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#1
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Slow PowerUp Replacement Rectifier For 5V4
6106 or 6087? 75mA current rating on these.
GZ-37? I've heard they heat slow. Limitation to input cap size with these. Jeff Goldsmith Armand wrote: Is there a drop in replacement for the 5V4 that has a slower voltage rise? Thanks. |
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#2
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Armand wrote: Is there a drop in replacement for the 5V4 that has a slower voltage rise? Thanks. 5AR4 / GZ34 should work as a drop-in replacement, with slightly lower (about 5%) filament current requirement. I don't have specs on warm-up characteristics available though, so don't know if it would actually gain you anything. Cheers, Fred -- +--------------------------------------------+ | Music: http://www3.telus.net/dogstarmusic/ | | Projects: http://dogstar.dantimax.dk | +--------------------------------------------+ |
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#3
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Armand wrote: Is there a drop in replacement for the 5V4 that has a slower voltage rise? Thanks. 5AR4 / GZ34 should work as a drop-in replacement, with slightly lower (about 5%) filament current requirement. I don't have specs on warm-up characteristics available though, so don't know if it would actually gain you anything. Cheers, Fred GZ34 has a 3A (or 2.8A) filament draw as opposed to the 2A (1.8A) draw of a 5V4 / GZ32. 5V4 has a separate cathode, so it is already a pretty slow warm up. However, my 5V4 tend to warm up faster than my mullard GZ34, which is verrry slow (10 seconds or more) -- +--------------------------------------------+ | Music: http://www3.telus.net/dogstarmusic/ | | Projects: http://dogstar.dantimax.dk | +--------------------------------------------+ |
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#4
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Hi RATs!
Slow only on initial power up after period of rest. If you get a brief power outage, all goodness and purity are lost. Here in AZ, power outages are never brief, so, No Problema! If you really want B+ to behave, install separate switch with a relay to open if power drops. Remote control is optional. Think of it as a sport, and, go for the Gold! Happy Ears! Al Alan J. Marcy Phoenix, AZ PWC/mystic/Earhead |
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#5
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Jeff Goldsmith wrote:
6106 or 6087? 75mA current rating on these. GZ-37? I've heard they heat slow. Limitation to input cap size with these. No, not really. The peak current limit is the same on both the GZ34 and 37 (750mA), so the cap. size limit should be the same also. There's no size limit mentioned in the data sheet. You can find the GZ37 datasheet he http://frank.pocnet.net/sheets/129/g/GZ37.pdf Best regards, Mikkel C. Simonsen Jeff Goldsmith Armand wrote: Is there a drop in replacement for the 5V4 that has a slower voltage rise? Thanks. |
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#6
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"Mikkel C. Simonsen" wrote: Jeff Goldsmith wrote: 6106 or 6087? 75mA current rating on these. GZ-37? I've heard they heat slow. Limitation to input cap size with these. No, not really. The peak current limit is the same on both the GZ34 and 37 (750mA), so the cap. size limit should be the same also. There's no size limit mentioned in the data sheet. You can find the GZ37 datasheet he http://frank.pocnet.net/sheets/129/g/GZ37.pdf Best regards, Mikkel C. Simonsen Jeff Goldsmith Armand wrote: Is there a drop in replacement for the 5V4 that has a slower voltage rise? Thanks. The GZ34 could be used as a series diode, with both diodes within paralleled, and in series with the flow of DC OUT of the first cap from a silicon rectifier, say before the choke which feeds the second cap in a CLC filter. This way the size of C1 can be 470 uF, no worries, and the tube diodes are slow to turn on, yet when they are on the series R would be about 15 ohms, and current ability would be high. Thus the initial surge of current at turn on is controlled. However surge currents in the tubes are not a problem from a cold start. Its the restart when everything is hot that causes a current surge. Directly heated cathode tube rectifiers generate a high peak voltage well before the output tubes start conducting, and yet this doesn't seem to cause problems, except that the supply caps must be able to take the voltage peak surge. Brief power interruptions with the diode cathode still hot will cause a current surge when power comes back on. In my big amps I use a 20 watt R in series with the HT winding, and this is shunted by a relay after 4 seconds. If there is a turn off then turn on of the power over a period longer than 0.5 seconds, then the relay shunting the series R must go through the 4 second cycle. Then the R limits the current fine. The control circuit is a couple of diodes and transistors, and an RC time constant circuit. In normal cold start conditions, the series R limits inrush current from the mains, and after 4 seconds, B+ goes near to its final value, then a lesser surge occurs when the R is shunted. The same sort of cascaded smaller than otherwise current surges occur during brief power interuptions. The benefit of all this is that the mains fuse doesn't have to be such a high value, as it would if you have high inrush currents, especially with silicon rectifiers, and the typically monster values of capacitors I like to use. If you have a high value of mains fuse, your protection against catastrophe is reduced, and it may cost you your house, since a transformer might get a fault, overheat, catch on fire, and set the house alight, before the bleedin fuse blows. The mains fuse needs to be a value just above that which causes nuisance blows under normal conditions. If an amp draws say 220 VA from the mains, and the mains is 110v, then you have 2 amps of input flow. If the fuse was 4 amps, then there has to be 440VA of input before it might blow. If it was 6 amps, then 660 VA of input is needed, but in practice, a fuse might not blow until the current goes 20% above the rated amperage, and stays there for awhile. So if an amp draws 800 watts before the fuse blows, it could be because the bias has failed, and serious collateral damage could occur before a the damage eventually causes a direct short circuit. Fuses on the B+, between C2 and the centre tap of the OPT are a must, if there is no protection circuits operating off a 10 ohm R in the cathode circuits of each and every outout tube. In the old days of tube amps, few makers fitted protection against excessive cathode currents, or had any indication that the balance of output tube current was correct. Its these very old bangers that are most prone to failure, and some form of fault indication using a few SS parts on a small board can now be easily fitted. Current surges in power interupted output stages can be reduced by the size of large values of C&L in CLC type filters, and I'd say the series tube diodes would help, and be quite OK for most class A or AB amps, where serious regulation isn't really necessary. I know a guy who uses a GZ34 in series with his SE 845 amp supply caps, and he says it works quite nicely. Patrick Turner. |
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#7
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Henry 007 wrote: [...] Really??? According to RCA RC-27, for 5AR4/GZ34: "Heater: volts (ac/dc), 5; amperes, 1.9." Where did you get your data? It appears that i pulled it out of thin air, 1.9A is indeed correct! Wow, thats wierd, I was sure it was 3A... Cool Henry Ah, maybe you were confusing with the common 5U4, with its 3A filament. Cheers, Fred -- +--------------------------------------------+ | Music: http://www3.telus.net/dogstarmusic/ | | Projects, Vacuum Tubes & other stuff: | | http://www.dogstar.dantimax.dk | +--------------------------------------------+ |
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#8
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interesting-this days I was occupied with solving one simple problem:
due to power blackouts (especially really short ones) internal automatic switch (more sort of automatic fuse-40A) of our tube transmitter (99.1 MHz ,2.5KW) is often clicked down. problem is-(hehe) xmitter is just 15Km from studio. powering cycle is pretty normal-90 secs of 5A from 220 main (just heating),then 17A when 2700V is clicked. but in moment of short outage,thingie like to pull more than 40A from wall,just because Ht relay circuit is too slow for off state. after some thinkin',I just use one greeeeeesy 3phase contactor via Omron programming delay relay. catch is-I wire contactor to take his own coil via "working" accessory contacts and delay relay is wired through "steady" contacts. so,relay just give initial impulse to contactor coil,then is ( delay relay) switched off when lifter goes down (down to "on" position) . so ,when you power up delay circ-delay relay after 5 secs give power to lifter's coil,then stays without power; durin' blackout-lifter goes up (switching off bloody xmiter) ,just then delay relay again is on power line-after 5 secs he gives impulse to lifter's coil etcetc. I must make something similar (just smaller) for my home tube gear. hehe-this wooden box with "anti blackout circ" and main filter and voltage meter will be biggie............ -- Choky Prodanovic Aleksandar YU "TubeGarden" wrote in message ... Hi RATs! Slow only on initial power up after period of rest. If you get a brief power outage, all goodness and purity are lost. Here in AZ, power outages are never brief, so, No Problema! If you really want B+ to behave, install separate switch with a relay to open if power drops. Remote control is optional. Think of it as a sport, and, go for the Gold! Happy Ears! Al Alan J. Marcy Phoenix, AZ PWC/mystic/Earhead |
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#9
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Thanks for all the responses.
I was thinking about the 5AR4 which does have one of the slowest power-up times but wasn't sure if the different rec would affect the plate voltage of the El34 output tubes. Will it? Thanks In article , says... Armand wrote: Is there a drop in replacement for the 5V4 that has a slower voltage rise? Thanks. 5AR4 / GZ34 should work as a drop-in replacement, with slightly lower (about 5%) filament current requirement. I don't have specs on warm-up characteristics available though, so don't know if it would actually gain you anything. Cheers, Fred -- +--------------------------------------------+ | Music: http://www3.telus.net/dogstarmusic/ | | Projects: http://dogstar.dantimax.dk | +--------------------------------------------+ |
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#10
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Armand wrote: Thanks for all the responses. I was thinking about the 5AR4 which does have one of the slowest power-up times but wasn't sure if the different rec would affect the plate voltage of the El34 output tubes. Will it? Thanks No, at least not significantly. It will certainly be within the 10 percent generally considered acceptable tolerance. Cheers, Fred -- +--------------------------------------------+ | Music: http://www3.telus.net/dogstarmusic/ | | Projects, Vacuum Tubes & other stuff: | | http://www.dogstar.dantimax.dk | +--------------------------------------------+ |
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