Tnx Jim for the info. The cheap thing would not be to go to a larger
generator. This is a 16KW unit.
From: Jim Lux [mailto:email@example.com]
Sent: Friday, August 25, 2006 4:41 PM
To: N2TK, Tony; 'WA3GIN @ Arlington County, VA'
Cc: 'towertalk reflector'; 'Doug Rehman'
Subject: RE: [TowerTalk] OT: Generators and UPS's
At 01:19 PM 8/25/2006, N2TK, Tony wrote:
>Any thoughts about using something like a Tripp Lite IS1000 isolation
>transformer to help this? Was thinking of getting one and plug in my rig,
Nope.. a transformer doesn't help the waveform. A big ol' honkin' 60 Hz
bandpass or low pass filter maybe? Or, loads that have better current
waveforms (i.e. they look more like a resistor, rather than a diode feeding
There are solid state PFC and harmonic content devices made that
essentially turn a very spiky current draw into something smooth and
sinusoidal. I've only seen them as modules for the front end of switching
power supplies (e.g. from Vicor), but I imagine that someone makes them for
generalized AC in to AC out kinds of applications. Think of them as an
active bandpass filter for 60 Hz.
But pretty soon, you run into a cost effectiveness problem. It might just
be easier and cheaper to use a bigger generator (so that the series
impedance is lower, so the current ripple results in a smaller voltage
ripple) as 'GIN suggests.
OTOH, hams are great scroungers... maybe a LC filter tuned to 60 Hz would
do the trick. Surplus PFC or motor run capacitors are available. Scrounge
a big transformer core (microwave ovens are a good source, these days) and
wind your inductor. 100 uF and 70 mH will resonate at 60Hz. Actually,
probably a low pass filter with a cutoff of, say, a few kHz might be all
you need (depends on how picky the UPS is... and, the filter only has to
carry the UPS current, not the full load current of the generator)
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