TS-830S mobile ops

Steve Harrison ko0u at OS.COM
Tue Jul 13 18:15:50 EDT 1999

At 01:58 PM 1999-07-13 -0700, Lane Zeitler wrote:
>I need to find a nice 12vdc to 120vac converter that will allow me to run
>the best rig ever made, my old Knwd TS-830S, mobile. I have been looking at
>the Astron converters but have not found anyone at all that has used them.
>Is anyone familiar with the Astron 120vac power converters? Any other brands
>out there?

Go to your local big-time discount store, like Wal-Mart or preferably, a
discount club. Maybe even Home Depot, for that matter. Most of these places
may have these 700 watt 12VDC-120VAC inverters available for about $99.95.
Tech-America probably has something like these. Some places may only have
the lower-power units like 170 watts, 300 watts, etc. In that case, most
will be glad to order a larger one for you; or you can look on the boxes
and get the manufacturer's phone number and call em. Even RS may have them
by now. Last resort: go to, or call, a trailer or mobile home supplier.

Of course, every one of these things puts out what they call a "modified"
sine wave, which means it's basically a square wave with rounded edges but
still basically a flat or undulating top. There may also be some spikes.
You would want to load the thing with a nice load and look at it with your
scope. And the waveform may be different with an inductive load such as a
transformer. It may even change shape between high and low loading, such as
transmit and receive. Usually, you won't have a problem; but your
transformer COULD run extra hot on such a waveform, and your B+ just might
have high spikes that could pop electrolytics, etc.

The art of making high-power, low-frequency sine waves still lives on at
Border Dam and other such places, but otherwise seems to be lost.

There's other ways, too: a time-honored favorite was to connect three
matched 12V filament transformers across an alternator's stator windings
and parallel the outputs, I think. Or maybe the outputs were series, I
don't remember now. You got high frequency, like 300-500 Hz, but most
ordinary power transformers would handle it just fine.

73, Steve K0XP

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