>As a new-comer to this list (which surprisingly seems to be as much a
>battleground for amp ideas),
Not much battling. Some ideas are supported by the laws of physics and
by evidence, however, some ideas are not. Eventually the sea stories get
sorted out.
> I would like to know more about the
>"Glitch" resistor...
... is not a fuse. Its purpose is limit peak fault current (to <200a or
so in sb220s and the like). To test a glitch resistor, short the anode
supply to ground with a long screwdriver. If the glitch resistor is not
damaged, and the measured R not change, it's a winner.
>I have heard various responses (read seen),... from
>10 ohm Glass encased r's to Nichchrome wire to 1 amp 250v 3AG fuses...
>In my single 4cx250 432 amp I have a 500ma 250V
Using a 250v fuse in a 2200v circuit is not good engineering practice.
When this fuse attempts to open, a metal vapour arc (with about 15v drop)
forms in the fuse, which does not limit current until the fuse eventually
explodes.
... ...
>I use an un-modified SB-220 which has 1970's
>vintage 3-500's and do occasionally get an arc... I have heard this
>described as anything from VHF parasitics
Stock sb220s sometimes oscillate at c. 110MHz. If you have a vhf field
strength meter, it might be fun to set it next to the sb220.
- There is an article on vhf parasites in the 9/90 *QST* magazine. The
photo on p.15 of the kaput 3-500Z innards might be of interest. Each
time a tune cap. has a parasitic-arc, the hot filament is subjected to
lateral emf, which incrementally bends the filament. Eventually, a
grid/filament short occurs - usually when the filament is at operating
temperature.
Rich...
R. L. Measures, 805-386-3734, AG6K
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