Film-Tech Forum ARCHIVE: Non-Standard Resistor needed

This is topic Non-Standard Resistor needed in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Jon Bartow (Member # 241) on 03-04-2003, 08:18 PM:

Anyone know of a supplier for a 20W 75K enamel resistor? It's not exactly a "standard" size.

Posted by Phil Hill (Member # 371) on 03-04-2003, 08:39 PM:

Not sure what you mean by a "standard" size. If it's the run-of-the-mill axial-lead vitreous enamel power resistor, then it is indeed a standard resistor. Check out Ohmite for a part # B20J75K (I think). I'm sure they have a place listed where you can buy it. If that's not the type, they have many others.

>>> Phil

Posted by Jon Bartow (Member # 241) on 03-04-2003, 08:53 PM:

I'm actually looking for a lug-type enamel power resistor, not an axial lead. Ohmite doesn't list this part number, but it should be L20J75K ( L lug 20 20-watt J75K 75K ohm )
The B20J75K is an axial lead type and would not be an exact replacement for the current unit, however, if all else fails, it could be made to work.
FWIW this is to replace R18 in an Altec 1570B
Jonathan

Posted by Jim Spohn (Member # 1547) on 03-05-2003, 10:04 AM:

Contact Mouser Electronics at (800) 346-6873
or Newark Electronics at (800) 263-9275 or Digi-Key Electronics at (800)344-4539 All of those places should be able to supply what you need.....Jim

Posted by Jon Bartow (Member # 241) on 03-05-2003, 04:39 PM:

Already tried Mouser and Newark, just tried Digi-Key. No go.
Ohmite doesn't make exactly what I need. Don't know who does.
Jonathan

Posted by John Hawkinson (Member # 1135) on 03-05-2003, 04:40 PM:

Did you actually try asking them as opposed to their catalogs?

--jhawk

Posted by Mark Gulbrandsen (Member # 72) on 03-05-2003, 06:31 PM:

Jon,
You might have to make it up out of several different values in parallel to arrive at the value you need. High value - high wattage resistirs are not very common these days. Also consider using a resistior with a variable tap. I'll check here in town for you tommrrow. A place here called Ra-Elco has a ton of high wattage resistors. That may have once been a common part bak in the days of vacuum tubes but you won't find it very common today.

Jon, I just checked the Digi Key catalog and you could series three 10 watt 25K resistors for 75K @ 30 watts.... Center part of the page, 89 series, of this link. They are 1% value and not too expensive, about 7 bucks each.
http://dkc3.digikey.com/PDF/T031/0723-0725.pdf
Mark @ CLACO

Posted by Jon Bartow (Member # 241) on 03-05-2003, 07:23 PM:

Mark, Yeah, I know I can do something like that if necessary, but just for kicks it would be nice to replace it with exactly the same part (it might be a pipe dream, but I can hope). Also, there isn't a whole lot of room in there for messing around with 900+ volts and a bunch of resistors.

J-Hawk, yes I did call them

Jonathan

Posted by Joe Morris (Member # 1553) on 03-05-2003, 11:07 PM:

can you take a picture of it so we can see it?

Posted by Jon Bartow (Member # 241) on 03-05-2003, 11:23 PM:

Ohmite 270 series
If Ohmite made a 20watt 75k version of this it would be exactly what I need . They do have 50 and 100watt versions but those are a bit too big

Posted by Darryl Spicer (Member # 711) on 03-05-2003, 11:37 PM:

what about the one they show on the chart that says L25 25watt with 0.15-100 ohms.

Posted by Sam Hunter (Member # 1119) on 03-05-2003, 11:39 PM:

Jon, this may be a longshot but check with some Motorola 2way shops and see if the have any of those Bleeder/Devider resiters left over. Seems to me they used that value or close to it in there old Tube BY stations.

Oh and check on the Newark Electronics website. They have almost anything you could want.

Posted by Jon Bartow (Member # 241) on 03-06-2003, 07:16 AM:

Thanks for all of the replies guys,

Daryl, The L25 resistors of the 270 series are not available in a 75k value (click on the link above and then click on "stock part numbers and availability")

Sam, Good idea, I'll try that. Newark doesn't have what I need, nor does Mouser, or Digi-Key. (see above posts)
Jonathan

Posted by Mark Gulbrandsen (Member # 72) on 03-06-2003, 08:41 AM:

Caddock doesmake a 75K 30 watt resistor FYI.
Mark @ CLACO

Posted by Ken Layton (Member # 133) on 03-06-2003, 08:52 AM:

Dale may also make one. Also try Antique Electronics (www.tubesandmore.com)

[ 03-06-2003, 03:43 PM: Message edited by: Ken Layton ]

Posted by Doug Eisemann (Member # 782) on 03-06-2003, 09:54 AM:

Hello. Here is a thread I can relate to since I restore old amps and I know what a pain it is to find certain parts. You could do a search on the web for a surplus electronics place in Texas called Nortex Electronics. I am not sure of the policy on this forum about posting links to commercial sites, so I won't add the link, but a search will turn it up.
They have the largest assortment of surplus electronic parts I have found, just email with what you need, and they probably will be able to help. Be patient, however, as it might take some time. I am sure there are sources for new resistors like you require out there, but they fail, check with Nortex.
Good Luck
Doug Eisemann

Posted by Darryl Spicer (Member # 711) on 03-06-2003, 11:45 AM:

It shows in the first chart an L25J75R as being available. Ooops never mind I was looking on the wrong chart. Yeah your right it does not show one.

Posted by Joe Morris (Member # 1553) on 03-06-2003, 12:42 PM:

What you have is actually a Clarostat. I have 32 of them running in my boorh. If you go to www.clarostat.com you should be able to find a dealer near you. That is why you are having such a hard time finding them. Everyone hears resistor and you get the little white blocks. Clarostats are the nice brown turd looking things.