at what voltage the problems start and was >>> too lazy to check. Looks like 20kV is where a vacuum tube starts to >>> produce x-rays. Interesting video shows how it works: >>> "Creating X-rays with a standard vacuum tube" >>> <https://www.youtube.com/watch?v=yLSu_UjrcUA> >>> >>> I've tried this experiment with various vacuum tubes. My voltage >>> source was smaller and only went to 25kV (powder coating paint gun): >>> <https://www.eastwood.com/eastwood-dual-voltage-powder-gun-starter-kit.html> >>> so I didn't see the continuous x-rays as in the video at 30kV. >>> >> >> >> I can't find it now, but I saw on youtube someone detecting significant >> amounts of xrays from a vacuum tube at 5kV. I think the problem is that >> most detectors are insensitive to low energy xray photons so people >> think there is no emission, but depending on the glass envelope, there >> might be, it is just hard to detect apart from by waiting for it to >> disrupt your DNA. Below 5kV there are definitely xrays within the vacuum >> tube, the question is whether or not they can get out. I would certainly >> suggest being very careful at even 5kV, and don't trust you xray >> detector to work for low energy xray photons, unless you have a good >> reason to. > > The continuous X-ray spectrum looks very much like black-body > radiation. There is a distinct peak, which frequency direct > proportional to frequency (hence inversely proportional to wavelength) > to the electron energy (in keV), while in standard black-body > radiation the wavelength is inversely proportional to temperature. > When viewed on a log-log graph, in both cases the slope is steeper on > the shorter wavelength side and so on. Some physics text books even > suggests that it _is_ the same phenomenon. > > At 5 keV, the total X-radiation is more than two orders of magnitude > below that of 25 keV, so not to worry about the radiation at 5 kV > anode voltage.Two orders of magnitude is not necessarily a sufficient safety factor. In a power amplifier I might well be running two orders of magnitude more anode current than a dental xray tube (there goes the "safety factor") and with no shielding that could do me a serious lot of damage within hours or less. The only options I would consider safe are either to calculate how much shielding would be needed and make sure it is there in the glass and metalwork, or obtain a detector that is provably sensitive to the wavelength of photons that could be present.
Reply by ●August 5, 20182018-08-05
On Sat, 04 Aug 2018 11:57:50 -0700, Jeff Liebermann <jeffl@cruzio.com> wrote:>which resulted in a horn length = 1692.3 cm or 17 meters long. That's >much longer than the Saturn 5 test horn, which suggests that it wasn't >intended to mimic engine vibrations. > >Interactively plugging numbers for the low end cutoff frequency, I >get: > low freq cutoff = 7.9 Hz > horn length = 756 cm >Close enough. So, the big horn was good for about 8Hz.The photo you presented is not the Redstone horn. The Redstone horn is rectangular and use folding techniques similar to the Klipsh Horn. That's the danger of being a URL and Wicki warrior. You don't know anything about what you're trying to disprove so you accept the first thing that looks close. A true obsession. John John DeArmond http://www.neon-john.com http://www.tnduction.com Tellico Plains, Occupied TN See website for email address
Reply by ●August 5, 20182018-08-05
On Sat, 04 Aug 2018 23:29:23 -0500, Tim Williams wrote:> 5kW is rather pedestrian for industrial applications; they're still > being maintained and sold, probably on the cheap side of things. > Commercial applications otherwise (like radiotransmitters) are basically > all solid state now, for good reason.My newsreader truncated the last bit of the title of this thread; it appeared to read, "What is the most powerful vacuum cleaner ever made?" I was about to remind the OP to use an 'OT' prefix. -- This message may be freely reproduced without limit or charge only via the Usenet protocol. Reproduction in whole or part through other protocols, whether for profit or not, is conditional upon a charge of GBP10.00 per reproduction. Publication in this manner via non-Usenet protocols constitutes acceptance of this condition.
Reply by ●August 5, 20182018-08-05
On Sun, 5 Aug 2018 23:31:38 +1000, Chris Jones <lugnut808@spam.yahoo.com> wrote:>On 05/08/2018 18:49, upsidedown@downunder.com wrote: >> On Sun, 5 Aug 2018 16:30:39 +1000, Chris Jones >> <lugnut808@spam.yahoo.com> wrote: >> >>> On 04/08/2018 14:44, Jeff Liebermann wrote: >>>> On Sat, 04 Aug 2018 06:52:49 +0300, upsidedown@downunder.com wrote: >>>> >>>>> On Fri, 03 Aug 2018 18:54:10 -0700, Jeff Liebermann <jeffl@cruzio.com> >>>>> wrote: >>>>> >>>>>> >>>>>>> I'm looking into building the most pewerful tube audio amplifier >>>>>>> possible. I'll be using 4 tubes in push-pull parallel. (per channel). My >>>>>>> goal is at least 5000 watts RMS per channel (if possible). I will likely >>>>>>> rewind some pole pigs (power pole transformers) for output transformers, >>>>>>> and possibly use one of them in reverse for the power supply >>>>>>> transformer, which should supply 3250 to 7500 volts to the plates (or up >>>>>>> to 15KV if I use a different pole pig rated for higher primary voltage). >>>>>> >>>>>> You're probably ok at 3250 to 7500 volts, but 15kV will probably turn >>>>>> your audio amplifier into an x-ray generator. Have your lead shielded >>>>>> underwear handy. >>>> >>>>> Not an issue with full wave rectified 15 kVac. >>>>> >>>>> Below 25kVdc, the X-ray spectrum is just the continuum, above 25 kV >>>>> nasty discrete X-ray lines will also appear. For this reason the power >>>>> supply for old shadow mask CRTs also contained a shunt regulator (like >>>>> the PD500 power triode) to limit the CRT anode voltage to 25 kV. >>>> >>>> Thanks. I couldn't recall at what voltage the problems start and was >>>> too lazy to check. Looks like 20kV is where a vacuum tube starts to >>>> produce x-rays. Interesting video shows how it works: >>>> "Creating X-rays with a standard vacuum tube" >>>> <https://www.youtube.com/watch?v=yLSu_UjrcUA> >>>> >>>> I've tried this experiment with various vacuum tubes. My voltage >>>> source was smaller and only went to 25kV (powder coating paint gun): >>>> <https://www.eastwood.com/eastwood-dual-voltage-powder-gun-starter-kit.html> >>>> so I didn't see the continuous x-rays as in the video at 30kV. >>>> >>> >>> >>> I can't find it now, but I saw on youtube someone detecting significant >>> amounts of xrays from a vacuum tube at 5kV. I think the problem is that >>> most detectors are insensitive to low energy xray photons so people >>> think there is no emission, but depending on the glass envelope, there >>> might be, it is just hard to detect apart from by waiting for it to >>> disrupt your DNA. Below 5kV there are definitely xrays within the vacuum >>> tube, the question is whether or not they can get out. I would certainly >>> suggest being very careful at even 5kV, and don't trust you xray >>> detector to work for low energy xray photons, unless you have a good >>> reason to. >> >> The continuous X-ray spectrum looks very much like black-body >> radiation. There is a distinct peak, which frequency direct >> proportional to frequency (hence inversely proportional to wavelength) >> to the electron energy (in keV), while in standard black-body >> radiation the wavelength is inversely proportional to temperature. >> When viewed on a log-log graph, in both cases the slope is steeper on >> the shorter wavelength side and so on. Some physics text books even >> suggests that it _is_ the same phenomenon. >> >> At 5 keV, the total X-radiation is more than two orders of magnitude >> below that of 25 keV, so not to worry about the radiation at 5 kV >> anode voltage. > >Two orders of magnitude is not necessarily a sufficient safety factor. >In a power amplifier I might well be running two orders of magnitude >more anode current than a dental xray tube (there goes the "safety >factor") and with no shielding that could do me a serious lot of damage >within hours or less. The only options I would consider safe are either >to calculate how much shielding would be needed and make sure it is >there in the glass and metalwork, or obtain a detector that is provably >sensitive to the wavelength of photons that could be present.The shortest X-ray wavelength possible from 1200 V is 1 nm. The peak wavelength is slightly longer, definitely only soft X-ray. At 25 kV, the minimum wavelength is 50 pm in the hard X-rays. I did not find a direct evidence that the X-ray bremsstrahlung (BS) continuum behaves like black-body (BB) continuum, but at least in the BB case, the total energy is proportional to the forth power. If this applies also to BS, the total BS at 25 kV would be 160000 times stronger than at 1200 V. So a 1-2 kV actual anode voltage (not power supply unloaded voltage) would not be an issue, unless you stick your nose constantly among the tubes, not recommended :-). Getting an electric shock in your nose is quite unpleasant and may affect concentration for a day. Done that, not recommended :-).
Reply by ●August 5, 20182018-08-05
In article <mQw9D.1980280$nr7.1461286@fx31.am4>, lugnut808 @spam.yahoo.com says...> > I can't find it now, but I saw on youtube someone detectingsignificant> amounts of xrays from a vacuum tube at 5kV. I think the problem is that > most detectors are insensitive to low energy xray photons so people > think there is no emission, but depending on the glass envelope, there > might be, it is just hard to detect apart from by waiting for it to > disrupt your DNA. Below 5kV there are definitely xrays within the vacuum > tube, the question is whether or not they can get out. I would certainly > suggest being very careful at even 5kV, and don't trust you xray > detector to work for low energy xray photons, unless you have a good > reason to.It should be easy to detect ionising radiation with an electroscope, and it is easy to build a cheap one of those.I remember doing it myself as a student, but I did have access to fine metal film, though not actually gold leaf. Mike.
Reply by ●August 5, 20182018-08-05
Mike Coon wrote:>It should be easy to detect ionising radiation with an electroscope, and >it is easy to build a cheap one of those.I remember doing it myself as a >student, but I did have access to fine metal film, though not actually >gold leaf. > >Mike.I have a few pen type radiation detectors like that, you charge the (electrometer) by pluggin it in into a unit, then put the pen in your pocket. At the end of the day you read the electroscope through a small window with a scale in the pen to see how much radiation you have been exposed too. Payed 10 Euro for the set.. Army surplus. Really nice stuff. http://217.120.43.67/nuclear/radiation_pen_IMG_6534.JPG And that is a raspberry webserver.
Reply by ●August 5, 20182018-08-05
On 05/08/2018 18:27, upsidedown@downunder.com wrote:> On Sun, 5 Aug 2018 23:31:38 +1000, Chris Jones > <lugnut808@spam.yahoo.com> wrote: > >> On 05/08/2018 18:49, upsidedown@downunder.com wrote: >>> On Sun, 5 Aug 2018 16:30:39 +1000, Chris Jones >>> <lugnut808@spam.yahoo.com> wrote: >>> >>>> On 04/08/2018 14:44, Jeff Liebermann wrote: >>>>> On Sat, 04 Aug 2018 06:52:49 +0300, upsidedown@downunder.com wrote: >>>>> >>>>>> On Fri, 03 Aug 2018 18:54:10 -0700, Jeff Liebermann <jeffl@cruzio.com> >>>>>> wrote: >>>>>> >>>>>>> >>>>>>>> I'm looking into building the most pewerful tube audio amplifier >>>>>>>> possible. I'll be using 4 tubes in push-pull parallel. (per channel). My >>>>>>>> goal is at least 5000 watts RMS per channel (if possible). I will likely >>>>>>>> rewind some pole pigs (power pole transformers) for output transformers, >>>>>>>> and possibly use one of them in reverse for the power supply >>>>>>>> transformer, which should supply 3250 to 7500 volts to the plates (or up >>>>>>>> to 15KV if I use a different pole pig rated for higher primary voltage). >>>>>>> >>>>>>> You're probably ok at 3250 to 7500 volts, but 15kV will probably turn >>>>>>> your audio amplifier into an x-ray generator. Have your lead shielded >>>>>>> underwear handy. >>>>> >>>>>> Not an issue with full wave rectified 15 kVac. >>>>>> >>>>>> Below 25kVdc, the X-ray spectrum is just the continuum, above 25 kV >>>>>> nasty discrete X-ray lines will also appear. For this reason the power >>>>>> supply for old shadow mask CRTs also contained a shunt regulator (like >>>>>> the PD500 power triode) to limit the CRT anode voltage to 25 kV. >>>>> >>>>> Thanks. I couldn't recall at what voltage the problems start and was >>>>> too lazy to check. Looks like 20kV is where a vacuum tube starts to >>>>> produce x-rays. Interesting video shows how it works: >>>>> "Creating X-rays with a standard vacuum tube" >>>>> <https://www.youtube.com/watch?v=yLSu_UjrcUA> >>>>> >>>>> I've tried this experiment with various vacuum tubes. My voltage >>>>> source was smaller and only went to 25kV (powder coating paint gun): >>>>> <https://www.eastwood.com/eastwood-dual-voltage-powder-gun-starter-kit.html> >>>>> so I didn't see the continuous x-rays as in the video at 30kV. >>>>> >>>> >>>> >>>> I can't find it now, but I saw on youtube someone detecting significant >>>> amounts of xrays from a vacuum tube at 5kV. I think the problem is that >>>> most detectors are insensitive to low energy xray photons so people >>>> think there is no emission, but depending on the glass envelope, there >>>> might be, it is just hard to detect apart from by waiting for it to >>>> disrupt your DNA. Below 5kV there are definitely xrays within the vacuum >>>> tube, the question is whether or not they can get out. I would certainly >>>> suggest being very careful at even 5kV, and don't trust you xray >>>> detector to work for low energy xray photons, unless you have a good >>>> reason to. >>> >>> The continuous X-ray spectrum looks very much like black-body >>> radiation. There is a distinct peak, which frequency direct >>> proportional to frequency (hence inversely proportional to wavelength) >>> to the electron energy (in keV), while in standard black-body >>> radiation the wavelength is inversely proportional to temperature. >>> When viewed on a log-log graph, in both cases the slope is steeper on >>> the shorter wavelength side and so on. Some physics text books even >>> suggests that it _is_ the same phenomenon. >>> >>> At 5 keV, the total X-radiation is more than two orders of magnitude >>> below that of 25 keV, so not to worry about the radiation at 5 kV >>> anode voltage. >> >> Two orders of magnitude is not necessarily a sufficient safety factor. >> In a power amplifier I might well be running two orders of magnitude >> more anode current than a dental xray tube (there goes the "safety >> factor") and with no shielding that could do me a serious lot of damage >> within hours or less. The only options I would consider safe are either >> to calculate how much shielding would be needed and make sure it is >> there in the glass and metalwork, or obtain a detector that is provably >> sensitive to the wavelength of photons that could be present. > > The shortest X-ray wavelength possible from 1200 V is 1 nm. The peak > wavelength is slightly longer, definitely only soft X-ray. > > At 25 kV, the minimum wavelength is 50 pm in the hard X-rays. > > I did not find a direct evidence that the X-ray bremsstrahlung (BS) > continuum behaves like black-body (BB) continuum, but at least in the > BB case, the total energy is proportional to the forth power. If this > applies also to BS, the total BS at 25 kV would be 160000 times > stronger than at 1200 V.Without meaning to state the bleedin' obvious, but energy in > energy out. The energy of an xray photon is proportional to the accelerated electron voltage, which in most instances is proportional to V.> So a 1-2 kV actual anode voltage (not power supply unloaded voltage) > would not be an issue, unless you stick your nose constantly among the > tubes, not recommended :-). > > Getting an electric shock in your nose is quite unpleasant and may > affect concentration for a day. Done that, not recommended :-).I have a vision of Jar Jar Binks in my mind after he paralysed his heads! -- Mike Perkins Video Solutions Ltd www.videosolutions.ltd.uk
Reply by ●August 6, 20182018-08-06
On Sat, 4 Aug 2018 10:58:35 +0300, Tauno Voipio <tauno.voipio@notused.fi.invalid> wrote:>400 Hz hum is more annoying than the customary 50/60 Hz >hum, so you'll need better filtering there. Been there, >done that, in 35 years in avionics engineering.Much of the 50/60 Hz hum problem is/was due to grounding practices, especially with stage equipment. - unbalanced signal connections were used - the signal ground in each device was directly connected to chassis - PE and N connected together into PEN in each mains socket ((TN-C) (- SCR controlled stage lights connected to same mains feed, same PEN) Fixing these problems helps solve a lot of hum problems on 50/60 Hz, so why not on 400 Hz. I admit that the ear is much more sensitive on 400 Hz than on 50/60 Hz, so more care is needed.
Reply by ●August 6, 20182018-08-06
upsidedown@downunder.com <upsidedown@downunder.com> wrote:> On Sat, 4 Aug 2018 10:58:35 +0300, Tauno Voipio > <tauno.voipio@notused.fi.invalid> wrote: > >>400 Hz hum is more annoying than the customary 50/60 Hz >>hum, so you'll need better filtering there. Been there, >>done that, in 35 years in avionics engineering. > > Much of the 50/60 Hz hum problem is/was due to grounding practices, > especially with stage equipment. > > - unbalanced signal connections were used > - the signal ground in each device was directly connected to chassis > - PE and N connected together into PEN in each mains socket ((TN-C) > (- SCR controlled stage lights connected to same mains feed, same PEN) > > Fixing these problems helps solve a lot of hum problems on 50/60 Hz, > so why not on 400 Hz. > > I admit that the ear is much more sensitive on 400 Hz than on 50/60 > Hz, so more care is needed.Listen on aircraft radio frequencies and you'll hear that 400Hz whine on a lot of transmissions. With a little care it could probably be avoided, but likely nobody cares as it isn't a safety issue. When a similar system had 50/60Hz hum, you wouldn't even hear it as the typical communication receiver has a high-pass to filter CTCSS and the small speaker wouldn't do much at those frequencies. Of course that isn't true for a stage audio system...
