K3HVG wrote:
I'll second that. Both my NC-183,183D, and various other vintage rigs
ran very hot at my nominal line voltage, here, of about 120-125 volts. I
now use a Variac in power distribution line for the older radios and set
it at 110v. The drop in temp of the transformers was dramatic....
There may, of course, be other problems like leaky caps, etc. so a
complete check may be necessary. de K3HVG


One trick you can use to achieve 110V from a 120V nominal power line is
to take a 12.6V filament transformer with a secondary current rating that is
greater than the current drawn by the load, and hook it up as a series
bucking auto transformer... The primary goes across the 120V power line,
and the secondary is in series between the power line, and the radio to
be powered. Pick the 12.6V secondary's polarity so that the voltage drops,
rather than raises. If 12.6V is too much of a drop for your situation, you
can always use a 6.3V transformer to get 115 to 117V.

Much cheaper than a variac.

-Chuck

"Chuck Harris" wrote in message
...
K3HVG wrote:
I'll second that. Both my NC-183,183D, and various other vintage rigs
ran very hot at my nominal line voltage, here, of about 120-125 volts. I
now use a Variac in power distribution line for the older radios and set
it at 110v. The drop in temp of the transformers was dramatic.... There
may, of course, be other problems like leaky caps, etc. so a complete
check may be necessary. de K3HVG


One trick you can use to achieve 110V from a 120V nominal power line is
to take a 12.6V filament transformer with a secondary current rating that
is
greater than the current drawn by the load, and hook it up as a series
bucking auto transformer... The primary goes across the 120V power line,
and the secondary is in series between the power line, and the radio to
be powered. Pick the 12.6V secondary's polarity so that the voltage
drops,
rather than raises. If 12.6V is too much of a drop for your situation,
you
can always use a 6.3V transformer to get 115 to 117V.

Much cheaper than a variac.

-Chuck

Another trick that works well on smaller transformer-powered
receivers is adding wire wound power resistor in series with
the transformer primary winding. I use Dale chassis-mount
30-ohm resistors (the style with tabbed aluminum shells)
for a lot of early Zenith restorations.. Often the filament
voltages are pushing 7 volts, and the transformers running so
hot you can't touch them--and that's after replacing all caps.

Pete k1zjh