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From: James Maynard (no email)
Date: Tue Aug 10 2004 - 19:55:52 EDT
I didn't pick up a 120 Vac radio. The noise on the 120 Vac line will
radiate throughout the boat and affect radios that get their power from
12 Vdc.
If you install an inverter, and especially one with sharp edges to its
waveform, you also should monitor for EMI (electromagnetic interference)
and be prepared to suppress it -- just as when you install a fluorescent
light or a wind generator.
The higher the frequency band on which you receive, the less your
reception will be affected by noise from other devices on the boat. And
the lower the frequency band, the more it will be affected by that
noise. (It has to do with the Fourier transform of the waveform --
higher frequencies have less amplitude.) Which is why loran receivers
are so fussy about EMI (they operate well below the AM broadcast band,
at 100 kHz) and VHF radios are much less so. For the HF ("high
frequency") bands between 3 MHz and 30 MHz, where we like to listen to
distant stations that we receive by "sky waves," we are generally
listening to weak signals, so it's that much more important to suppress
the radio frequency noise sources on your boat.
-------------------------------------
Jim Maynard ()
Salem, OR 97302, USA
-------------------------------------
-----Original Message-----
From: Pilgrim [mailto:]
Sent: 10 August 2004 15:12
To:
Cc:
Subject: Re: lv-ab: Inverters... pure sine or modified?
James Maynard wrote:
> If you are ever going to have a short-wave radio on board -- receiver
> or transmitter -- then it would be better, I think, to go with a pure
> sine wave. The "sharp edges" of the "modified" sine wave create
> harmonics (multiples of the fundamental power frequency) which may
> interfere with short wave reception, occurring as they do every 50 Hz
> or 60 Hz (depending on whether your inverter puts out 50 Hz or 60 Hz
> "modified sine wave").
>
Good advise .. but where did you pick up a 120 volt radio? Most if not
all SW/SSB/Ham units are 12 volt only.
-- Brian Stewart Pilgrim Whitby 42 #304 VB8320 VA3PIL ___________________________________________________________________________ || The Live-Aboard List : send a "subscribe" or "unsubscribe" request || || in body of message to: ||
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