What Rich says is plenty good enough. But if you don't want to change
anything, there's another trick. When I was in a condo, I found that there
were two 120 VAC outlets on different phases in relatively close proximity.
I simply made up two extension cords, one from each outlet, and ran them
into a box in which I mounted the appropriate 240 VAC outlet. Each of the
"hot" (black) sides went to each side of the 240 VAC outlet, and, since I
had no need for 120 VAC from this system, I used the grounds as the 3rd
prong. The neutrals were simply not connected to anything. Worked great,
still had circuit protection appropriate for the wiring, and made no
permanent changes to anything. My Dad currently uses this for 240 VAC in
his shack, as there is no other source for it.
Yes, I'll probably burn in NEC hell for this, but... Eh.
Kim Elmore, N5OP
At 04:57 AM 12/3/2004, you wrote:
On Dec 2, 2004, at 5:20 PM, Martin J. Morgenbesser wrote:
I'm thinking of acquiring an SB-200 or SB-1000.
While I realize that it's preferable to power the SB-200 and SB-1000 amps
from a 220 Volt AC line, I don't currently have 220 service in my shack.
What I do have is a 110 Volt 15 Amp line.
Martin -- Converting a 3-wire 15A, 120v circuit to 15A, 240v is not
difficult if you have an unfilled circuit breaker slot available in your
breaker box. To do this mod, switch the mains off, change the 3-wire 120v
outlets on this circuit to 3-wire 240v outlets, wrap red electrical tape
around the white wire to indicate that it is not a N wire, connect the
extant black wire and white/red wire to the L1 and L2 connections on the
240v outlets, wire the ground wire to N/gnd on the 240v outlets, remove
the single 15A CB, wrap red electrical tape around the white wire to
indicate that it is not a N wire, and install a dual 15A CB. Wire the
output of the dual-CB to the black and white/red wires. If you desire to
have 120v outlets on the same circuit, connect the ground wire to both N
and gnd on the 120v outlets and connect the L to either the black or the
white/red wire. ///
There are a number of electrical experts who will tell you that this
arrangement is strictly immoral, unpatriotic, against the National
Electrical Code, that it is not safe, and that it's sinful in the eyes of
the Almighty - - but I have been using this arrangement since 1975 without
a problem.
-- note: this configuration will not work with ground-fault-interrupter
circuit-breakers, but since they tend to interrupt in RF fields, for a
Ham-shack they are not satisfactory.
My transceiver, lights and laptop together draw maybe 5 amps from the
line, so I wouldn't want the amp to draw more than 7 or 8 amps.
In your experience with these amps, how much RF power out can I run them
at while keeping the amplifier's 110 volt AC line current draw below 8 amps?
It's different for different modes.
Eventually, I'll probably install 220 service in the shack, but I want to
know if I can use these amps in the interim with only a 110 volt AC line.
Perhaps I should be looking at the Ameritron AL-811 amps which are rated
at 8 amps of AC line current draw for 110 volt service?
The best amplifiers for 120v operation are the old Henry Radio amplifiers
with a resonant-choke HV power supply. The reason for this is that a
resonant choke PS puts about 1/10 of the peak current demand on the mains
as an equivalent C-filter power supply.
Your thoughts and suggestions will be greatly appreciated.
73 de W7MJM
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Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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Kim Elmore, Ph.D.
University of Oklahoma
Cooperative Institute for Mesoscale Meteorological Studies
"All of weather is divided into three parts: Yes, No, and Maybe. The
greatest of these is Maybe" The original Latin appears to be garbled.
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