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120V vs 240V

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W8JH

120V vs 240V

I will need to add a circuit for a KPA-500. It is less than 25 feet from the panel. Other than the cost of wire for the circuit is there any advantage/disadvantage to feeding this amp 120V or 240V? It would have it's own circuit so the voltage droop on 120V would be minimal I guess.

73,

Joe W8JH

K3 1713

73,

Joe, W8JH

K3s, KPA 500, KAT 500 and KX3 happy user.

Barry

Re: 120V vs 240V

For a 500W amp, probably doesn't matter, however, why not plan for the future? Some day, you may want a bigger amp that will require 240V, so put it in now.
Barry W2UP

K4SC

Re: 120V vs 240V

In reply to this post by W8JH

If I were going to the trouble to pull the wire, I'd run 220V. You give yourself the option of using a heavier amplifier in the future, and less voltage drop (twice as much on 120V). You can always use the neutral and one side for 120V now if you really are stuck on it, and use both side of the line, minus the neutral later if you need it. Remember the amplifier output is 600 Watts, the input is well over 1KW. What do the lights in your bathroom do when you or the xyl turn on a hair dryer? Mine dim. Same thing will happen voltage wise when you key the amp.

Chuck K4SC Crystal River, FL

ab2tc

Re: 120V vs 240V

Hi,

Absolutely agree, if you are putting in a new circuit, make it 240V. It's not much more trouble and gives you the choice of local 240 and 120V outlets.

AB2TC - Knut

PS. S9DX still holding up well here and getting rave reports from points west.

K4SC wrote

If I were going to the trouble to pull the wire, I'd run 220V. You give yourself the option of using a heavier amplifier in the future, and less voltage drop (twice as much on 120V). You can always use the neutral and one side for 120V now if you really are stuck on it, and use both side of the line, minus the neutral later if you need it. Remember the amplifier output is 600 Watts, the input is well over 1KW. What do the lights in your bathroom do when you or the xyl turn on a hair dryer? Mine dim. Same thing will happen voltage wise when you key the amp.

Chuck K4SC Crystal River, FL

Don Wilhelm-4

Re: 120V vs 240V

In reply to this post by K4SC

Chuck,

I would not advocate using one side of the 240 volt feed and neutral for
a 120 volt feed. If the need is to run 240 volts to the shack as well
as 120 volts, pull two lines, and put a breaker on each of them. Yes,
your "solution" will work with a 3 wire with ground wiring run, but if
split out to two 120 volt sources, the current on the neutral may exceed
expectations for the wire size used.

A 240 volt AC run can be made with 2 conductors and safety ground. A
120 volt AC run can be made using 2 conductors and safety ground. If
you want 240 volts, start with a 240 volt run from the service panel, if
you want 120 volt service, start with a 120 volt run from the service
panel. Do not mix the two (even though it "works").

Your safety is at stake - stick to the NEC requirements and guidelines.

73,
Don W3FPR

On 2/15/2011 7:25 PM, K4SC wrote:

> If I were going to the trouble to pull the wire, I'd run 220V. You give
> yourself the option of using a heavier amplifier in the future, and less
> voltage drop (twice as much on 120V). You can always use the neutral and
> one side for 120V now if you really are stuck on it, and use both side of
> the line, minus the neutral later if you need it. Remember the amplifier
> output is 600 Watts, the input is well over 1KW. What do the lights in your
> bathroom do when you or the xyl turn on a hair dryer? Mine dim. Same thing
> will happen voltage wise when you key the amp.
>
> Chuck K4SC Crystal River, FL

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ab2tc

Re: 120V vs 240V

Hi all,

I was not advocating using the safety ground of the 240V cable for a neutral return for a 120V outlet (clearly against code). I have not done a a combined 120/240V run myself but I thought it was possible to get a complete red/black/white/blank cable to do this in a single run. Rummaging around in my supply of electrical wire I found a red/black/white piece of cable but curiously it had no safety ground wire. Anyway, I suppose running two cables from two breakers is still not too much trouble.

AB2TC - Knut

Don Wilhelm-4 wrote

Chuck,

I would not advocate using one side of the 240 volt feed and neutral for
a 120 volt feed. If the need is to run 240 volts to the shack as well
as 120 volts, pull two lines, and put a breaker on each of them. Yes,
your "solution" will work with a 3 wire with ground wiring run, but if
split out to two 120 volt sources, the current on the neutral may exceed
expectations for the wire size used.

A 240 volt AC run can be made with 2 conductors and safety ground. A
120 volt AC run can be made using 2 conductors and safety ground. If
you want 240 volts, start with a 240 volt run from the service panel, if
you want 120 volt service, start with a 120 volt run from the service
panel. Do not mix the two (even though it "works").

Your safety is at stake - stick to the NEC requirements and guidelines.

73,
Don W3FPR
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Alan Bloom

Re: 120V vs 240V

In reply to this post by ab2tc

And while you're at it, use the three-wires-plus-ground type Romex. You
need a separate safety ground if you want to have any 110V outlets on
the same circuit.

Al N1AL

On Tue, 2011-02-15 at 16:35 -0800, ab2tc wrote:

> Hi,
>
> Absolutely agree, if you are putting in a new circuit, make it 240V. It's
> not much more trouble and gives you the choice of local 240 and 120V
> outlets.
>
> AB2TC - Knut
>
> PS. S9DX still holding up well here and getting rave reports from points
> west.
>
>
> K4SC wrote:
> >
> > If I were going to the trouble to pull the wire, I'd run 220V. You give
> > yourself the option of using a heavier amplifier in the future, and less
> > voltage drop (twice as much on 120V). You can always use the neutral and
> > one side for 120V now if you really are stuck on it, and use both side of
> > the line, minus the neutral later if you need it. Remember the amplifier
> > output is 600 Watts, the input is well over 1KW. What do the lights in
> > your bathroom do when you or the xyl turn on a hair dryer? Mine dim.
> > Same thing will happen voltage wise when you key the amp.
> >
> > Chuck K4SC Crystal River, FL
> >
>

Scott Ellington

Re: 120V vs 240V

In reply to this post by K4SC

Actually, the percentage voltage drop at 120 V is FOUR times that at 240 V. (For the same power, wire gauge and length.) Since the KPA500, like most tube-type amplifiers, uses an unregulated power supply, the extra drop can significantly reduce output. For example, suppose the amplifier can put out 500 W with a perfectly regulated input of 120 or 240 V. Say the line voltage, at 240 V, drops 6 volts at full output. That's a 2.5 percent drop, which reduces RF output by about 5 percent, to about 475 W. At 120 V, the drop is 12 volts, 10 percent, which reduces the output by about 20 percent, to about 400 W. You just lost 75 more Watts, each of which cost you $4.

Keep in mind that 500 W output requires about 1 kW input, that the power factor of the power supply is considerably less than 1, and that the high peak currents make the effects of line voltage drop even worse. When calculating effective line drop for the KPA500, I would use something like 2 kVA, about 17 A at 120 V. The above example corresponds to a run of 220 feet of AWG 12 (440 feet total), admittedly a very long run.

Bottom line: If you are adding wiring, use 240 V. Run the amplifier on 120 V only if you have no choice, or if the run from the distribution panel is under about 50 feet.

Scott K9MA

On Feb 15, 2011, at 6:25 PM, K4SC wrote:

> If I were going to the trouble to pull the wire, I'd run 220V. You give
> yourself the option of using a heavier amplifier in the future, and less
> voltage drop (twice as much on 120V).

Scott Ellington
Madison, Wisconsin
USA

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Bob K6UJ

Re: 120V vs 240V

I also recommend running a dedicated 220V circuit to the shack for your amp(s) I was plagued with the lights dimming, etc and after
having to reset circuit breakers a few times decided I had to do something ! Yes, some work involved running the romex
cable thru the attic, etc but well worth it.

Bob
K6UJ

Bob
K6UJ
On Feb 16, 2011, at 8:35 AM, Scott Ellington wrote:

> Actually, the percentage voltage drop at 120 V is FOUR times that at 240 V. (For the same power, wire gauge and length.) Since the KPA500, like most tube-type amplifiers, uses an unregulated power supply, the extra drop can significantly reduce output. For example, suppose the amplifier can put out 500 W with a perfectly regulated input of 120 or 240 V. Say the line voltage, at 240 V, drops 6 volts at full output. That's a 2.5 percent drop, which reduces RF output by about 5 percent, to about 475 W. At 120 V, the drop is 12 volts, 10 percent, which reduces the output by about 20 percent, to about 400 W. You just lost 75 more Watts, each of which cost you $4.
>
> Keep in mind that 500 W output requires about 1 kW input, that the power factor of the power supply is considerably less than 1, and that the high peak currents make the effects of line voltage drop even worse. When calculating effective line drop for the KPA500, I would use something like 2 kVA, about 17 A at 120 V. The above example corresponds to a run of 220 feet of AWG 12 (440 feet total), admittedly a very long run.
>
> Bottom line: If you are adding wiring, use 240 V. Run the amplifier on 120 V only if you have no choice, or if the run from the distribution panel is under about 50 feet.
>
>
> Scott K9MA
>
>
> On Feb 15, 2011, at 6:25 PM, K4SC wrote:
>
>> If I were going to the trouble to pull the wire, I'd run 220V. You give
>> yourself the option of using a heavier amplifier in the future, and less
>> voltage drop (twice as much on 120V).
>
> Scott Ellington
> Madison, Wisconsin
> USA
>
>
>
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Phil Salas

Re: 120V vs 240V

In reply to this post by Scott Ellington

I ran 240VAC to my shack for my ALS-600. I have the switching power supply, and the ALS-600 draws very close to 15 amps with the switcher. As my shack is diagonally across the house from the breaker panel, I was actually seeing 20VAC drop in the wiring. This caused two problems: Lots of light flickering in the shack, and sometimes the power supply would trip out because as the input AC dropped, the input AC current would increase and trip the ALS-600 switching supply input current sensor.

However, the KPA500 only draws about 9-amps at 120VAC. While I could set it up for 240VAC (and I probably will one of these days), at 9-amps there is no lamp flickering in my shack, no noticable AC voltage drop, and I can put out the full 500 watts with no problem.

Phil - AD5X
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P.B. Christensen

Re: 120V vs 240V

>I ran 240VAC to my shack for my ALS-600. I have the switching power
>supply, and the ALS-600 draws very close to 15 amps with the switcher. As
>my shack is diagonally across the house from the breaker panel, I was
>actually seeing 20VAC drop in the wiring. This caused two problems: Lots
>of light flickering in the shack...

Phil, was the light dimming occurring before or after your pulled the 240V
branch into the shack? If it was after, I'm curious why the lights would
dim if they're on a 120V branch while the amp is on its own 240V branch.
Seems if they're dimming after pulling the new 240V circuit, then the
dimming is the result of the TRX current and not the amp? Tnx!

Paul, W9AC

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Phil Salas

Re: 120V vs 240V

Sorry - Wasn't clear. The light flickering only occurred when trying to run
the ALS-600 on 120VAC. No problem on 240VAC. However, no problem at all
when running the KPA500 on 120VAC.

Phil - AD5X

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K6LMP

Re: 120V vs 240V

In reply to this post by Phil Salas

Phil, the 20 VAC drop that you describe for a 15 amp draw on a 120 VAC circuit strongly suggests that something is wrong with the wiring.

I am assuming that with a 15 amp breaker the circuit is wired (per the National Electrical Code requirements) with 14 gauge copper wire. A voltage drop of 20 VAC, or 16.3%, would be consistent with a wire run of 250 feet. Even running along the two legs of a triangle (not the more direct hypotenuse), your wire run is probably no more than 60 or so feet, unless you own a very large house. The voltage drop should be 3 or 4 volts at 15 amps, not 20 volts. Either there's a connection in the circuit that is creating some resistance, or the wiring is undersized (unlikely).

If you have an oxidized or otherwise "non-clean" connection (such as a wire that has been arcing under the connecting screw or a loose connection inside a wire nut) you have a real fire hazard. I suggest a careful inspection of every joint in the wire run from the breaker to the outlet. If you don't see anything obvious that you can correct, call an electrician. House wiring is quite different (mechanically, not electrically) from the sort of wiring we're accustomed to dealing with inside a radio chassis. Unless you know for sure what you're doing, and know the NEC requirements, this is a job best left to professionals.

Lew K6LMP

On Feb 16, 2011, at 9:36 AM, Phil & Debbie Salas wrote:

> I ran 240VAC to my shack for my ALS-600. I have the switching power supply, and the ALS-600 draws very close to 15 amps with the switcher. As my shack is diagonally across the house from the breaker panel, I was actually seeing 20VAC drop in the wiring. This caused two problems: Lots of light flickering in the shack, and sometimes the power supply would trip out because as the input AC dropped, the input AC current would increase and trip the ALS-600 switching supply input current sensor.
>
> However, the KPA500 only draws about 9-amps at 120VAC. While I could set it up for 240VAC (and I probably will one of these days), at 9-amps there is no lamp flickering in my shack, no noticable AC voltage drop, and I can put out the full 500 watts with no problem.
>
> Phil - AD5X
> ______________________________________________________________
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VTuff59795

Re: 120V vs 240V

In reply to this post by W8JH

Guys,
you should all emigrate to the UK!

We have 240V AC as standard ;-)

73's

Vic
G7PYR
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Don Wilhelm-4

Re: 120V vs 240V

In reply to this post by K6LMP

Yes, a 20 VAC drop is something that would cause me to look at the
wiring carefully.
If the receptacles are wired using the "backstab" holes rather then
having the wires secured under the screws, that is a possible cause, as
are loose screws in the receptacles.

73,
Don W3FPR

On 2/16/2011 1:04 PM, Lew Phelps K6LMP wrote:
> Phil, the 20 VAC drop that you describe for a 15 amp draw on a 120 VAC circuit strongly suggests that something is wrong with the wiring.
>
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Scott Ellington

Re: 120V vs 240V

In reply to this post by Phil Salas

That's interesting. Does the KPA500 use a choke input supply? (That would considerably reduce the input current.)

Scott K9MA

On Feb 16, 2011, at 11:36 AM, Phil & Debbie Salas wrote:

Scott Ellington
Madison, Wisconsin
USA

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AC7AC

Re: 120V vs 240V

In reply to this post by VTuff59795

CONTENTS DELETED

The author has deleted this message.

Don Cunningham-2

Re: 120V vs 240V

In reply to this post by Don Wilhelm-4

Don Cunningham-2

Re: 120V vs 240V

In reply to this post by Don Wilhelm-4

I guess I'm getting old. Sorry about the blank message!! Don, I found
something interesting in doing some "remodeling" and replacing receptacles.
The old ones were ivory, and with the new white trim, I had to please the
XYL, hi. Anyway, since my wiring days in the sixties, I have avoided the
"backstab" type receptacle myself, knowing that spring HAD to wear out over
the years. I found some receptacles at Lowe's, made by Cooper Industries
that had the "backstab" feature. I was going to wrap the wire under the
screws as I always have BUT these new back entry plugs now use the screw on
the side to run a clamping mechanism against the wire, making a really good
connection!! If one looks at the new plugs, you may be pleasantly surprised
to find this new feature (maybe old by now, but my first experience with
it). I did a "test room" with that method, but will do the rest of the
place the old fashioned way, hi.

By the way, off topic, but I invested in one of the IBM refurbished
computers you recommended and LOVE it!! It looks like a new machine, has a
LOT of memory and a HUGE hard drive, 2 serial ports and a host of USB ones,
3 1/2" floppy dirve, quiet fan and just works well in the shack. Thanks for
making the recommendation. With the "extras" on it, I still didn't spent
$300, which is phenomenal to me.
73,
Don, WB5HAK

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Roger D Johnson

Re: 120V vs 240V

In reply to this post by VTuff59795

[hidden email] wrote:

> Guys,
> you should all emigrate to the UK!
>
> We have 240V AC as standard ;-)
>
> 73's
>
> Vic
> G7PYR
> ______________________________________________________________
>
>

I had 220/380 volt 3 phase at my house in Germany! Unfortunately, they
were 10 Hz short.

73, Roger

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