[Elecraft] KPA500 Noise While Off

[hawley, charles j jr]

I’ve only noticed a thump with a piece of equipment which has a power supply when it turns on at a line voltage peak. On the occasion that it turns on at a line voltage zero crossing, it makes no noise at all.

Chuck 
KE9UW

Sent from my iPhone, cjack 

> On Jun 27, 2018, at 2:10 PM, Bob McGraw K4TAX <rmcgraw at blomand.net> wrote:
> 
> Seems that the AC line supplying the equipment has a rather high impedance thus allowing the voltage to suddenly drop under the dynamic load and then surge to a higher than normal value. 
> 
> A dedicated 120V and/or 240V service should be considered for the station power. 
> 
> Laser printers do draw considerable power when they start. 
> 
> Bob, K4TAX
> 
> 
> Sent from my iPhone
> 
>> On Jun 27, 2018, at 2:00 PM, John Simmons <jasimmons at pinewooddata.com> wrote:
>> 
>> My Astron RS35 does the same thing under the same conditions.
>> 
>> -John NI0K
>> 
>> Matt NQ6N wrote on 6/27/2018 1:20 PM:
>>> My KPA500 makes a noticeable hum/thump when the laser printer that is on
>>> the same circuit draws a lot of current.
>>> 
>>> 73,
>>> Matt NQ6N
>>> 
>>> On Wed, Jun 27, 2018 at 12:58 PM Jim Brown <jim at audiosystemsgroup.com>
>>> wrote:
>>> 
>>>>> On 6/27/2018 10:37 AM, Richard Wade wrote:
>>>>> If I had to venture a guess, I would say that somehow the unpowered
>>>> KPA500
>>>>> was picking up noise on the shack wiring.  Very strange. Is that
>>>> possible??
>>>> 
>>>> It is if equipment in your shack is not properly bonded together, and to
>>>> house grounds that are also properly bonded together. Study N0AX's
>>>> recent ARRL book on the topic, to which I contributed, or the slides for
>>>> a tutorial talk I've done at several hamfests.
>>>> 
>>>> http://k9yc.com/GroundingAndAudio.pdf
>>>> 
>>>> 73, Jim K9YC
>>>> 
>>>> 
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> 
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