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Re: Voltage required for proper radio operation



At 11:17 AM 12/31/2002 -0600, Estes Wayne-W10191 wrote:
>N4XEO wrote:
>
>Most of the radios are rated for 13.8 volts now a days. With the parts
>getting smaller and smaller they just can't run on less than that.
>
>W9AE replies:
>
>The VCO, LO, and mixer circuits in ham radios are generally powered by a 
>regulated internal voltage.  Usually 9.6 Volts or less.  It's not obvious 
>to me why a late-model ham transceiver shouldn't have stable frequency 
>when operated at 13.0 Volts.  Maybe some of us are using DC power supplies 
>that have poor load regulation?  Or maybe the DC power cable has too much 
>resistance or poor connections?
>
>I have used a lawn tractor battery to power my FT-847 at max UHF CW output 
>power, with no noticeable instability of TX Sat VFO frequency.  The lawn 
>tractor battery voltage was approximately 13.0V.  But my 12-gauge DC power 
>cable is only 4 feet long - less than half the length of the original 
>cable set.  And of course the lawn tractor battery voltage doesn't drop 
>when I draw 12 Amps on transmit because it is designed for high current 
>engine starting.
>
>Wayne Estes W9AE
>Mundelein, IL, USA

I agree Wayne, but the bottom line is that the specs say 13.8 volts. This 
is what they are saying is needed. Maybe the regulators are being pushed to 
the max where they need the higher voltage just to make the 9.6 volts or 
whatever!!!

Bill N4XEO



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