Elecraft

KX2, KX3 supply voltage

Classic

List

Threaded

4 messages Options

Dennis L. Haarsager

KX2, KX3 supply voltage

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
______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Nr4c

Re: KX2, KX3 supply voltage

My club used a $20 buck converter from Amazon for FD. Used two AGC batteries in series and dropped to 14.1V. Unit is 20Amp and handles input voltage up to 40 and output from 5-35Volts.

Sent from my iPhone
...nr4c. bill

> On Jul 18, 2018, at 10:50 PM, Dennis Haarsager <[hidden email]> 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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

______________________________________________________________
Elecraft mailing list
Home: http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:[hidden email]

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to [hidden email]

Bob McGraw - K4TAX

Re: KX2, KX3 supply voltage

In reply to this post by Dennis L. Haarsager

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
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]

Nr4c

Re: KX2, KX3 supply voltage

A 1.5 A regulator isn’t going to handle the 12 to 20 A drain of an HF Radio.

Sent from my iPhone
...nr4c. bill

> On Jul 18, 2018, at 11:22 PM, Bob McGraw K4TAX <[hidden email]> wrote:
>
> 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
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]