24 volt coil

Cacti_Ken · Posted: Sat Jul 10, 2010 8:58 pm Post subject: 24 volt coil

Wes, I have two used coils. On both, the primary resistance is 12.5 ohms.
The secondary resistance is 10.10K and 10.15K ohms.

Referencing to your photo of the coil on a previous post shows primary resistance of 5 to 6.2 ohms. And secondary 9k to 12k.

My coils secondary resistance are in the tolerance range of your test. But the primary is twice as high as yours.

Could I take it that these coils are bad? Its peculiar that both of the coils measure practically the same.

Ken
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Tropical Veteran
35th Inf. Reg. "CACTI" 4th I.D. VN
Amateur Radio K5XOM

wesk · Posted: Sat Jul 10, 2010 10:38 pm Post subject:

Ken,
What do your primaries ohm at when hot?
_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

Cacti_Ken · Posted: Sun Jul 11, 2010 12:34 pm Post subject:

I don't know Wes. I got the coils during my restoration and kept them for spares.

Is it ok to apply 24 volts to them for a short period maybe 15 to 20 seconds and check the resistance? Or best to put them in the distributor and run them assuming they are good to run.
_________________
Tropical Veteran
35th Inf. Reg. "CACTI" 4th I.D. VN
Amateur Radio K5XOM

wesk · Posted: Sun Jul 11, 2010 4:52 pm Post subject:

You just heat the coils with a hair dryer or heat gun until they just start to get uncomfortable to touch or hold. Then measure their resistance.
_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

maeserik · Posted: Tue Jul 13, 2010 4:49 am Post subject:

I have a spare 24 volt coil, i will measure the resistance this evening, i let you know.

Erik
_________________
1942 GPW 71336 my son's jeep restored now
1951 M38 MC11891
1953 VW beetle (genuine german Käfer )
1957 fantastic wife

http://www.surfacezero.com/g503/showgallery.php?cat=1865

and this webside

maeserik · Posted: Wed Jul 14, 2010 4:40 am Post subject:

I checked the coil, i have two M151 coils also 24 volt and same dimensions.

primary 12,8 ohm

secondary 12k ohm

cold measured on a spare one ( same as in use on my38 )

as info :
i use a mutt m151 coil in my distributor together with the swiss solid state ignition all on 24 volt
_________________
1942 GPW 71336 my son's jeep restored now
1951 M38 MC11891
1953 VW beetle (genuine german Käfer )
1957 fantastic wife

http://www.surfacezero.com/g503/showgallery.php?cat=1865

and this webside

Cacti_Ken · Posted: Wed Jul 14, 2010 4:34 pm Post subject:

I heated up the coils and the restistance only changed 3/10ths of an ohm.
Maybe different manufactures had different turns ratios in their coils

Ken
_________________
Tropical Veteran
35th Inf. Reg. "CACTI" 4th I.D. VN
Amateur Radio K5XOM

Wiltshireboy · Posted: Fri Jul 16, 2010 1:09 am Post subject:

Does anyone know what amount of change of resistance on the primary and secondary windings from cold to hot indicates that the coil is not good?
_________________
Andy
M38A1 & M416A1 trailer


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