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

[Rob Atkinson]

I forgot to mention that in the previously mentioned wiring I
described, the power cord was two hots and ground.  Ground line simply
comes in to the cabinet and is bolted to it, so the rig with the fake
CT neutral, is essentially running on two hots.

The 3-400 rig here was originally set up like the BC1T but I didn't
like that since it was a homebrew rig with a lot of different 120 v.
loads:  Modulator, driver, fan and filaments all ran on 120; only the
RF final B+ supply ran on both hots.  I separated ground and neutral
in the rig and set up 4 wire service, installed a 4 wire power cord
and outlet and now it has a separate ground and neutral return and I
think it is less flaky unless it is just my imagination.

the 3-400s have to have forced air and they are in chimneys and I put
in a Dayton blower that runs off 240 and moves twice as much air but
since the rig is around 10 or 15 feet away from me I can't really hear
the blower noise.

73

Rob
K5UJ

On Sat, Oct 17, 2015 at 7:19 PM, Donald Chester <k4kyv at hotmail.com> wrote:

>
> 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.
>