[Elecraft] Voltage drop in DX Power to K3

[N4ZR]

Thanks, Bob - I had forgotten about being able to measure at the acc 12v 
output.  In any case, though, the front-panel display provides a pretty 
good number.  It says that the RX-only voltage at the K3 is 13.7 volts.  
My worst-case at 100 watts key down is 12.6 - I don't know where the 11 
volts came from.  As someone suggested, it could be as simple as my 
having plugged and unplugged the various powerpoles a few times.

But here's the real bottom line - depending on band, I only need at most 
40 watts to drive my KPA-1500 to full output.  At that level, voltage 
only drops to 13.1, which is plenty good enough.

Thanks everyone for putting up with me - at least, I'm leaving this 
exercise a little smarter than I went in...


73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 4/26/2020 12:32 PM, Bob McGraw K4TAX wrote:
> Oh well, I need another cup of coffee.    I'll try to do better proof 
> reading.  Can't blame that one on auto-correct!
>
> Cutting to the chase........., measure from the power supply POS 
> terminal to the ACC 12V on the K3 radio.    That is the total voltage 
> drop in the POS DC path.  Then do the same for the NEG terminal of the 
> power supply to the ground terminal on the radio. That is the voltage 
> drop on the NEG DC path.  Add those two together and one has the total 
> voltage drop.  Now, step by step, isolate where each amount of voltage 
> drop occurs.
>
> Anytime over 0.5 volts total voltage drop occurs, something needs 
> attention.   Thus DC Pos should be less than 0.25 volt drop and DC Neg 
> should be less than 0.25 volts.  For a total of 0.5 volts drop at the 
> radio.
>
> 73
>
> Bob, K4TAX
>
>
> On 4/26/2020 11:22 AM, Adrian wrote:
>> I got a good chuckle out of that one Bob, happens to me often
>>
>>
>> take 2 >
>> The calculation is simple:    E = I x R      current multiplied by 
>> resistance equals the voltage.
>>
>>
>>>
>>> The calculation is simple:    E = I x R      current multiplied by 
>>> amps equal voltage.
>>>
>>> 73
>>>
>>> Bob, K4TAX
>>>
>>>
>>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to n4zr at comcast.net