>Would someone be kind enough provide me with a source for a replacment 1mh
>RF choke for the grid of a SB-220. The only values I am able to locate
>are Millen 200 and 300 ma 1mh chokes. What value should I look for as a
>replacement?
>
1mH chokes make lousy fuses because they are too difficult to burn out.
Unless you have a free supply of new tubes, the 1mH chokes should be
replaced with something that limits grid current to a safe value. A
0.25A fast acting fuse is a good choice. Or, a 30-ohm 1/4 or 1/8 watt
carbon film resistor will protect the tube from shorts. In order to
prevent opening of the fusing device during 10m operation, the grid
bypass needs to be increased from 600pF to 1500 - 2000 pF total.
note - If you continue to blow grid fuses, perhaps lower Rp parasitic
suppressors are needed.?
cheers, Richard
- Rich..., 805.386.3734, www.vcnet.com/measures.
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