Largest resistor I've ever seen

[Phil_S]

I found this in the RCA PA amp that was recently gifted to me. It is the physically largest resistor I have ever seen. It measures 4" long x 0.75" outside diameter. There are 3 terminals. Between the first two (~1") its marked 3000 and between the 2nd and 3rd terminal marked 20000 (20K). It is permanently mounted (until I decide whether to drill out the rivets).

One end is grounded. The other seems to be connected to the PT but I can't exactly figure what it does. I've already snipped some wires in these pics.

I thought maybe this is curious enough to use for show and tell and why its in Garage Talk rather than Technical. BTW, it meters close what it is marked.

Any idea how many watts this thing is rated?

[Reeltarded]

3 minutes in a 1200w microwave if frozen, like 1:45 if thawed.

Yeah, itsa biggun.

[martin manning]

Yeah? I've seen bigger: http://www.ohmite.com/cat/res_270.pdf

[VacuumVoodoo]

Still bigger

[img:632:515]http://www.sklep.fpnnysa.com.pl/userdat ... ed6f56.jpg[/img]
[img:800:600]http://obrazki.elektroda.net/69_1264976347.jpg[/img]

[Reeltarded]

We should put them in a pool and watch them fight to the death. Might want to bring something to do and some beer.

Those would make great plate loads.

[John_P_WI]

You guys haven't seen anything yet, back in the 90's I was involved in the development of a 5500 kw dissipation dynamic braking resistor for the EMD locomotive SD90MAC. The resistor was about the height and diameter of a patio table and used stainless steel punched and formed as the resistive elements in a stack of 7. Yes, that was 5500 kilo watts dissipation!

The crane and transportation resistor division that I worked for was divested and much of it was sold to Mosebach in Pittsburgh, soon after that the SD90mac locomotive was shelved as it was prone to operating failures - basically too much power for the platform. Good memories a long time ago.

The high powered labs were truly a Frankenstein type lab

[Leo_Gnardo]

You guys haven't seen anything yet, back in the 90's I was involved in the development of a 5500 kw dissipation dynamic braking resistor for the EMD locomotive SD90MAC. The resistor was about the height and diameter of a patio table and used stainless steel punched and formed as the resistive elements in a stack of 7. Yes, that was 5500 kilo watts dissipation!

What color stripes were painted on it?

The one in that old RCA amp - there was something similar in the first run of Crown DC-300 power amps. Big custom made "hot dog" resistor.

College physics lab had some huge 1 ohm resistors, made from stacks of square graphite "cookies" bracketed in a steel frame. About 12-15 inches long, 2x2" "cookies"

[Phil_S]

Hmmm...mine's bigger...I think Miles has the right idea. LOL! You guys are too much!

It's stuck in there. Shame to waste it. I'll have to figure where it goes in the B+ ladder. Did a bit of PT testing today and found the HT is 839VAC unloaded. The amp only ran one pair of 6L6, so I figure this PT is "soft." I might have to build out the power supply and put tubes in sockets to see what actually happens. Imawondering about the choke. Could it have been choke input? Lotta weird wiring in there that I couldn't wrap my amateur eyesandbrain around.

[Leo_Gnardo]

Who knows you may even have one of those "back bias" circuits as drawn out in the schematics at the end of the RCA receiving tube manual.

Soft power supply in a PA . . . well, if you want some cheap compression that'll do it.

[passfan]

I have seen the center tap of the main B+ resistored to ground to limit the current draw.

[Meat&Beer]

At the test facility we have for powering up/test driving/etc the trains I work on, there's these four MAMMOTH resistors! Definitely the biggest I've ever seen, probably most of you too! No idea what they used them for, one looks to be busted. On a high shelf collecting dust, likely forgotten about, but nothing like that evades an eye like ours, does it? (Car in the background is bound for Chicago.)

[Reeltarded]

Somebody please use one as a handle on a fender looking amp.

[martin manning]

Ya, built-in dummy-load, and bonus handle warmer!

[Reeltarded]

Is this the answer to dropping B+ 250v?

[Meat&Beer]

I couldn't see their voltage rating, (probably disgusting) but the one I'm holding was a 4.5ohm, the one behind a 10ohm, not sure about the others. I don't think that'll knock 'er down much!