[Elecraft] K3 power supply recommendations

[Fred Townsend]

Gary, you may be trying to chop the cabbage a bit finer than necessary. If
you take a close look at the input power circuit for the K3 you will see the
power pole voltage is the voltage seen by the circuit breaker and the 100W
amp. The voltage measured by the K3 is after the polyfuse (12A) which feeds
the receiver, fan, and P3 (via the power socket). The fuse drops a little
voltage which is why there is a slight difference in readings. The higher
voltage does not affect the receiver because there are several series
regulators (9V & 5V) that derive their supply from 12A  (post fuse 12V). In
the end it is not that critical except the 100W amp will run cleaner and
cooler as the voltage goes up. Also your external power supply, if linear,
will also run slightly cooler as the output voltage is adjusted upwards.
There will be negligible temperature drop on switching supplies. Of course
there are limits as to how high you can raise the input voltage. Read your
K3 input power specification for this value.

73
Fred, AE6QL
-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Gary K9GS
Sent: Tuesday, April 16, 2013 8:56 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] K3 power supply recommendations

I have a question on adjusting the voltage a bit higher for use with the K3.
I was thinking of 14.5 V, as others have mentioned, and adjusting voltage on
receive.

I have an accurate voltmeter.

Should I set the voltage with the voltmeter measuring at the DC input to the
K3 (at the power pole into the radio) or should I use the internal voltmeter
in the K3?





On 4/16/2013 9:05 AM, Mike Reublin wrote:
> I've used an Astron RS-35M very happily for years. Had to turn it up a tad
for the K3.
>
> Tip: The voltage adjustment is on the under side of the board......
>
> 73, Mike NF4L
>
> On Apr 16, 2013, at 8:03 AM, Tom Branton <TBranton at alvincollege.edu>
wrote:
>
>> The K3 in question is a K3/100.  Thanks,
>>
>> Tom
>>
>>
>>
>> On Apr 16, 2013, at 6:26 AM, "Tom Branton" <TBranton at alvincollege.edu>
wrote:
>>
>>> Good morning everyone ,
>>>
>>> I think I have found a very nicely maintained and equipped K3 to
purchase. Any purchase recommendations as to a well constructed and trouble
free power supply?
>>>
>>> Thanks
>>>
>>> Tom
>>> WD5DFE
>>>
>>>
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-- 


73,

Gary K9GS

Greater Milwaukee DX Association: http://www.gmdxa.org Society of Midwest
Contesters: http://www.w9smc.com
CW Ops #1032   http://www.cwops.org

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