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K3: How many amps does it draw?

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DOUGLAS ZWIEBEL

K3: How many amps does it draw?

Hi all:

Wondering if anybody has measured this...

I have the K3 with the KPA3, but I run it almost all the time at 5
watts output (5.0 setting).

What is the max amps that this configuration might draw, assuming a
good SWR and a normal voltage (indoor) supply? I want to see "how
small" (but safe) a power supply I can use.

Thanks,
de Doug KR2Q

PS: I already have a 35 amp supply which I'm currently (no pun)
using, but it overkill when I run qrp.
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Dick Dievendorff

RE: K3: How many amps does it draw?

This isn't a direct answer to your question, Doug, but if you're looking for
a physically small supply, consider the Gamma Research HPS-1a. It has enough
current capability for 100-watt transceivers using intermittent duty cycle
modes (SSB & CW). It is about the size of a thick pocket book and weighs
just over a pound.

http://www.gammaresearch.net/hps-1a.html

73 de Dick, K6KR

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of DOUGLAS ZWIEBEL
Sent: Tuesday, February 19, 2008 7:59 AM
To: [hidden email]
Subject: [Elecraft] K3: How many amps does it draw?

Hi all:

Wondering if anybody has measured this...

I have the K3 with the KPA3, but I run it almost all the time at 5
watts output (5.0 setting).

What is the max amps that this configuration might draw, assuming a
good SWR and a normal voltage (indoor) supply? I want to see "how
small" (but safe) a power supply I can use.

Thanks,
de Doug KR2Q

PS: I already have a 35 amp supply which I'm currently (no pun)
using, but it overkill when I run qrp.
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DOUGLAS ZWIEBEL

Re: K3: How many amps does it draw?

Thanks Dick. My error...poorly worded.

By "small," I mean AMPS, not physical size. Sorry!

de Doug KR2Q

On 2/19/08, Dick Dievendorff <[hidden email]> wrote:

> This isn't a direct answer to your question, Doug, but if you're looking for
> a physically small supply, consider the Gamma Research HPS-1a. It has enough
> current capability for 100-watt transceivers using intermittent duty cycle
> modes (SSB & CW). It is about the size of a thick pocket book and weighs
> just over a pound.
>
> http://www.gammaresearch.net/hps-1a.html
>
> 73 de Dick, K6KR
>
>
>
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of DOUGLAS ZWIEBEL
> Sent: Tuesday, February 19, 2008 7:59 AM
> To: [hidden email]
> Subject: [Elecraft] K3: How many amps does it draw?
>
> Hi all:
>
> Wondering if anybody has measured this...
>
> I have the K3 with the KPA3, but I run it almost all the time at 5
> watts output (5.0 setting).
>
> What is the max amps that this configuration might draw, assuming a
> good SWR and a normal voltage (indoor) supply? I want to see "how
> small" (but safe) a power supply I can use.
>
> Thanks,
> de Doug KR2Q
>
> PS: I already have a 35 amp supply which I'm currently (no pun)
> using, but it overkill when I run qrp.
> _______________________________________________
> Elecraft mailing list
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> You must be a subscriber to post to the list.
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>
>

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Darwin, Keith

RE: K3: How many amps does it draw?

Uh, I give up, how many? I'm guessing 3 amps or less. Does your PS
have an meter on it? Can your DMM measure current?

I'd like to know too, but I don't have any concerns since I'll be
running my K3/10 from my Astron 20 amp supply.

- Keith N1AS -
- K2 5411.ssb.100 -
- K3 Wave 3 -

-----Original Message-----
> On Behalf Of DOUGLAS ZWIEBEL
>
> I have the K3 with the KPA3, but I run it almost all the time at 5
> watts output (5.0 setting).
>
> What is the max amps that this configuration might draw, assuming a
> good SWR and a normal voltage (indoor) supply? I want to see "how
> small" (but safe) a power supply I can use.
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k0wa@swbell.net

Re: K3: How many amps does it draw?

In reply to this post by DOUGLAS ZWIEBEL

Here is what the specs quote:

Supply Voltage/current: 13.8 V nominal (11 V min, 15 V max). 17-22 Amps typical in TX (100W). 0.9A minimum RX.

Now at 5 watts...I dunno. One of the ways you can find out is...of course...put an amp meter in line with the rig. If you don't have one, cobble one together with a known meter movement...and .1 ohm resistor and the appropriate multiplier resistor. That should do the trick of getting the data you want.

Lee - K0WA

In our day and age it seems that Common Sense is in short supply. If you don't have any Common Sense - get some Common Sense and use it. If you can't find any Common Sense, ask for help from somebody who has some Common Sense. Is Common Sense divine?
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Jerry Flanders

Re: K3: How many amps does it draw?

Harbor Freight stores have a good little DMM for $4. On sale they are
$2. Yes, they work.

Jerry W4UK

At 11:41 AM 2/19/2008, Lee Buller wrote:

>Here is what the specs quote:
>
>Supply Voltage/current: 13.8 V nominal (11 V min, 15 V
>max). 17-22 Amps typical in TX (100W). 0.9A minimum RX.
>
>
>Now at 5 watts...I dunno. One of the ways you can find out is...of
>course...put an amp meter in line with the rig. If you don't have
>one, cobble one together with a known meter movement...and .1 ohm
>resistor and the appropriate multiplier resistor. That should do
>the trick of getting the data you want.
>
>
>Lee - K0WA

Tom Hammond-2

Re: K3: How many amps does it draw?

In reply to this post by DOUGLAS ZWIEBEL

Doug Zwiebel, KR2Q, posed the following...

>Wondering if anybody has measured this...
>
>I have the K3 with the KPA3, but I run it almost all the time at 5
>watts output (5.0 setting).
>
>What is the max amps that this configuration might draw, assuming a
>good SWR and a normal voltage (indoor) supply? I want to see "how
>small" (but safe) a power supply I can use.

Obviously, this is NOT the absolute answer to your query, but it's
what I just measured on my (Field Test) K3, on 20M CW, into a known
accurate 50 Ohm load with the ATU in BYPASS mode, using an in-line
Fluke 187 DMM in the 10A position and the shortest 'test' clip-leads
(about 4" each) I had available.

K3 #0008

Mode Current (A)

OFF 0.055 A (55 mA)

RX 0.99 A (990 mA)

1W TX 2.56 A

5W TX 3.37 A

10W TX 3.95 A

12W TX 4.14 A (power setting just BEFORE KPA3 enabled)

13W TX 8.90 A (KPA3 just enabled)

Given a small amount of resistive losses in the (alligator clip)
connections to the DC leads, the DC voltage applied to the K3
(measured BY the K3) varied from 13.9VDC (RX), 13.7 VDC (1W TX),
to 13.3VDC (13W TX).

This may (or may NOT) be representative of all K3s... YMMV..

73,

Tom Hammond N0SS

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n6wg

Re: K3: How many amps does it draw?

Hi Tom
I'm curious about one thing.
In the K2 we can cut back on receive current by
menu selections for things like FD on battery power.
Is there any plan for such a capability in the K3?
73, Bob N6WG

----- Original Message -----
From: "Tom Hammond" <[hidden email]>
To: "DOUGLAS ZWIEBEL" <[hidden email]>; <[hidden email]>
Sent: Tuesday, February 19, 2008 9:25 AM
Subject: Re: [Elecraft] K3: How many amps does it draw?

> Doug Zwiebel, KR2Q, posed the following...
>
> >Wondering if anybody has measured this...
> >
> >I have the K3 with the KPA3, but I run it almost all the time at 5
> >watts output (5.0 setting).
> >
> >What is the max amps that this configuration might draw, assuming a
> >good SWR and a normal voltage (indoor) supply? I want to see "how
> >small" (but safe) a power supply I can use.
>
> Obviously, this is NOT the absolute answer to your query, but it's
> what I just measured on my (Field Test) K3, on 20M CW, into a known
> accurate 50 Ohm load with the ATU in BYPASS mode, using an in-line
> Fluke 187 DMM in the 10A position and the shortest 'test' clip-leads
> (about 4" each) I had available.
>
> K3 #0008
>
> Mode Current (A)
>
> OFF 0.055 A (55 mA)
>
> RX 0.99 A (990 mA)
>
> 1W TX 2.56 A
>
> 5W TX 3.37 A
>
> 10W TX 3.95 A
>
> 12W TX 4.14 A (power setting just BEFORE KPA3 enabled)
>
> 13W TX 8.90 A (KPA3 just enabled)
>
> Given a small amount of resistive losses in the (alligator clip)
> connections to the DC leads, the DC voltage applied to the K3
> (measured BY the K3) varied from 13.9VDC (RX), 13.7 VDC (1W TX),
> to 13.3VDC (13W TX).
>
> This may (or may NOT) be representative of all K3s... YMMV..
>
> 73,
>
> Tom Hammond N0SS
>
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Tom Hammond-2

Re: K3: How many amps does it draw?

Hi Bob:

>I'm curious about one thing.
>In the K2 we can cut back on receive current by
>menu selections for things like FD on battery power.
>Is there any plan for such a capability in the K3?
>73, Bob N6WG

I kinda doubt it.

If I recall, we discussed this (among FTs) early on and it was decided that
since the K3 was designed NOT as a 'portable' rig, and that given it's
circuit architecture, it was not all that feasible to attempt to effect
significant savings with regard to operating current.

Wayne may want to elaborate, but this is how I recall the discussion going.

73,

Tom

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