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From: larry@kitty.UUCP (Larry Lippman)
Newsgroups: net.analog
Subject: Re: Does anybody know why Auto AM radios tune with variable inductors?
Message-ID: <703@kitty.UUCP>
Date: Mon, 13-Jan-86 08:47:18 EST
Article-I.D.: kitty.703
Posted: Mon Jan 13 08:47:18 1986
Date-Received: Sat, 18-Jan-86 07:14:04 EST
References: <2859@watvlsi.UUCP>
Distribution: net
Organization: Recognition Research Corp., Clarence, NY
Lines: 19

> I have found that 99% of auto AM radios use a bank of variable
> inductors for tuning; whereas all other portable AM's use
> variable capacitors.  Anybody out there know why?  My only
> guess is that the variable capacitors might not be rugged
> enough, but it seems unlikely.

        I suspect that the use of slug-type inductors facilitates the
mechanical design of the pushbotton preset tuner.  While there are piston-type
capacitors, they are generally used for higher frequencies than AM broadcast
band (since the capacitance range available is typically << 100 uuF); in
addition, I would guess that a piston-type capacitor is more expensive to
manufacture than a comparison inductor.

==>  Larry Lippman @ Recognition Research Corp., Clarence, New York        <==
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