K3 - small power supply 110-240VAC

[Jorge Diez - CX6VM]

Hello,

 

Do you know about a good power supply for the K3, to be used in any country
and lightweight?

 

Thanks,

Jorge

CX6VM/CW5W

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[pbunn]

I have a K3 that I have used for over a year and a half and I love it. About
11months ago , I bought the 100 watt option - but never installed it and now
I have the 2 meter option and plan to do both at once. Is there anything I
need to look out for. Thanks.

Pat
N4LTA


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[Bud Semon N7CW]

Jorge,

I like the Samlex 1223.  It operates on 110 or 220, 50 or 60Hz and is very
quiet.  We used them at 9L5A last year for CQWW CW and I have used one at
home for years.

73, Bud  N7CW

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Jorge Diez - CX6VM
Sent: Tuesday, August 17, 2010 12:37 PM
To: [hidden email]
Subject: [Elecraft] K3 - small power supply 110-240VAC

Hello,

 

Do you know about a good power supply for the K3, to be used in any country
and lightweight?

 

Thanks,

Jorge

CX6VM/CW5W

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[Sverre Holm (LA3ZA)]

Nothing beats the Gamma Research Power supply when it comes to small size: 1.25 lbs - 0.57 kg. I use it with my K2 for travelling. It takes 100-250 VAC, 50-60 Hz

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

[KE4INM]

Check out the new power supply from Powerwerx with power poles and
*Input Range: 100-120 VAC or 200-240 VAC, 50/60Hz (Switchable) New!*
Output Voltage: 13.85 VDC fixed
Output Amperage: 25 continuous, 30 surge
http://www.powerwerx.com/batteries-chargers/powerwerx-30-amp-desktop-switching-power-supply-powerpoles.html#desc



On Tue, Aug 17, 2010 at 5:21 PM, Sverre Holm (LA3ZA) <[hidden email]> wrote:

>
> Nothing beats the Gamma Research Power supply when it comes to small size:
> 1.25 lbs - 0.57 kg. I use it with my K2 for travelling. It takes 100-250
> VAC, 50-60 Hz
>
> http://www.gammaresearch.net/hps-1a.html
>
>
>
> -----
> Sverre, LA3ZA
>
> K2 #2198, K3 #3391
> http://www.qslnet.de/member/la3za/K2/mod.html LA3ZA Unofficial Guide to K2
> modifications
> --
> View this message in context:
> http://elecraft.365791.n2.nabble.com/K3-small-power-supply-110-240VAC-tp5433673p5434089.html
> Sent from the Elecraft mailing list archive at Nabble.com.
> ______________________________________________________________
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[Bud Semon N7CW]

I suggested this PS to the 9L5A gang last year and was informed that it
worked fine for casual operation, but did not keep the voltage up during
sustained contest operation.  I'm only the messenger on this one - I have no
direct experience with it.  And the VooDoo Contest Group operations are a
pretty severe environment, so our experience may not apply...

73, Bud  N7CW

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Sverre Holm (LA3ZA)
Sent: Tuesday, August 17, 2010 2:22 PM
To: [hidden email]
Subject: Re: [Elecraft] K3 - small power supply 110-240VAC


Nothing beats the Gamma Research Power supply when it comes to small size:
1.25 lbs - 0.57 kg. I use it with my K2 for travelling. It takes 100-250
VAC, 50-60 Hz

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



-----
Sverre, LA3ZA

K2 #2198, K3 #3391
http://www.qslnet.de/member/la3za/K2/mod.html LA3ZA Unofficial Guide to K2
modifications
--
View this message in context:
http://elecraft.365791.n2.nabble.com/K3-small-power-supply-110-240VAC-tp5433
673p5434089.html
Sent from the Elecraft mailing list archive at Nabble.com.
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[Phil Salas]

For portable use, I like the MFJ-4125.  For my main station, I like the Samlex 1235.

Phil - AD5X
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[Jorge Diez - CX6VM]

Thanks Bud,

>From the manual:  "Recommended supply: 13.8VDC @ 25A, continuous duty for
K3/100;

Do you use it full 48 hours without problem during contests?  This is a 23A
PS... Anyway they have another model for 30A.

If the brand is good will consider it.

Here I only find China PS´s!..  and I wantot avoid them

73,
Jorge
CX6VM/CW5W

-----Mensaje original-----
De: Bud Semon N7CW [mailto:[hidden email]]
Enviado el: Martes, 17 de Agosto de 2010 05:11 p.m.
Para: 'Jorge Diez - CX6VM'; [hidden email]
Asunto: RE: [Elecraft] K3 - small power supply 110-240VAC

Jorge,

I like the Samlex 1223.  It operates on 110 or 220, 50 or 60Hz and is very
quiet.  We used them at 9L5A last year for CQWW CW and I have used one at
home for years.

73, Bud  N7CW

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Jorge Diez - CX6VM
Sent: Tuesday, August 17, 2010 12:37 PM
To: [hidden email]
Subject: [Elecraft] K3 - small power supply 110-240VAC

Hello,

 

Do you know about a good power supply for the K3, to be used in any country
and lightweight?

 

Thanks,

Jorge

CX6VM/CW5W

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[Joe Subich, W4TV-4]

Unfortunately the fan noise in the current MFJ-4125P is much
worse than the older units.  The sheet metal has been changed
causing significant restriction in the air flow and the fan
is now operated from the full 13+ volt output presumably to
recover efficiency.

The changes make it noisier than any supply I've seen in a
very long time and not even suitable for tucking under the
operating table.

73,

    ... Joe, W4TV


On 8/17/2010 6:31 PM, Phil & Debbie Salas wrote:

> For portable use, I like the MFJ-4125.  For my main station, I like the Samlex 1235.
>
> Phil - AD5X
> ______________________________________________________________
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[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Bud Semon N7CW]

Jorge,

Yes, we use several of the same supplies for the full 48 hours with no
problems and no RFI.  You must remove an internal jumper wire for 220V
operation.  You can see the eham reviews at
http://www.eham.net/reviews/detail/ .  I did look at the PowerWerx supply -
it is smaller and rated at 25A and the USA price is within $10.  It is
apparently brand new - it doesn't have a eham review page and it is not in
stock.  So there won't be any reliability or RFI data for a while.

73, Bud  N7CW

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Jorge Diez - CX6VM
Sent: Tuesday, August 17, 2010 3:40 PM
To: [hidden email]
Subject: Re: [Elecraft] K3 - small power supply 110-240VAC

Thanks Bud,

>From the manual:  "Recommended supply: 13.8VDC @ 25A, continuous duty for
K3/100;

Do you use it full 48 hours without problem during contests?  This is a 23A
PS... Anyway they have another model for 30A.

If the brand is good will consider it.

Here I only find China PS´s!..  and I wantot avoid them

73,
Jorge
CX6VM/CW5W

-----Mensaje original-----
De: Bud Semon N7CW [mailto:[hidden email]]
Enviado el: Martes, 17 de Agosto de 2010 05:11 p.m.
Para: 'Jorge Diez - CX6VM'; [hidden email]
Asunto: RE: [Elecraft] K3 - small power supply 110-240VAC

Jorge,

I like the Samlex 1223.  It operates on 110 or 220, 50 or 60Hz and is very
quiet.  We used them at 9L5A last year for CQWW CW and I have used one at
home for years.

73, Bud  N7CW

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Jorge Diez - CX6VM
Sent: Tuesday, August 17, 2010 12:37 PM
To: [hidden email]
Subject: [Elecraft] K3 - small power supply 110-240VAC

Hello,

 

Do you know about a good power supply for the K3, to be used in any country
and lightweight?

 

Thanks,

Jorge

CX6VM/CW5W

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[Jon Zaimes AA1K]

Jorge,

I bought an MFJ-4125 Mighty Lite for a trip to J79 about 6 years ago,
and used it on several other portable operations to run an IC706 and a
second one for RX only. It puts out 22A continuous, 25 amp peak in a
small size off either 120/240v. And I see the price is now somewhat less
than when I bought it.
http://www.mfjenterprises.com/Product.php?productid=MFJ-4125

I started using this as my main supply for the K3 almost a year ago and
it has worked great.

73/Jon AA1K



On 8/17/2010 15:37 PM, Jorge Diez - CX6VM wrote:

> Hello,
>
>
>
> Do you know about a good power supply for the K3, to be used in any country
> and lightweight?
>
>
>
> Thanks,
>
> Jorge
>
> CX6VM/CW5W
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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>
>    

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[Will - AI4VE]

I picked up one of the PowerWerx supplies at Dayton this spring and used it for Field Day. It powered my K3 for 24 hours of continuous use with no problems. Have not found any spurs yet. It is amazingly small and portable but the fan noise is noticeable. I don't find it objectionably loud, but it's not silent.

Will, AI4VE
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[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Joe Subich, W4TV-4]

 > I run my K3 from an Astron 20A with no problems at all. The 20A
 > is rated at 20A Intermittent Commercial and Amateur Service (ICAS)
 > and 16A continuous commercial service (CCS).

Ah, but there is a significant difference in the rating between
a linear supply (your Astron RS-20) and a switching supply like
the MFJ-4125 or similar.  The Astron is rated for average current
and duty cycle ... it can almost certainly provide more than 20A
on short peaks ... the 20A rating is based on heating of the
transformer and regulator transistors.

A switching supply is generally rated for CCS with peak current
rating based on the energy storage in the capacitors (how much
current can be drawn before the output drops too low) and the
average current based on the capacity of the switching circuit
to keep the capacitor charged (current rating of the inductor,
transformer, and switching devices).

A prime example of the peak/average issue is the Gamma supply.
It does not even tolerate full power CW well at slow speeds and
falls apart completely at 100 W (even 50 W) RTTY because of the
"continuous" current limitations.

The K3 is quite happy with a 25A peak / 20-22A continuous
switching supply.  Since a linear supply generally has sufficient
energy storage in the filter cap because of the need to work with
a much lower ripple voltage than a switcher, a "20A" linear supply
can usually supply the same brief 25A peaks (dynamic load) within
the heating limits of 20A (average) ICAS service depending on the
design of the regulator (current limiting).

73,

    ... Joe, W4TV


On 8/17/2010 11:52 PM, Ron D'Eau Claire wrote:

> It's okay to apply a little reason when evaluating the specifications. That
> 25A rating is VERY conservative, as Elecraft spex always are IMX.
>
> I run my K3 from an Astron 20A with no problems at all. The 20A is rated at
> 20A Intermittent Commercial and Amateur Service (ICAS) and 16A continuous
> commercial service (CCS).
>
> My K3 demands far less than 20A ICAS, even running 100 watts CW/SSB. Of
> course, that's because both CW and SSB are very low duty cycle modes. The
> peak current (just about 20 Amps worst case for my K3 looking into a low
> SWR) only occurs at brief voice peaks or when the key is actually down in
> CW. The average current is far below that, and far below the 16A CCS rating
> of the Astron.
>
> If I was going to run RTTY or FM at a full 100 watts, I'd be running the
> power supply about 25% above its normal ratings only if I kept transmitting
> for more than 5 minutes (ICAS assumes 5 minutes on and five minutes off).
> Even if I wanted to run RTTY or FM constantly for an extended time, dialing
> the K3 output power back 1 or 2 dB would put the load comfortably inside the
> CCS rating of the power supply.
>
> Ron AC7AC
>
> -----Original Message-----
>
>> From the manual:  "Recommended supply: 13.8VDC @ 25A, continuous duty for
> K3/100;
>
>
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[Jorge Diez - CX6VM]

Thanks all for the suggestions!

73,
Jorge
CX6VM/CW5W

-----Mensaje original-----
De: Bud Semon N7CW [mailto:[hidden email]]
Enviado el: Martes, 17 de Agosto de 2010 05:11 p.m.
Para: 'Jorge Diez - CX6VM'; [hidden email]
Asunto: RE: [Elecraft] K3 - small power supply 110-240VAC

Jorge,

I like the Samlex 1223.  It operates on 110 or 220, 50 or 60Hz and is very
quiet.  We used them at 9L5A last year for CQWW CW and I have used one at
home for years.

73, Bud  N7CW

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Jorge Diez - CX6VM
Sent: Tuesday, August 17, 2010 12:37 PM
To: [hidden email]
Subject: [Elecraft] K3 - small power supply 110-240VAC

Hello,

 

Do you know about a good power supply for the K3, to be used in any country
and lightweight?

 

Thanks,

Jorge

CX6VM/CW5W

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[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Joe Subich, W4TV-4]

 > *Gamma Research further hedges their rating by adding a footnote
 > to their spex that "Output power should be limited to 25 or 300
 > watts during tune-up or other prolonged key-down operation." At
 > 13.8 VDC that means the supply should not be expected to provide
 > more than 2A continuous!

With a less than 50% DC to RF efficiency for most solid state rigs
(K3 is 36% based on 20A @13.8V for 100 W output), 25 or 30 Watts
output would be close to 5 Amps @ 13.8V assuming 40% efficiency.

73,

    ... Joe, W4TV


On 8/18/2010 11:39 AM, Ron D'Eau Claire wrote:

> Quite true Joe, and that's why it's important to note how the supply is
> rated.
>
> If you're talking about the Gamma HPS1a, it's rated at only 5 amps
> continuous* and they do not offer an ICAS rating. Instead they say it will
> handle 22 amps peak at 25% duty/sec., which I interpret to mean no more than
> 22 amps for up to 250 milliseconds during any 1 second interval. Clearly
> that's useless for supplying anything but SSB voice modulation, and I'd be
> concerned with using it with any degree of compression at that. I'd never
> expect it to support RTTY or FM with the K3 above 10 watts RF output where
> the current demand exceeds the 5 amp rating of the HPS1a.
>
> By comparison the MFJ-4125 with its 22A continuous, 25 A peak rating should
> allow you to put a brick on the key at 100 watts with *most* K3s feeding a
> low SWR. K3's can be well with in factory spec's and show a variation in
> current demand of a few amps at 100W RF out from rig to rig and band to band
> and, of course, the SWR has a big effect on the current needed.
>
> As I noted, with my K3 if I were to run a 100% duty cycle mode like RTTY or
> FM and planned to transmit more than 5 minutes at a time, I might dial back
> the RF output power 1 or 2 dB to keep the Astron 20A within its CCS rating.
>
> Ron AC7AC
>
> *Gamma Research further hedges their rating by adding a footnote to their
> spex that "Output power should be limited to 25 or 30 watts during tune-up
> or other prolonged key-down operation." At 13.8 VDC that means the supply
> should not be expected to provide more than 2A continuous!
>
> -----Original Message-----
>   >  I run my K3 from an Astron 20A with no problems at all. The 20A
>   >  is rated at 20A Intermittent Commercial and Amateur Service (ICAS)
>   >  and 16A continuous commercial service (CCS).
>
> Ah, but there is a significant difference in the rating between
> a linear supply (your Astron RS-20) and a switching supply like
> the MFJ-4125 or similar.  The Astron is rated for average current
> and duty cycle ... it can almost certainly provide more than 20A
> on short peaks ... the 20A rating is based on heating of the
> transformer and regulator transistors.
>
> A switching supply is generally rated for CCS with peak current
> rating based on the energy storage in the capacitors (how much
> current can be drawn before the output drops too low) and the
> average current based on the capacity of the switching circuit
> to keep the capacitor charged (current rating of the inductor,
> transformer, and switching devices).
>
> A prime example of the peak/average issue is the Gamma supply.
> It does not even tolerate full power CW well at slow speeds and
> falls apart completely at 100 W (even 50 W) RTTY because of the
> "continuous" current limitations.
>
> The K3 is quite happy with a 25A peak / 20-22A continuous
> switching supply.  Since a linear supply generally has sufficient
> energy storage in the filter cap because of the need to work with
> a much lower ripple voltage than a switcher, a "20A" linear supply
> can usually supply the same brief 25A peaks (dynamic load) within
> the heating limits of 20A (average) ICAS service depending on the
> design of the regulator (current limiting).
>
> 73,
>
>      ... Joe, W4TV
>
>
> ______________________________________________________________
> Elecraft mailing list
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[Buck - k4ia]

I've used the Gamma on PSK at 30 watts and CW at  100w and no one
complained (I realize that only means no one complained).   I may have been pushing
the envelope but the Gamma met my needs for a small  lightweight portable
supply.  I wouldn't use it full time in the shack when  there are other more
robust choices.  

Buck
k4ia
K3  #101

In a message dated 8/18/2010 11:57:34 A.M. Eastern Daylight Time,  
[hidden email] writes:

> *Gamma Research further hedges their rating  by adding a footnote
> to their spex that "Output power should be limited  to 25 or 300
> watts during tune-up or other prolonged key-down  operation." At
> 13.8 VDC that means the supply should not be expected to  provide
> more than 2A continuous!

With a less than 50% DC to RF  efficiency for most solid state rigs
(K3 is 36% based on 20A @13.8V for 100 W  output), 25 or 30 Watts
output would be close to 5 Amps @ 13.8V assuming 40%  efficiency.

73,

... Joe, W4TV


On  8/18/2010 11:39 AM, Ron D'Eau Claire wrote:
> Quite true Joe, and that's  why it's important to note how the supply is
> rated.
>
> If  you're talking about the Gamma HPS1a, it's rated at only 5 amps
>  continuous* and they do not offer an ICAS rating. Instead they say it  
will
> handle 22 amps peak at 25% duty/sec., which I interpret to mean no  more
than
> 22 amps for up to 250 milliseconds during any 1 second  interval. Clearly
> that's useless for supplying anything but SSB voice  modulation, and I'd
be
> concerned with using it with any degree of  compression at that. I'd never
> expect it to support RTTY or FM with the  K3 above 10 watts RF output
where
> the current demand exceeds the 5 amp  rating of the HPS1a.
>
> By comparison the MFJ-4125 with its 22A  continuous, 25 A peak rating
should
> allow you to put a brick on the key  at 100 watts with *most* K3s feeding
a
> low SWR. K3's can be well with in  factory spec's and show a variation in
> current demand of a few amps at  100W RF out from rig to rig and band to
band
> and, of course, the SWR has  a big effect on the current needed.
>
> As I noted, with my K3 if I  were to run a 100% duty cycle mode like RTTY
or
> FM and planned to  transmit more than 5 minutes at a time, I might dial
back
> the RF output  power 1 or 2 dB to keep the Astron 20A within its CCS
rating.
>
>  Ron AC7AC
>
> *Gamma Research further hedges their rating by adding  a footnote to their
> spex that "Output power should be limited to 25 or  30 watts during
tune-up

> or other prolonged key-down operation." At 13.8  VDC that means the supply
> should not be expected to provide more than 2A  continuous!
>
> -----Original Message-----
>    >  I run my K3 from an Astron 20A with no problems at all. The  20A
>   >  is rated at 20A Intermittent Commercial and  Amateur Service (ICAS)
>   >  and 16A continuous  commercial service (CCS).
>
> Ah, but there is a significant  difference in the rating between
> a linear supply (your Astron RS-20) and  a switching supply like
> the MFJ-4125 or similar.  The Astron is  rated for average current
> and duty cycle ... it can almost certainly  provide more than 20A
> on short peaks ... the 20A rating is based on  heating of the
> transformer and regulator transistors.
>
> A  switching supply is generally rated for CCS with peak current
> rating  based on the energy storage in the capacitors (how much
> current can be  drawn before the output drops too low) and the
> average current based on  the capacity of the switching circuit
> to keep the capacitor charged  (current rating of the inductor,
> transformer, and switching  devices).
>
> A prime example of the peak/average issue is the Gamma  supply.
> It does not even tolerate full power CW well at slow speeds  and
> falls apart completely at 100 W (even 50 W) RTTY because of  the
> "continuous" current limitations.
>
> The K3 is quite  happy with a 25A peak / 20-22A continuous
> switching supply.  Since  a linear supply generally has sufficient
> energy storage in the filter  cap because of the need to work with
> a much lower ripple voltage than a  switcher, a "20A" linear supply
> can usually supply the same brief 25A  peaks (dynamic load) within
> the heating limits of 20A (average) ICAS  service depending on the
> design of the regulator (current  limiting).
>
> 73,
>
>      ...  Joe, W4TV
>
>
>  ______________________________________________________________
> Elecraft  mailing list
> Home:  http://mailman.qth.net/mailman/listinfo/elecraft
> Help:  http://mailman.qth.net/mmfaq.htm
> Post:  mailto:[hidden email]
>
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> Please help support this email list:  http://www.qsl.net/donate.html
>

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[george fritkin]

I have  several of the MFJ-4125 supplies and several of the ASTRON 20 and 35 amp models.  The only ones I have trouble with have been the ASTRONs.  Random failures even when not under load.  Go figure.  MFJs....rock solid.
George, W6GF




--- On Wed, 8/18/10, [hidden email] <[hidden email]> wrote:

From: [hidden email] <[hidden email]>
Subject: Re: [Elecraft] K3 - small power supply 110-240VAC
To: 
Date: Wednesday, August 18, 2010, 9:37 AM

I've used the Gamma on PSK at 30 watts and CW at  100w and no one
complained (I realize that only means no one complained).   I may have been pushing
the envelope but the Gamma met my needs for a small  lightweight portable
supply.  I wouldn't use it full time in the shack when  there are other more
robust choices. 

Buck
k4ia
K3  #101

In a message dated 8/18/2010 11:57:34 A.M. Eastern Daylight Time, 
[hidden email] writes:

> *Gamma Research further hedges their rating  by adding a footnote
> to their spex that "Output power should be limited  to 25 or 300
> watts during tune-up or other prolonged key-down  operation." At
> 13.8 VDC that means the supply should not be expected to  provide
> more than 2A continuous!

With a less than 50% DC to RF  efficiency for most solid state rigs
(K3 is 36% based on 20A @13.8V for 100 W  output), 25 or 30 Watts
output would be close to 5 Amps @ 13.8V assuming 40%  efficiency.

73,

... Joe, W4TV


On  8/18/2010 11:39 AM, Ron D'Eau Claire wrote:
> Quite true Joe, and that's  why it's important to note how the supply is
> rated.
>
> If  you're talking about the Gamma HPS1a, it's rated at only 5 amps
>  continuous* and they do not offer an ICAS rating. Instead they say it 
will
> handle 22 amps peak at 25% duty/sec., which I interpret to mean no  more
than
> 22 amps for up to 250 milliseconds during any 1 second  interval. Clearly
> that's useless for supplying anything but SSB voice  modulation, and I'd
be
> concerned with using it with any degree of  compression at that. I'd never
> expect it to support RTTY or FM with the  K3 above 10 watts RF output
where
> the current demand exceeds the 5 amp  rating of the HPS1a.
>
> By comparison the MFJ-4125 with its 22A  continuous, 25 A peak rating
should
> allow you to put a brick on the key  at 100 watts with *most* K3s feeding
a
> low SWR. K3's can be well with in  factory spec's and show a variation in
> current demand of a few amps at  100W RF out from rig to rig and band to
band
> and, of course, the SWR has  a big effect on the current needed.
>
> As I noted, with my K3 if I  were to run a 100% duty cycle mode like RTTY
or
> FM and planned to  transmit more than 5 minutes at a time, I might dial
back
> the RF output  power 1 or 2 dB to keep the Astron 20A within its CCS
rating.
>
>  Ron AC7AC
>
> *Gamma Research further hedges their rating by adding  a footnote to their
> spex that "Output power should be limited to 25 or  30 watts during
tune-up

> or other prolonged key-down operation." At 13.8  VDC that means the supply
> should not be expected to provide more than 2A  continuous!
>
> -----Original Message-----
>    >  I run my K3 from an Astron 20A with no problems at all. The  20A
>   >  is rated at 20A Intermittent Commercial and  Amateur Service (ICAS)
>   >  and 16A continuous  commercial service (CCS).
>
> Ah, but there is a significant  difference in the rating between
> a linear supply (your Astron RS-20) and  a switching supply like
> the MFJ-4125 or similar.  The Astron is  rated for average current
> and duty cycle ... it can almost certainly  provide more than 20A
> on short peaks ... the 20A rating is based on  heating of the
> transformer and regulator transistors.
>
> A  switching supply is generally rated for CCS with peak current
> rating  based on the energy storage in the capacitors (how much
> current can be  drawn before the output drops too low) and the
> average current based on  the capacity of the switching circuit
> to keep the capacitor charged  (current rating of the inductor,
> transformer, and switching  devices).
>
> A prime example of the peak/average issue is the Gamma  supply.
> It does not even tolerate full power CW well at slow speeds  and
> falls apart completely at 100 W (even 50 W) RTTY because of  the
> "continuous" current limitations.
>
> The K3 is quite  happy with a 25A peak / 20-22A continuous
> switching supply.  Since  a linear supply generally has sufficient
> energy storage in the filter  cap because of the need to work with
> a much lower ripple voltage than a  switcher, a "20A" linear supply
> can usually supply the same brief 25A  peaks (dynamic load) within
> the heating limits of 20A (average) ICAS  service depending on the
> design of the regulator (current  limiting).
>
> 73,
>
>      ...  Joe, W4TV
>
>
>  ______________________________________________________________
> Elecraft  mailing list
> Home:  http://mailman.qth.net/mailman/listinfo/elecraft
> Help:  http://mailman.qth.net/mmfaq.htm
> Post:  mailto:[hidden email]
>
> This list hosted by:  http://www.qsl.net
> Please help support this email list:  http://www.qsl.net/donate.html
>

______________________________________________________________
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______________________________________________________________
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