I am doing my annual shack cleaning and I have a used National MB-40-SL Multiband Tank Assembly. I believe it can be used in push-pull and single-ended output tank circuit designs, with an output of 40 watts or less. It can also be used in the grid input stage when the drive/input power is 40 watts or less. It has a swinging link coupling coil. I think it is best suited for use as the tuned input tank circuit for a high-power common-cathode linear or class C amplifier.
I removed this a number of years ago from a homebrew linear amplifier that ran a pair of 811As in common cathode in the output stage. It was used in the input/grid circuit.
Unfortunately, I have no other technical information available pertaining to this unit.
The price is $35.00, plus the cost of shipping to your QTH.
Please contact me at
triodes@optonline.netThanks & 73,
Bruce, W2XR