Most amazing dumpster dive ever!!!!

[GK]

Originally Posted by ikoflexer

Transformers eh? I recently scored something good too, a 2400V transformer, 5KVA,

That's not a transformer. An old 3-phase unit. LandRover gearbox for size comparison.

[tomtt]

the first 'cerafine' caps this poster acquired,

were from an amp, on the side of the road ...








a a minor epic -

Abandoned Twins Rescued !


14441/386

[rdf]

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+.

[GK]

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

[jackinnj]

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.

[GK]

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.

[BudP]

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

[GK]

Ya workin' on transforma EnABL patterns now?

[BudP]

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

[GK]

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.