[Elecraft] Gamma Research Very Small Switching Power Supply
Karl Larsen
k5di at zianet.com
Mon Oct 2 07:52:38 EDT 2006
John Buck wrote:
> The voltage on my meter is 13.65 with no load.
> With K2/100 set for 50 watts out the voltage drops to 13.3 with a
> string of 15 wpm dashes.
> At 75 watts it drops to 12.75 volts.
> At 100 watts it drops to 12.2 volts.
>
> Due to the large capacitance, it takes several seconds to drop to the
> levels measured. The voltage is slightly higher, I do have a fuse in
> series between the measurement point and the PS.
> I do not recommend solid straight Key down for several seconds. I
> have not tested it this way.
> The power supply would probably fold back at some point.
> This small amount of testing did not seem to heat the supply much.
> The fan noise is much quieter than the computer under the desk. I
> could not hear it at first.
>
> The K2 does not seem to mind. I would recommend a different PS if you
> want 100 Watt plus CW for extended periods. If you want to run 100
> watt ssb or 75 watts or so of cw and you want a small, quiet
> alternative to a battery then this seems to be a good choice.
>
> It is basically a 35 watt commercial supply module with the addition
> of the very large output capacitors. It is recommended for a max of
> 35 watts continuous like RTTY, AM, FM modes
>
> It is rated for 5 amps continuous or 22 Amps @ 25% duty cycle from the
> HPS-1a data sheet.
> Perfect for 100 watt SSB and use good judgment for cw.
>
> It is more compatible with my k2/100 than with the Orion. The Orion
> does not like it at 100 watts CW. 50 watts seems ok
>
> These are all the answers I know. If you are interested but still
> have questions, you should contact WWW.Gammaresearch.net
Hi John, I bet the company will not provide the tests you give us
here. I summarize your work as proving this power supply is properly
specified by the maker and when you draw high current at 12 VDC the
voltage goes down.
For the low duty cycle of SSB at 100 Watts it will work fine. For
the higher duty cycle of CW you can't run 100 Watts. I run serious
compression on my 100 Watt rig and the duty cycle on SSB is much higher.
I wonder if that will work with this supply.
The power supply has no RF noise output so that is a sure plus.
>
> John KH7T
> no affiliation, just a happy customer.
>
> Robert Tellefsen wrote:
>> John
>> Can you tell us how well regulated the output voltage
>> seems to be between key up and key down?
>> Thanks and 73
>> Bob N6WG
>>
>>
>
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