K3 - small power supply 110-240VAC

[Phil LaMarche-2]

That's interesting.  I have a RM 70 that has been turned on for over 15
years with no problems and a RS-35 for 10 years w/o a problem.  Rock Solid.

Phil


Philip LaMarche
 
LaMarche Enterprises, Inc
[hidden email]
www.LaMarcheEnterprises.com
 
727-944-3226
727-937-8834 Fax
727-510-5038 Cell
 
www.w9dvm.com
 
K3 #1605
 
CCA 98-00827
CRA 1701
W9DVM
 

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of george fritkin
Sent: Wednesday, August 18, 2010 12:45 PM
To: [hidden email]
Subject: Re: [Elecraft] K3 - small power supply 110-240VAC

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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[Don Cunningham]

Same here, Phil.  RS and RM50's, but same results.  Only lightning has
gotten one in a LOT of years, hi.  My fault then, as I was powering some of
my wireless internet setup with it, hi.  I wonder if the Astrons referenced
might have been switchers??
73,
Don, WB5HAK

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[Craig Smith]

I don't feel that you are being quite fair (or accurate) in regard to the
Gamma power supply.  It is indeed a unique design that trades off continuous
power rating vs. size and weight.  I have one, and think it is an excellent
tradeoff for its intended applications.

You definitely cannot run a 100 W transceiver in AM, FM or RTTY modes with
it - nor was that the intent.  

But for lower duty cycle modes, such as most of us use - CW and SSB - it is
excellent.  I'm not a SSB guy, but I can run my K3 with it on CW at 75W out
without the DC going below 13 V.  That makes it excellent for portable use.
I expect that it would deliver at least that much power on SSB.

<> *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!
 
Not exactly.  Most transceivers are less than 50% efficient at these power
levels.  With 30 W output during tune, the input current can be up to 5A,
which is the continuous duty rating of the Gamma supply.

By the way, besides being small, the supply is quite reliable and
acoustically quiet.


          73   Craig  AC0DS


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[Joe Subich, W4TV-4]

 > That's interesting.  I have a RM 70 that has been turned on for
 > over 15 years with no problems and a RS-35 for 10 years w/o a
 > problem.  Rock Solid.

The RM-35 (linear) supply is my absolute favorite for powering
a 100 W 13.8V transceiver.  If it is an older unit with the captive
cord, I would recommend removing the MOV that is connected from
line to Neutral and the bypass capacitor connected from neutral to
ground.  The capacitor does not appear to be rated for line voltage
and the MOV is in circuit even when the supply is turned off.  Both
of those concern me as matters of safety.

73,

    ... Joe, W4TV


On 8/18/2010 12:55 PM, Phil LaMarche wrote:

>
> That's interesting.  I have a RM 70 that has been turned on for over 15
> years with no problems and a RS-35 for 10 years w/o a problem.  Rock Solid.
>
> Phil
>
>
> Philip LaMarche
>
> LaMarche Enterprises, Inc
> [hidden email]
> www.LaMarcheEnterprises.com
>
> 727-944-3226
> 727-937-8834 Fax
> 727-510-5038 Cell
>
> www.w9dvm.com
>
> K3 #1605
>
> CCA 98-00827
> CRA 1701
> W9DVM
>
>
> -----Original Message-----
> From: [hidden email]
> [mailto:[hidden email]] On Behalf Of george fritkin
> Sent: Wednesday, August 18, 2010 12:45 PM
> To: [hidden email]
> Subject: Re: [Elecraft] K3 - small power supply 110-240VAC
>
> 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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>
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>
>
>
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