April 11th 05, 02:28 AM
|
|
|
From: Telamon
Organization: Internet Argonaut
Newsgroups: rec.radio.shortwave
Date: Sun, 10 Apr 2005 18:58:57 GMT
Subject: Power Supples
In article ,
Greg wrote:
Okay, thanks to all who replied.
The people at
http://www.innovatronix.com/cgi-bin/...alog/index.asp
are marketing these power inverters to run studio strobes on location, which
implies, though they don't actually say so, that they run off a vehicle
battery and supply ample VDC for the studio strobes, which require recycling
large capacitors as rapidly as possible.
My interest would be in using an 12VAC inverter to supply 13VDC voltage for
my NRD-525, in hopes of eliminating power line noise (as well as powering
several potable, battery-operated radios). From what you guys are telling
me, either a linear or switching power supply would work, but filtering is
the critical factor. (This isn't a big priority - most noise at my location
is radiated noise.)
I'll sum up my previous response. Linear or switcher could work in
practice but it would be unlikely and expensive for a switcher supply to
not interfere with radio reception.
Not only do you need to use a linear supply but I would make sure that
supply is radio friendly. Just because it is a linear supply it does not
mean that the designer has gone through the trouble to provide an RF
bypass around the rectification diodes, which still create switching
noise even at lower voltages.
+++++++++++++++++++++++
You can find out if your reception noise floor is affected by EMI by
disconnecting the antenna and tuning slowly through all the bands you
want to listen too. This will allow you note down any birdies the radio
may have and at what level along with whether any conducted noise is
coming through the power cord.
You should terminate the antenna terminals 50 ohm input with a short
lead 50 ohm resistor in practice but it probably won't make a difference
in this test.
You can then reconnect the antenna and note the difference in noise. In
this way you can determine the difference in EMI and RFI at your
location instead of guessing.
--
Telamon
Ventura, California
Good advice. Thanks Teledude!
Greg
|