[Boatanchors] 240VAC appliances and a need for the neutral‏

[Donald Chester]

> I've seen ham gear running off 240 v. with h.v. supply that has a 240
> v. CT primary and 120 v. loads like cooling fans running off one leg
> with return connected to the h.v. supply transformer CT as a fake
> neutral.
 
> 73  Rob K5UJ
 
The Gates BC1-T broadcast transmitter has the neutral strapped solidly to 
the cabinet and ground (a violation of current NEC).  For low power 
(250w) mode, they feed the plate transformer off one leg and neutral.  
The 833A filament transformer has a midtapped primary, designed to 
create the fake neutral to allow a small amount of current at 120v for 
accessories to the transmitter, but I doubt it  would be good for more 
than a couple of amps.  When I modified mine for amateur use, I 
disconnected the strap between neutral and cabinet ground, leaving the 
neutral floating, and ran a separate hard ground to the a.c. mains 
safety ground plus an 8' ground rod just outside the shack.
 
The fans have 120v  motors, but Gates wired them in series to run off 240.  
They are far too noisy when using the transmitter in the same room with 
the microphone, so I run mine off one leg with return to neutral, so 
each motor is running off 60v.  They run OK at reduced voltage, much 
quieter, but still move enough air to keep the 833As cool. In fact, I 
have a switch on the front panel to turn the fans on and off.  The only 
time I use the fans is when I try to run the transmitter in  summer when
the ambient temperature is above 80 degrees or so.  In winter I keep 
the shack at about 60 degrees and don't even bother to run the fans. 
Since it is a dedicated 160m transmitter, I rarely use it in summer.
 
 
Don k4kyv