[Boatanchors] Line Voltage issues

[Richard Knoppow]

----- Original Message ----- 
From: "Robert Spooner" <rls19 at psu.edu>
To: "Richard Knoppow" <1oldlens1 at ix.netcom.com>
Cc: "Bill W7KXB" <w7kxb at msn.com>; 
<boatanchors at mailman.qth.net>
Sent: Tuesday, January 06, 2015 2:40 PM
Subject: Re: [Boatanchors] Line Voltage issues


The problem with autotransformers such as the Variac is that 
they are high enough impedance that you may see inordinate 
voltage fluctuation with changes in load unless the current 
rating is high relative to the current draw. My favorite 
solution is to use a filament transformer to buck the higher 
voltage down to the rated voltage for the equipment. As long 
as the secondary current rating is equal to or greater than 
the maximum AC current draw, the transformer will be 
adequate for the job.

73,
Bob AD3K

    This is always the problem with a regulator, does it 
regulate the load side or the supply side?  Some do both. I 
think the electronically controlled Variac regulators will 
do both since they sense the voltage on the load side.  A 
constant voltage transformer will also regulate both sides 
within some limits. A fixed transformer such as either a 
Variac or a bucking transformer does not regulate. The same 
consideration of internal impedance must be given to any 
transformer since high impedance will cause a voltage change 
with load change. I am not sure of how much of the total 
current goes through a bucking transformer, perhaps it 
depends on how its connected.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com