[Elecraft] KX2, KX3 supply voltage

[Bob McGraw K4TAX]

Why not use a 7812 three terminal regulator?   It will accept up to 30 V 
on the input, deliver 12 V on the output at 1.5 amps. These cost about 
$1.50 or less.    If one needs more current then add a 2N3055H as a pass 
transistor for up to 5 amps of current.

Another choice is a regular AC 120V power supply, remove the transformer 
and bridge rectifier, feed the 24 volts to the unregulated input, where 
the bridge rectifier was connected and you have 12V DC regulated.   
These should be available for $10 to $20 new.  just don't buy a 
switching supply.

73

Bob, K4TAX


On 7/18/2018 9:50 PM, Dennis Haarsager wrote:
> I just bought a 24V 3.5A battery to power my CPAP machine when AC isn’t available. Would be nice if I could use it to power my KX2 or KX3. 24v-12V down converters are cheap, but the only 24V-13.8V one I’ve found so far is an order of magnitude more. Does anyone think the extra cost is worth it in terms of extra tx performance?
>
> 73,
> Dennis, N7DH/1, MM/N7DH
>
> Sent from my iPhone
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