Re:Gamma Research Very Small Switching Power Supply

[KH7T]

I have had one of these supplies for several months.
It works as advertised and easily supports my rigs on 100W SSB and cw.
The advertising does say no radio noise and I have found none.  It has
modern 25 Farad super capacitors in series for a 5 Farad output
capacitance.

It is a perfect companion for my K2/100 dual box setup.

The fact that it is only 1.25 pounds with cable and so small opens up
lots of portable uses.
The input is 85 to 240 volts AC.

John KH7T

Subject:
[Elecraft] Gamma Research Very Small Switching Power Supply
From:
[hidden email]
Date:
Sat, 30 Sep 2006 19:10:25 EDT

To:
[hidden email]


Just got my October issue of CQ and saw a review of this very small power
supply made by Gamma Research, model HPS-1a.  It is 3.37 X 1.55 X 5.25 inches,
rated at 13.8 VDC, 22 amps at 25% duty cycle and 5 amps continuous, and weighing
only 1.25 lbs.  If you do not get CQ, then the company's web site
(www.gammaresearch.net) provides information.

Has anyone tried this with a K2/100 rig?

73,
Henry - K4TMC



_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[n6wg]

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

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]]On Behalf Of John Buck
Sent: Sunday, October 01, 2006 3:01 PM
To: [hidden email]
Subject: Re:[Elecraft] Gamma Research Very Small Switching Power Supply


I have had one of these supplies for several months.
It works as advertised and easily supports my rigs on 100W SSB and cw.
The advertising does say no radio noise and I have found none.  It has
modern 25 Farad super capacitors in series for a 5 Farad output
capacitance.

It is a perfect companion for my K2/100 dual box setup.

The fact that it is only 1.25 pounds with cable and so small opens up
lots of portable uses.
The input is 85 to 240 volts AC.

John KH7T

Subject:
[Elecraft] Gamma Research Very Small Switching Power Supply
From:
[hidden email]
Date:
Sat, 30 Sep 2006 19:10:25 EDT

To:
[hidden email]


Just got my October issue of CQ and saw a review of this very small power
supply made by Gamma Research, model HPS-1a.  It is 3.37 X 1.55 X 5.25
inches,
rated at 13.8 VDC, 22 amps at 25% duty cycle and 5 amps continuous, and
weighing
only 1.25 lbs.  If you do not get CQ, then the company's web site
(www.gammaresearch.net) provides information.

Has anyone tried this with a K2/100 rig?

73,
Henry - K4TMC



_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[KH7T]

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

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
>
>  

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Karl Larsen]

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
>>
>>  
>
> _______________________________________________
> Elecraft mailing list
> Post to: [hidden email]
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft   
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[KH7T]

My test data indicates that my K2 / 100 is happy with the Gamma power
supply.
The K2/100 is specified to run ok down to 11 volts. The K2 is more
tolerant than many rigs when run at supply voltages down to 12 volts
minus line drop.

As I stated, the Gamma does run 100 watt cw with the K2/100.  The Gamma
specifications will not support long Key Down at 100 watts.  I have not
run sufficient testing to see how conservative the Gamma 5 amp steady
state, or 22 amp 25% duty cycle is.  In my operation, even at 100 watt,
cw my average periods of transmission tend to fit in the specified
limits of this supply.  I believe that about 85 watt CW fits within the
specification of this power supply.

Karl, you bring up the subject of heavy compression.  If your
compression is to effectively limit voice peaks so you can have higher
average speech the average current will increase.  The compression
should be adjusted so that background noise is not driving the
amplifier.  If so adjusted, I suspect that the average power will still
be less than CW.  Since the Supply can handle the peak currents easily,
the main question is the true average power over a longer time.
Uncompressed SSB is about 20% and CW is about 40% per the RF Safety table.
It has been my experience that heavily compressed SSB is much less
intelligible than moderate compression even though the S meter moves
higher.  In all of my experiments with compression I have ended up using
much less than I initially thought would be useful.

Digression aside, I am happy with my Gamma Research power supply for
portable use with my KPA/100.

Aloha,
John KH7T

Karl Larsen wrote:

>
>    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.
>

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com