[Milsurplus] Triad Choke

[Military1944 at aol.com]

de WB2CPN
Would whoever sent the info about the
choke resistance  and inductance being
used to indicate the wire size and max
current please  send it to me.   I lost it here.
Trivia, but we called those chokes  which
would normally saturate under high current
"Swinging Chokes".   For better regulation.
Thanks Much.
73  Clete



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this was in the archives Clete. Might be what you were after?  Ben.
 

I don't have Triad information, but dc resistance gives a good clue

about current rating.  From UTC Commercial Grade:



75 Hy 50 ma 2200 Ohms

30 Hy 100 ma 400 Ohms

10 Hy 200 ma 110 Ohms

12 Hy 150 ma 110 Ohms

12 Hy 250 MA 100 Ohms

10 Hy 350 ma 90 Ohms

10 Hy 500 ma 52 Ohms

10 Hy 1000 ma 40 Ohms.



FYI

Richard, AA1P
 
More:  Measuring a power filter choke on an inductance meter is not

useful because the inductance goes down substantially when dc passes

through, as in service.



Measuring choke characteristics is easily done.  Use most any power

transformer with full wave rectification and no filtering.  Connect the

test choke in series with a resistor R of several thousand Ohms, and a

milliammeter from + to the transformer center tap.  Varying input

voltage, measure ac voltage across the choke, and resistor, and dc

current.  Then:



L = (Echoke x R) / (Eresistor x 2 x pi x f)



For 60 cycle input with full-wave rectification, 2 pi f becomes 2 x 3.14

x 120, or 754  

Now L = (Echoke x R) / (Eresistor x 754)



Measure ac voltage with an average reading (VOM) meter.  Use a blocking

capacitor to keep dc off the meter.



As you increase the current you will see the voltage increase levelling

off, indicating you are getting into saturation, and is approximately

the useful current limit.



References:

"Measuring Inductance of DC Loaded Chokes," J. H. Ellison, W6AOI, QST,

Feb. 1963 pp16, 17.

"Know Your Filter Choke Coils," Harold Reed, W3EJP, CQ, Nov. 1959, pp

50, 51.



Richard, AA1P