Mike and Doc,
I agree that factory radios are actually very good sets (possible exception
being the very bottom end units). In 1999, I spent more than a month at a
factory where auto radios were the main production item. (My company was
providing an EMC test chamber to the radio manufacturing company and I was
responsible for system integration.) I can tell you that the factory
radios get extensive EMI/EMC testing. I have to presume that they contain
components to resolve RFI issues - I never saw any schematics while I was
there. However, hard to pass the tests if the units aren't designed right.
Back in the days when car radios where more option than standard issue, a
car radio cost a fair number of bucks compared to what you could find at
the local department or appliance store. Performance costs - and in car
radios, they don't have to make anything other than the front panel look
nice. Sure, aftermarket sets generally cost less than the factory radio,
but it is probably a fair guess that you are getting a lot less. These
radios seem to emphasize gadgets and lots of audio power output. I'll bet
it's a real "blast" when a 500 watt car stereo is in a vehicle that is
passing an 18 wheeler and the trucker signs with "10-4, Good Buddy" while
running his 500 watt "flamethrower".
One of my favorite customer calls was from an engineer at a car radio (OEM)
manufacturer. He said that his new radio design worked fine until the
clock for the microprocessor was activated. My EMC advice to him was
"leave out the clock". He had a poor sense of humor.
Incidentally, despite what the faceplate of your car's radio says for a
brand name ("Ford", "Chrysler", "Saturn", etc.), there is a pretty good
chance that the car maker did not make that radio. The factory in which I
spent several weeks working was owned by a non-automotive manufacturer and
cranked out radios for at least three different major car names.
73, Dale
WA9ENA
"Michael Tope"
<W4EF@dellroy.com To: <kd4e@arrl.net>,
<rfi@contesting.com>
> cc:
Sent by: Subject: Re: [RFI] BPL Protest
Opportunity? & BC-AM Ant Improvement?
rfi-bounces@conte
sting.com
05/05/2004 04:37
AM
> More directly on-Topic for this RFI list, anyone
> know of an add-on BC-AM preamp for the car? Or
> a source for a better antenna (no room inside the
> fender of my Chevy Astro van for a power antenna
> with a long telescoping whip) -- perhaps a longer
> fixed whip or a coil base that would electrically
> lengthen the antenna without making it absurdly
> tall?
>
> I am told that BC-AM tuner sections are junk in
> all of the new radios and with the coming of
> digital BC-AM there is no incentive to upgrade
> the old analog technology. Meanwhile I'd sure
> like to strengthen the initially captured signal
> so the engine and environmental noise doesn't
> drown-out the weak ones!
>
> Off to work ...
>
> --
> Thanks! & 73, doc kd4e
> West Central Florida
I have always found factory radios (at least Fords)
to have pretty good AM receivers. Most aftermarket
car stereos seem to be absolutely awful, however.
If your engine noise is radiated as opposed to
conducted into your car radio, then using a
preamplifier probably won't improve the
signal-to-noise ratio because the noise will get
amplified just as much as the signal. If the
noise is conducted you may be able to
filter the power leads going into your radio.
I haven't looked into aftermarket BC band
antennas, so I can't really offer anything
valuable in that regard.
73 de Mike, W4EF..................................
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