#211
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Yeah, building a power supply like that will really show you how much power those filaments need. I think I had to use a 15A filament transformer to run my GE 802's power supply, where the filaments consumed something like 12A. What's the filament draw on your set going to be?
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#212
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No idea, but this filament PTX came from an organ which always have a bazillion 12AU7's in them. I don't think it will be a problem as far as that goes, I just hope I can come up with all the B+ supplies it's gonna need. I think right now I'm looking at a 250-ish rail, 380-ish rail, some yet unknown B- supply (maybe around ~100), and possibly a small positive bias supply. Interestingly, one of the filament windings on the B+ PTX is 6.6v center tapped... I guess I could always run 5U4's at a volt more than normal, but perhaps 3DG4's would be more appropriate? Then again, it's entirely possible that the voltages will get a little lower once the thing is loaded down really good.
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#213
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Quote:
Sorry... late night humor Last edited by Kevin Kuehn; 07-24-2011 at 02:31 AM. |
#214
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Quote:
On a twin-tube "B" supply, if one tube opens a filament, the other tube promptly melts before the user notices and can shut the system off. On 5U4's this problem seemed to be worse with the fat G's and first generation GT's than with the GB's If the filaments were wired in series, this would protect the second tube. Are the tubes in the picture from the organ? If not, any idea what tubes the organ used? |
#215
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Quote:
The idea is that if one tube shorts and blows the filament open, the remaining tube will be the only load on the transformer. The B+ will drop, but the transformer will not be overloaded. A 6.6 volt filament winding is sometimes used if the power supply is on one chassis and the load circuitry is on another separated by 2 to 4 feet of heavy cable. The voltage drop through that cable can be in the range of ~0.3 volt if the filament draw is substantial. Cliff |
Audiokarma |
#216
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Quote:
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#217
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Because the damper tubes in those days may suffer cathode to filament breakdown, was there originally in the prototype previously provision for a separate filament winding for the damper?
Terry Last edited by Penthode; 07-24-2011 at 11:18 AM. Reason: updated |
#218
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No, only an isolation transformer off the heater string that supplies all the other tubes.
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#219
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Please let me know what else you may need for the power supply. If I have anything you need, it's yours for the shipping cost.
I have, literally, a ton of PS iron, etc.. Rick |
#220
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OK, thanks for the offer! Right now I have the chassis Bob gave me, with a pair of tranformers that look like they are up to the task, twin ST glass 5U4G rectifiers and enough stuffable caps to build something useful. If I need anything more, I'll keep you in mind.
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Audiokarma |
#221
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Update: I may have a line on a very nice cabinet for this chassis. It's a 9-T-79, which uses the 19" tube. It's got 4 doors, 2 for the screen and 2 for the speaker. Very classy. The seller says it's 24" deep, which should be more than enough to hold the entire color chassis without any of it sticking out. Only question is, will I be able to make a nice bezel to adapt this cab to the smaller 16" pix tube mask?
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#222
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I've already got an idea on how to make a mask for it, we could whip one out in less than a day. ( If nothing goes wrong :3 )
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My TV page and YouTube channel Kyocera R-661, Yamaha RX-V2200 National Panasonic SA-5800 Sansui 1000a, 1000, SAX-200, 5050, 9090DB, 881, SR-636, SC-3000, AT-20 Pioneer SX-939, ER-420, SM-B201 Motorola SK77W-2Z tube console McIntosh MC2205, C26 Last edited by zenithfan1; 08-29-2011 at 10:11 PM. |
#223
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Here's the set in question:
http://nashville.craigslist.org/fuo/2520420291.html I already sent a payment through Paypal, but she has never used it before so we'll see if it goes through OK. If so, I have a job up on U-Ship right now to get it here. There is also another potential Bob alerted me to, this time on Ebay: http://www.ebay.com/itm/RCA-Victor-T...item45fcd745e4 Of the 2, the second one would be better since it has the smaller 16" pix tube. The developmental tube would fit right in, no mods at all. I have to admit though, I really like the looks of the 19" one with it's double doors and all. I suspect I will end up with both, and I'll have to choose. I have promised a friend first crack at whatever I don't need (tubes/chassis), anything else will be offered here at a very low price.
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Evolution... Last edited by miniman82; 04-15-2012 at 03:01 PM. |
#224
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Looks like two 16" sets to me...?
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tvontheporch.com |
#225
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I thought so too, but she looked at the back of the first set at my request: it's a 9-T-79, which uses the 19AP4.
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Audiokarma |
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