[Elecraft] [KPA500]KPA500 power cord question

Tue May 3 16:42:37 EDT 2011

Right... Thanks for all the input. I think that the portability of the
KPA-500 makes sticking to 110V potentially (excuse the pun) a good
idea, unless local condx demand otherwise....

73,

    ~iain / N6ML

On Tue, May 3, 2011 at 8:39 PM, Ron D'Eau Claire <ron at cobi.biz> wrote:
> No. The KPA500 peak demand is less from your 120 volt outlet than most
> household vacuum cleaners or window air conditioners. And, unless you are
> running a full-carrier mode, the average demand by your KPA500 is far below
> the peak.
>
> Of course, you want to consider all the various stuff you have plugged into
> the circuit you are using for the KPA500. It is a significant load at full
> peak power. It wouldn't be a good idea to share the same circuit with a
> window air conditioner, for example.
>
> Ron AC7AC
>
> -----Original Message-----
>
> Hi Clyde,
>
> Can we boil this down a bit? Would a 220/240V input get me more power
> out of the KPA-500 (vs. a 20A 110V circuit, say)? A cleaner signal?
> Less input power consumed? Anything discernible?
>
>     ~iain / N6ML
>
>
> On Tue, May 3, 2011 at 7:21 PM, Clyde Washburn <k2ue at rochester.rr.com>
> wrote:
>> Currently the nominal voltages for most US power companies is 240/120V
> single phase, although in some areas 120/208V 3-phase is
>> common, with 120V outlets being served by any one phase, and 208V circuits
> being fed across any 2 phases.  Accordingly, most US
>> appliances either have specific performance ratings that differ slightly
> for 208V vs. 240V (resistive heaters and A/C compressors
>> are a common example), or have power supply taps to accommodate either
> (common in electronic equipment).
>>
>> The major advantage of 240V operation is improved voltage regulation:  the
> same circuit, fed with the same wire (such as a common
>> 20A 12 gauge circuit), will have the same resistance in either case.  But
> since the current is roughly half at 240V, the I*R drop
>> will be half, which will be 1/4 the relative amount compared to the
> doubled voltage.  You can see that unregulated supplies will
>> perform much better, if the current is high enough for line drop to be
> noticeable.
>>
>> US plugs and receptacles are rated for either 125V (max) or 250V (max),
> and are non-mating between voltages, for safety.  However
>> 20A receptacles of ether voltage will accept 15A plugs of the same
> voltage, so the ideal hamshack receptacle for a linear is a
>> 250V/20A receptacle wired to a 240V or 208V 20A circuit, which will also
> accept 15A 250V plugs, the smallest and most common type.
>> Since 20A wiring and circuit breakers cost very little more than 15A,
> there is little point in installing 15A circuits, unless it is
>> advantageous to use existing wiring in an house or building where new wire
> installation is difficult.  Please note that if you
>> convert an existing 120V wire run to 208 or 240V, you are obligated by
> code (and common sense) to remark the white (formerly
>> neutral) wire with red paint or tape at all points of access, to identify
> as a "hot" lead.  And receptacle ratings should never
>> exceed the rating of the circuit they are on:  never use a 20A receptacle
> on a 15A circuit.
>>
>> In the specific case of the KPA500, it requires 1000VA (volt-amperes), so
> that is 8.3A at 120V, 4.8A at 208V, or 4.2A at 240V.  8.3A
>> is not a particularly heavy load for a 20A circuit, but if it is a 15A
> circuit or is also loaded with all the other hamshack gear,
>> then either a separate 120V circuit for the linear, or preferably a 240V
> circuit is a good idea.
>>
>> _____________________
>> Clyde Washburn, K2UE
>> 82 Lasalle Pkwy
>> Victor, NY 14564-9610
>> 585-317-7006
>> k2ue at rochester.rr.com
>>
>> -----Original Message-----
>> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of iain macdonnell -
> N6ML
>> Sent: Tuesday, May 03, 2011 2:21 PM
>> To: K2GN
>> Cc: Elecraft - K3
>> Subject: Re: [Elecraft] [KPA500]KPA500 power cord question
>>
>> On Tue, May 3, 2011 at 5:59 PM, K2GN <k2gn at k2gn.com> wrote:
>>> GA,
>>>
>>> I am in the process of rebuilding my shack and planning for the future.
>>>
>>> I will order a KPA500 and want to be ready for it power wise.
>>>
>>> I want to run it on 220V as it is available in a nearby panel.
>>>
>>> Question is:
>>>
>>> The manual states for 220V operation I would need an adaptor or new
>>> plug on the power cord.
>>>
>>> Is this a choice that I have as far as wall outlet and matching plug?
>>> If so, no problem, my electrician can fix it up.
>>>
>>> If it's some special, I need specs for it.
>>
>> I think that's left as an exercise for you ... find a heavy computer power
> cord, cut the plug off, and install one that matches your
>> outlet .. or install a matching pair that you like.
>>
>> I'd be interested to hear about benefits (if any) of running the
>> KPA-500 on 220V vs 110V (in the US)......
>>
>>    ~iain / N6ML
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