Greetings to all,
I normally stay out these nonsensical discussions, but just could
not let this one pass. From my perspective, there is just nothing in the
Ham Shack that is simpler than it's AC wiring. The one that got me was the
statement that 220 AC wiring should be larger than 110 AC wiring. Come on,
people!!
An SB-220 draws basically the same power from the AC mains when
powered by either 110 AC or 220 AC. The only real consideration is whether
your Ham Shack's (household wiring) 110 AC wiring can pass the required
current to the amp with an acceptable voltage drop. My Ham Shack wiring is
all done with #10 wire. I regularly run BC-610's, T-368's, and Johnson Desk
KW's from 110 VAC and have never, in 48 years as a Ham, had a problem with
my AC wiring. While I am not suggesting that you do it, small amps like
the SB-220 simply do not present a problem when operated from an adequately
designed 110 AC system. Now, if your Ham Shack's 110 AC wiring is done with
#14 wire, as many are today, you have a completely different situation.
However, a 220 AC circuit wired with #14 wire should be more than adequate
to power an SB-220 (again, I am not suggesting that you do this).
Here is a question for the group. In the SB-220 linear (as well as
many others) why are the circuit breakers (fuses) not changed when switching
from 110 VAC to 220 VAC operation? This is a very simple point but is
really misunderstood by many Hams. Heath even supplied a series of
incorrect schematics with the SB-220 several years ago. After several
letters, back and forth, they changed their schematics back to the original.
I have all three sets of these SB-220 schematics just in case some Doubting
Thomas dose not believe this. It all depends upon where the CB/fuse is
placed in the wiring. If the CB/fuse is placed in the AC main (inside the
set) it must be changed when changing input voltages. However, if the
CB/fuse is placed in the leads to the individual transformer windings, as
HeathKit did, they need not be changed because each winding in the
transformer only sees 110 VAC no matter whether the set is powered by 110
VAC or 220 VAC. No, I am not trying to re-invent Ohms Law, this is simply
how the circuit works, and it works great.
73 de K5JV
Lon W. Cottingham
1110 Golden Bear Ln.
Kingwood, TX 77339
281-358-4207
281-358-4234 FAX
281-795-1335 CELL
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