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Thursday, December 29, 2011

New plate chokes from Lundahl


Lundahl came out with a new plate choke, the LL2743. It is wound on a larger core size as the existing range of LL1667 and LL1668 plate chokes. They come on the same core as the LL1673. This allows higher current chokes for use in the output stages of parafeed amps.

The choke can be ordered with different air gaps for various DC currents. The photo above shows three versions: 50Hy/90mA, 65Hy/70mA and 90Hy/50mA. Like all Lundahl chokes they are wound with two separate coils which can be connected in series or in parallel. The inductance and current values are given for the series connection. Parallel connection will result in one quarter of the inductance at twice the current. This is because inductance has a square relationship to the number of windings. Doubling the windings results in 4 times the inductance. The DC resistance of the choke is 200 Ohm per coil.

The next photo shows the LL2743 in comparison to a LL1668:

The LL2743 complements the LL1667/8 very well, extending the current range of the plate chokes up to 100ma. Of course these chokes can also be used for B+ smoothing if you don't mind the higher DC resistance.

Best regards


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