Calculating Choke Current Rating

[tekuhn]

Hello - I have a few large (physically) chokes salvaged from a power supply. I'd like to use them for a project but I'm not sure how much current they would be rated for. I have a BK Precision LCR meter and they measure about 5.75H @ 120Hz. The DCR is 145Ω. I wrote on them 162ma, but have no idea where I came up with that number. Referencing Hammond catalog, these have a fairly high DCR for the inductance so I'm not sure. I probably need realistically about 100ma max through them, but realize if I try to draw more than they are rated for, they saturate and stop working.

 

[Mr Boochie]

You need an inductor tester. There are DIY ones.

 

[nerdorama]

The only way I know to do it is by comparison to other chokes of approx the same physical size along with inductance and resistance values. Several of the Heathkit W series amps have the same choke which is rated at 7H, 160-170 ohms and 150-160mA. These values varied a bit in the schematics but they all have the same Heathkit p/n on them.

You could probably rig up a test with a current source and watch the inductance value until you see saturation.

 

[tekuhn]

That's what I'm doing - Hammond has a 6H that's 150Ω DCR and it's rated for 200mA. I think the 162mA that I labeled on them is probably right, but I can't find any data on this specific part number so I'm not sure where I came up with it. Pretty sure it's military surplus - #CRV 30829. Really nice - potted in cylindrical flanged body that's soldered closed. Ceramic insulators where the leads exit. I suspect it's rated for very high voltage. There's one on eBay right now and seller claims it's made by RCA for military WWII.

 

[Mr Boochie]

That's what I'm doing - Hammond has a 6H that's 150Ω DCR and it's rated for 200mA. I think the 162mA that I labeled on them is probably right, but I can't find any data on this specific part number so I'm not sure where I came up with it. Pretty sure it's military surplus - #CRV 30829. Really nice - potted in cylindrical flanged body that's soldered closed. Ceramic insulators where the leads exit. I suspect it's rated for very high voltage.

Does it look like the Hammond 159R? Dimension-wire?

 

[tekuhn]

Not sure. Here it is next to the 7H Heath that Nerdorama referenced.......

 

[Mr Boochie]

Not sure. Here it is next to the 7H Heath that Nerdorama referenced.......

You really need to be able to see some of the laminations and windings.

 

[trobbins]

Comparison of inductance to commercial chokes preferably needs the Vac applied to the choke to be circa 5-20Vac, and the dc current increased to indicate any inductance droop. As indicated, comparison of DCR and dc current and commercial chokes of similar physical size, is the other factor to assess, as it compares internal dissipation W, and hence an indicator of internal temperature rise.

Link to a diy method I use for chokes. https://www.dalmura.com.au/static/Choke measurement.pdf

 

[tekuhn]

I kept searching online and finally found the federal part number and technical data for it. It was made by RCA for Lockheed Martin. Apparently I had located this years ago when I labeled them, because 162mA is correct. There is no DC voltage rating, but they will see under 400vdc max. Thanks everyone for the help!

Technical Data | NSN 5950-00-147-1487

Characteristic	Specifications
TERMINAL TYPE AND QUANTITY	2 STANDOFF, SOLDER LUG
RATING METHOD	ELECTRICAL SINGLE COMPONENT SINGLE WINDING
WINDING OPERATING CURRENT	162.0 MILLIAMPERES DC MAXIMUM SINGLE COMPONENT SINGLE WINDING
DC RESISTANCE RATING IN OHMS	160.000 SINGLE COMPONENT SINGLE WINDING
INDUCTANCE RATING	4.50 HENRY NOMINAL SINGLE COMPONENT SINGLE WINDING
WINDING QUANTITY	1 SINGLE COMPONENT
INDUCTANCE TYPE	FIXED
MOUNTING METHOD	FLANGE AND UNTHREADED HOLE SINGLE GROUP
MOUNTING FACILITY QUANTITY	4 SINGLE GROUP
CENTER TO CENTER DISTANCE BETWEEN MOUNTING FACILITIES PARALLEL TO LENGTH	2.437 INCHES NOMINAL SINGLE MOUNTING FACILITY SINGLE CENTER GROUP
CENTER TO CENTER DISTANCE BETWEEN MOUNTING FACILITIES PARALLEL TO WIDTH	2.437 INCHES NOMINAL SINGLE MOUNTING FACILITY SINGLE CENTER GROUP
INCLOSURE TYPE	FULLY INCLOSED
BODY LENGTH	3.250 INCHES NOMINAL
BODY OUTSIDE DIAMETER	2.625 INCHES NOMINAL
RELIABILITY INDICATOR	NOT ESTABLISHED

Cross Reference | NSN 5950-00-147-1487

Part Number	Cage Code	Manufacturer
K901340SUB1GP501	21921	RCA CORP DISTRIBUTOR AND SPECIAL PRODUCTS DIV
K901340SUB1GP501	49671	LOCKHEED MARTIN CORP LOCKHEED MARTIN INFORMATION SYSTEMS

 

[tekuhn]

These will be used in a CLC Pi filter and only have to handle the current of one channel of an ST-35.