Pete Smith wrote:
>Before I mail order some copper flashing or go to one of the lightning
>protection outfits for far more than I'll need, is there any non-radio
>source of appropriate stuff for grounding my SB-220 grids? I think
>that stained glass makers use copper foil strips, but assume that is
>probably too thin for what I need.
It's certainly thick enough to carry the RF current. Thanks to the skin
effect, even very thin copper foil in a 5mm (3/16in) width will carry
1500W at HF without getting warm (that's 5.5A into 50 ohms).
If it's also wide enough to provide a good low-inductance ground
connection, it will handle any DC current as well - up to and including
the large current surge from a you-know-what :-)
As part of the general upgrade, also consider installing:
* A 30-ohm 25W glitch resistor in the B+ line (choose a long, thin
vitreous wirewound resistor to handle any high voltages)
* A step-start circuit, because it allows you to change the mains fuse
to a fast, low-rated type that will protect the whole amplifier better.
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
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