[Elecraft] [KPA500]KPA500 power cord question

[Fred Townsend]

I will add a few comments to Cookie's good advice. If you are wondering if
your ham shack is wired with 15 or 20 amp service here is an easy way to
tell. There are two common types of grounded duplex receptacles available in
the USA. The NEMA 5-15R type has two parallel blades with the U ground pin
on top and the right hand neutral blade is somewhat larger. This receptacle
is rated for 15 amps and is normally wired with 14 gage wire. The NEMA 5-20R
receptacle looks much the same except the right hand blade is T shaped (the
T is laying down) and should be wired with 12 gage wire. NEMA 5-20R plugs
are usually listed as 'Industrial' and therefore not necessarily found in
the same electrical section of Home Depot. 

If you are installing a new circuit 240 VAC is preferable. The current is
less and therefore the copper losses lower and everything, including your
power supply, runs cooler. 
de Fred, AE6QL

-----Original Message-----
From: elecraft-bounces at mailman.qth.net
[mailto:elecraft-bounces at mailman.qth.net] On Behalf Of WILLIS COOKE
Sent: Wednesday, May 04, 2011 5:29 AM
To: Monty Shultes; Ron D'Eau Claire
Cc: elecraft at mailman.qth.net
Subject: Re: [Elecraft] [KPA500]KPA500 power cord question

If you have a dedicated 120V circuit for your ham shack and only run one
transceiver and one medium power amp you will probably be OK.  The trouble
comes from using a house circuit that already has other users and was
designed for those users.  Many house circuits use #14 wire and are good for
15 amps max. You may already have the lights in the room and a few clocks
and other things. Add on a TV set and your wife's hair dryer and you are in
trouble, so you need to do a load analysis.  If you are going to run another
circuit, it might as well be 220, or run two more circuits, a 110 and a
220.  But, you are never safe to just plug in several medium to high current
loads without doing at least an informal load analysis.  If you have too
many loads on a circuit you will soon lose your claim to "Never popping a
breaker".
 Willis 'Cookie' Cooke
K5EWJ 




________________________________
From: Monty Shultes <montys at mindspring.com>
To: Ron D'Eau Claire <ron at cobi.biz>
Cc: "elecraft at mailman.qth.net" <Elecraft at mailman.qth.net>
Sent: Wed, May 4, 2011 5:49:25 AM
Subject: Re: [Elecraft] [KPA500]KPA500 power cord question

I have been using an ALS-600, the 600-watt Ameritron solid state amp, for
two years.  My shack is wired for 120 volts, 20 amps, 2 circuits.

The voltage from the power supply drops only slightly when transmitting,
almost surely from internal factors, not house wiring.  The AC mains voltage
does not drop.

I have never tripped a breaker.

The Elecraft Amp is probably more power efficient than the ALS-600 with its
sophisticated power supply.  I'd worry about something else.

FWIW.

Monty K2DLJ




> The important point is whether the voltage to the finals at full 
> output is as different when the KPA500 is supplied by 240 or 120V 
> mains. I believe the answer is "no". AFAIK, the KPA500, and it's power 
> supply, was designed and tested to meet all of its performance 
> specifications with either a 120V or 240V mains supply. - Ron D'Eau 
> Claire
> 
> 
> 
>> 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.  - Joe Subich

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