Some of my freebie iron, which I've been testing this evening. The baby of the three is a medical grade (salvaged from medical equiptment) 1900VA toroid, 240Vpri / 115Vsec with an electrostatic screen. Just what I need for powering my American test equiptment. Yahoo. I'll be putting this one into my power rack for the 115V distribution.
The other two transformers are a pair of single-phase, 240Vpri / 2150Vsec of a slightly higher power rating, which I'm about to clean up and install into a couple of Broadcast HF transmitters that I'm converting to single-phase, that use multiple 4CX1000A's with 3kV on the plate. I do the filtering with some decent chokes and a string of 400VDC electrolytics. These can give you a bit of a tickle.
The other two transformers are a pair of single-phase, 240Vpri / 2150Vsec of a slightly higher power rating, which I'm about to clean up and install into a couple of Broadcast HF transmitters that I'm converting to single-phase, that use multiple 4CX1000A's with 3kV on the plate. I do the filtering with some decent chokes and a string of 400VDC electrolytics. These can give you a bit of a tickle.
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The prior denizens of our ham radio station at high school had used the power supply and carcase of a broadcast transmitter -- I think that they used a DX35 and SB10 as the exciter/ssb generator -- to get rid of the tickle they had a discharge rod made of phenolic resin. The filter caps were only a few mmf, high voltage probably leaking PCB's.
Transformers eh? I recently scored something good too, a 2400V transformer, 5KVA, just what I needed for my next power triode project 😀
My other good find was a mass spectrometer, choke-full of instrumentation opamps and adcs, a fully functional tube Boonton capacitance bridge, a portable gas analyzer (don't know what to do with that), and some other small things. What can I say, my first choice would be a military dumpster, but for lack of that I'll just settle for the university dumpster. 🙄
My other good find was a mass spectrometer, choke-full of instrumentation opamps and adcs, a fully functional tube Boonton capacitance bridge, a portable gas analyzer (don't know what to do with that), and some other small things. What can I say, my first choice would be a military dumpster, but for lack of that I'll just settle for the university dumpster. 🙄
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My 'best' dive was two ford estste cars full of 1/4" copy master tapes (insurance copies) dumpstered by an international UK studio. The haul included mono tapes from the 1950s!! along with some truly hot collectors stuff!
This is encouraging me to go down there this afternoon.
Penn State and Carnegie Mellon stopped throwing stuff out -- they now sell via EBay.
Penn State and Carnegie Mellon stopped throwing stuff out -- they now sell via EBay.
We have a so called surplus swap shop and the policy is to put all the stuff people don't need in there, the reason being that University staff would get priority in buying it for a few bucks. The trouble is that only furniture makes it to the shop. When I asked about electrical devices of any kind the guy looked at me surprised and said: "we don't even get that, nobody wants it, we leave it at the dump site" (meaning each department has their own little dump area). So, there, we're way behind CMU and Penn State 😀
I bid on a reflow oven which Penn State had for sale last year, thought I could get it on the cheap -- so such luck.
We usually dig up cool stuff from the dumpster others throw away at the uni. It gets reused for constructing all kinds of fancy apparatus. Even if it's only a casing for putting in stuff we use to drive our lasers with.
Today we cannibalized an old Tektronix oscilloscope. The leftovers were to be dumped. They contained a cool 17-0-17 trafo that I kept. It may power my next TDA2030 amp. 😎
The most amazíng thing we found was an electron microscope. We wanted to fix it but decided against it yesterday. 🙁
Today we cannibalized an old Tektronix oscilloscope. The leftovers were to be dumped. They contained a cool 17-0-17 trafo that I kept. It may power my next TDA2030 amp. 😎
The most amazíng thing we found was an electron microscope. We wanted to fix it but decided against it yesterday. 🙁
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I use bleeder resistors. Modern HV electrolytics in series are the way to go. The bleeder resistors also ensure voltage sharing (in parallel with each cap).
I'm slowly substituting all my PCB filled caps and making a pile for the EPA.
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That's not a transformer. An old 3-phase unit. LandRover gearbox for size comparison.
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the first 'cerafine' caps this poster acquired,
were from an amp, on the side of the road ...
a a minor epic -
http://www.diyaudio.com/forums/everything-else/148089-abandoned-twins-rescued.html
14441/386
were from an amp, on the side of the road ...
a a minor epic -
http://www.diyaudio.com/forums/everything-else/148089-abandoned-twins-rescued.html
14441/386
Pfft. Those aren't caps. These are caps. Three 4uF @ 5000V, one 8 uF @ 4000V. Not yet sure what they're good for, but I have them. FM transmitter decommission. Also stripped all the 15 kV wire seen as jumpers here for high voltage B+.
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Well since we aren’t talking audio gear any more I might a well post the whole transmitter, as it basically was a “dumpster dive” freebie after all. I got my hands on two of these, along with a bunch of spare tubes (4XC1000A’s, 6080, 6146’s, etc), tuning tools, red manometer fluid, etc, etc.
One transmitter was about 50% ratted, so I finished it off for spares and invaluable future homebrewing parts, finally sending the stripped bare cabinet off for scrap.
The one in the picture was only partially ratted, and I’ve now got it nigh on 100% operational, with the 3kV plate supply operating on single phase mains.
There are some minor repairs to make to one of the H.T regulators (someone replaced a couple of VR tubes with zeners, but screwed it up a bit), replace the (very worn and bloody noisy) blower bearings, substitute the ancient capacitors with new ones and finish upgrading the burnt out indicator globes in the switchgear with white LED’s.
The thing is basically two (almost identical) independent class AB1 linear amplifiers in one frame, which share the same power supplies and control circuity. The amplifiers can be run simultaneously or independently. Only ~100mW/50ohms drive is required from an AM, SSB or FSK exciter. The lower TX shelf is tunable from 2 – 6MHz while the upper TX shelf is tuneable from 5 - 12MHz. I’ll eventually be operating the lower one on 80m and the upper on 40m
One transmitter was about 50% ratted, so I finished it off for spares and invaluable future homebrewing parts, finally sending the stripped bare cabinet off for scrap.
The one in the picture was only partially ratted, and I’ve now got it nigh on 100% operational, with the 3kV plate supply operating on single phase mains.
There are some minor repairs to make to one of the H.T regulators (someone replaced a couple of VR tubes with zeners, but screwed it up a bit), replace the (very worn and bloody noisy) blower bearings, substitute the ancient capacitors with new ones and finish upgrading the burnt out indicator globes in the switchgear with white LED’s.
The thing is basically two (almost identical) independent class AB1 linear amplifiers in one frame, which share the same power supplies and control circuity. The amplifiers can be run simultaneously or independently. Only ~100mW/50ohms drive is required from an AM, SSB or FSK exciter. The lower TX shelf is tunable from 2 – 6MHz while the upper TX shelf is tuneable from 5 - 12MHz. I’ll eventually be operating the lower one on 80m and the upper on 40m
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Looks like a "smoker" -- you can clean it up with a bit of TSP or TSP-pf (sodium meta-silicate) -- nicotine stains easily removed.
I have been selling off my Hallicrafters collection.
I have been selling off my Hallicrafters collection.
Thanks for the tip, I use that for PCB developer, so I've got it handy. Besides the stains, the paint seems to have gone off. The other TX was left in the sun for a long time before I got it, and was much worse. The surface of the paint had actually gone powdery in the most faded places, and would leave your clothes and hands a whitish blue after shifting the thing around. Fortunatly this one isn't that bad. I was thinking a cut and polish with T-cut.
I would be very interested in any detail pictures you might be willing to take and provide, of the transformers involved. That being my professional activity, when applicable.
Bud
Bud
GK,
Nope, just have many folks going on about how nice it would be if I would learn how to do what I do, at ridiculous voltage levels.
EnABL was just a means to an end, a way to eliminate the speaker as the major cause of distortion and egregious in room mis-activity, so I could make some value judgments to go along with the quantitative gunk, that really only hints at what the iron monsters might sound like.
Seeing the solutions used for a 3kva OPT would interest me from a professional point of view. I was never in a situation where I could learn how to deal with more than 800 va or less than 20kva. Thought maybe I had insulted you enough that you would fob me off with some pictures just to get me to shut up.
Bud
Nope, just have many folks going on about how nice it would be if I would learn how to do what I do, at ridiculous voltage levels.
EnABL was just a means to an end, a way to eliminate the speaker as the major cause of distortion and egregious in room mis-activity, so I could make some value judgments to go along with the quantitative gunk, that really only hints at what the iron monsters might sound like.
Seeing the solutions used for a 3kva OPT would interest me from a professional point of view. I was never in a situation where I could learn how to deal with more than 800 va or less than 20kva. Thought maybe I had insulted you enough that you would fob me off with some pictures just to get me to shut up.
Bud
OK, I tell you what, I’ll make some transformer pictures this evening. That one I showed in post 131 is probably in the order of 15kVA, 2200V. It came from one of my TX’s that uses four 4CX1000A’s in PPP. That is the amount of iron you need to run 4 of these in class AB1 linear at full power on a continuous basis, with tight plate voltage regulation and without overheating.
I'm completing the single phase (and 160m) conversion on that TX now. With the excitation curtailed to the legal limit, I will be likely be the only one on 1.8MHz running legal limit AM with a TX that's just loafing along in pure class A. Only in winter though - the ~4kW input power at idle makes the shack a little toasty.
I always chuckle when I see a homebrew HAM rig with a 4CX1000A or two inside, that’s small and light enough to sit on ones operating bench.
I'm completing the single phase (and 160m) conversion on that TX now. With the excitation curtailed to the legal limit, I will be likely be the only one on 1.8MHz running legal limit AM with a TX that's just loafing along in pure class A. Only in winter though - the ~4kW input power at idle makes the shack a little toasty.
I always chuckle when I see a homebrew HAM rig with a 4CX1000A or two inside, that’s small and light enough to sit on ones operating bench.
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