[Elecraft] K3 power supply recommendation

[W0MU Mike Fatchett]

For a small compact supply the PowerWerx supplies from West Mountain 
Radio are great.  They have a cooling fan and will work on 220 or 110.

For my shack supplies I have Astron RM35 and I think a RM50.

On 4/17/2013 11:19 AM, Edward R Cole wrote:
> Wes,
>
> As that may be (it depends on ambient air temp), most hams are not 
> transmitting key-down for extended time.  In the communication 
> industry the duty-cycle for Tx to Rx time is assumed to be 10%. Most 
> FM equipment is equipped with time out timers that stop continuous 
> transmission after 3-minutes.  Since I will assume you are not talking 
> about FM or AM or digital modes like WSJT, the class of service is 
> ICAS and not CCS.  The Astron 35 will handle 25amps quite nicely.  25a 
> x 13.8v = 345w.  This is probably way above the typical 100w RF CW/SSB 
> radio dc load.  If the amplifier runs at 60% efficiency it will draw 
> 167w (about 12amps).  Add the load of the radio this probably is not 
> more than 17amps.  You can probably add a VHF radio sitting in Rx and 
> still not exceed 25amps (and that is only drawn in transmit 10% of the 
> time of use).
>
> If you run any of the modes that are CCS then adding some air cooling 
> is not a bad idea.  I have fans on my high power VHF and UHF amps to 
> just have a bit more tolerance to heat.  I do use them for FM 
> somewhat, and also are used as drivers for WSJT-eme for the 8877 
> final.  Duty-cycle of WSJT (JT65) is 50% (one minute cycles of 
> key-down followed by one-minute receive).  This is hard-duty on ham 
> equipment so lower the RF power if you run these.  I run 55-60w on my 
> 150w amp to drive the 8877 to 1300-1400w.
>
> My station Astron 50M is fused at the distribution panel for 30A so 
> never exceeds this in any mode.  I have a lot of equipment running at 
> the same time.
>
> 73, Ed - KL7UW
>
> From: "Eugene Balinski" <eugeneb at nni.com>
> To: Wes Stewart <n7ws at yahoo.com>,elecraft at mailman.qth.net,
>     garyk9gs at wi.rr.com
> Subject: Re: [Elecraft] K3 power supply recommendations
> Message-ID: <web-493727653 at admin.nni.com>
> Content-Type: text/plain; charset="ISO-8859-1"
>
> Another vote for the RM-35. I have had mine for over 30
> years.  Not an issue.
>
> Note however that Astron over specs their power supplies.
>  They claim that the RS-35 will do 25A continuous.  It will
> not.  It gets too darn hot.  Given the heatsink, it should
> do about 20 continuous.   This is with static air cooling,
> no forced air.
>
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