This is an old trick that I learned many years ago. By taking a
transformer, driving its primary from the mains and then feeding that
transformer's secondary voltage in series (either in phase or out of
phase) will either add (in phase) voltage to the transformer primary,
or subtract (out of phase) voltage to the transformer thereby
reducing the transformer's primary voltage by the amount of the
buck/boost transformers secondary voltage. It's important to use a
transformer for the buck or boost circuit that can handle the amps
necessary for the particular load.
I often used "Healthy" filament transformers to do the job.For
example... At one time I had a Kenwood 820S transceiver that I picked
up in Japan. Japan's mains voltage was 100 VAC. When I got back
home I needed to get the 120 VAC stepped down to 100 VAC to properly
run this rig. What I did was to take a Triad multi-voltage
"Dry-Disk" transformer and connect the primary winding across the 120
VAC mains. In this case I used the 18 VAC secondary windings and put
that in series but out of phase, with the Kenwood Radio's
primary. This reduced the 120 VAC going into the Kenwood to about
102 VAC (120V-18V=102 Volts). Had I connected the Dry-Disk
transformer's winding in series and in phase I would've had 138 volts.
I hope this helps.
Burt, K6OQK
Subject: Re: [time-nuts] HP 5370B dropping mains voltage
How Does that Work Robert?
I mean why out of phase?
-----Original Message-----
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com]
On Behalf Of Robert Atkinson
Subject: Re: [time-nuts] HP 5370B dropping mains voltage
Hi Marki,
Dropping the mains voltage is easy. Get a mains to low voltage
transformer. Connect the primary across the mains and the secondary
in series opposition (out of phase) with the mains supply. Foar
example a 100VA 12V transformer will drop your mains to just under
238V with a maximum load of 8A (the current rating of the secondary).
HTH,
Robert G8RPI.
Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California U.S.A.
b...@att.net
www.biwa.cc
K6OQK
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