118H shadowmeter resistance - Printable Version

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+--- Thread: 118H shadowmeter resistance (/showthread.php?tid=4811)

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118H shadowmeter resistance - Glenn Roberts - 05-27-2012

Ok I finally got around to winding the shadowmeter coil and I can't remember and can't find what the heck the resistance is supposed to be. I think it was around 1000 Ohms, but want to be sure. Can someone please confirm this? If it is I need to pull off some wire..I'm at 1900..oops. Thanks for your help.

Glenn

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RE: 118H shadowmeter resistance - Radioroslyn - 05-28-2012

Should be about 1.1K.
Terry

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RE: 118H shadowmeter resistance - Glenn Roberts - 05-28-2012

Terry,
Thanks for the confirmation. Now the bad part unwinding 800 ft of 40 ga. oh well.

Glenn

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RE: 118H shadowmeter resistance - morzh - 05-28-2012

I just wonder how 1K can become 1.9K, if it is wirewound. Or have I not understood?

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RE: 118H shadowmeter resistance - Radioroslyn - 05-28-2012

If it is a real hassle you could just add a resistor across the coil to lessen it's sensitivity.
Terry

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RE: 118H shadowmeter resistance - Glenn Roberts - 05-28-2012

When I was winding it I was thinking "I don't think this much came off this spool, but if I'm short I really don't want to start over" I was shocked when I took a reading and it was a little over 1.9k.
Taking it off won't be too bad just want to wind it on something to save it for another project. I found a little 100 rpm gear motor that has the perfect shaft size for the coil "bobbin". What a monotonous job.

Morzh,
it's not "wirewound" as in a resistor, it is the wire wound coil for the shadow meter vane.
Here is a picture of the coil and shadow meter assembly from Chuck's website.
http://www.philcorepairbench.com/images/smrepair04.jpg

Glenn

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RE: 118H shadowmeter resistance - Glenn Roberts - 06-01-2012

   

Success!!

Question, as usual, the original was sealed in a stiff paper wrap and wax. Should I seal this in hot glue, clear nail polish...?? any other suggestions.

Thanks,
Glenn

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RE: 118H shadowmeter resistance - Radioroslyn - 06-01-2012

Nail polish has some nasty solvents in it I'd go with the hot glue or candle wax.
Terry

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