Power Suppy for K2

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Power Suppy for K2

Samir Popaja
Hello,

Any recomendation for PS for K2?

Which to choose, switching supply or not switching?

Whats the difference between switching supplies and not switching supplies? Pros and cons...

I'm wondering that ELECRAFT hasn't devoloped PS to match design for  K2 or K2/100?

Thanks
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RE: Power Suppy for K2

Darwin, Keith
For my K2, I went with the Astron RS-20M supply.  It is a linear supply,
not a switching supply.  I went that way because I knew it would work,
would generate no noise and would be something I could service down the
road.  I got the 20 amp supply even though my K2 is only 10 watts
output.  Someday, I'll have the 100 watt PA and then my PS will continue
to work my K2.

I believe Elecraft has not developed a PS because it is not cost
effective to do so.  There are people like Astron who specialize in
power supplies.  Elecraft would be hard pressed to come up with a better
supply for the same price or a cheaper supply of equal quality.

TenTec sells power supplies for their radios but as I understand, they
are just Astron supplies with a TenTec logo.  Even TenTec has quit
designing their own supplies.

- Keith KD1E -

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Samir Popaja
Sent: Monday, October 02, 2006 5:15 AM
To: [hidden email]
Subject: [Elecraft] Power Suppy for K2

Hello,

Any recomendation for PS for K2?

Which to choose, switching supply or not switching?

Whats the difference between switching supplies and not switching
supplies? Pros and cons...

I'm wondering that ELECRAFT hasn't devoloped PS to match design for  K2
or K2/100?

Thanks
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Re: Power Suppy for K2

Leigh L. Klotz Jr WA5ZNU
Administrator
In reply to this post by Samir Popaja
For the QRP K2, another good power option is an AGM lead-acid battery in
7 to 40 amp range, a multi-level charger (Battery Tender or Battery
Tender Jr for the smaller batteries, Motorcycle Accesories Warehouse),
and a 5-10W solar panel (EBay, Northern Tool) with Don Brown's
controller for backup, all hooked together with Anderson Power Poles.  
You will be free of RF hash, and as a bonus can operate during power
outages.

73,
Leigh/WA5ZNU
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RE: Power Suppy for K2

Fred (FL)
I purchased a new ASTRON RS-35M, 35 amp 13.8VDC
linear supply - for my ham, and K2 supply needs.
It is more than enough amps, to supply all the
current I may need from several pieces of ham
gear.  Astron supplies are built like tanks,
and they hold their values over many years.
I think the RS-35M was like $130 or $150 total,
from HRO.  Great supply, with amp and voltage
meters too.    IMHO - I'd stay away from any
switcher supplies, no matter how ripple free
they say they are.  Noise is noise .....

Then when Elecraft comes out with their
K3 in 2007 or 08 - I'll be set for that too!

Fred
N3CSY

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Re: Power Suppy for K2

michael taylor-3
In reply to this post by Samir Popaja
On 10/2/06, Samir Popaja <[hidden email]> wrote:
> Which to choose, switching supply or not switching?

I would say choose based on how you plan to use it. In a roomy radio
work area a linear is nice and simple. It can also heat the room which
is nice in Canadian winters. If you have a tiny area or will often
move / carry the power supply you will likely want to choose a
switching power supply.

I personally have a 23A 13.8VDC Samlex model 1223. I've used it on
both 120 and 220VAC with no problems. It requires an easy but many
adjustment to switch input voltage so if you want to use it for
international travel look for a model that works with any input AC
voltage. Just about any will handle both 50 and 60 Hz with no issues.

> Whats the difference between switching supplies and not switching supplies? Pros and cons...

The main factors are size/weight, efficiency, and RF noise.

Switching power supplies are lighter and sizer for equivalent power output.

Switching power supplies are more efficient at converting AC input to
high current regulated DC output 80%-90%+ efficient versus about
30-60% efficiency for linear PS. This causes the amount of heat
generated to vary based on the design type, the heat is a waste
by-product of the inefficiency.

Switching power supplies use a high frequency (20kHz - 2 MHz) in their
conversion process, these can cause harmonic distortion in the RF
frequency range unless properly filtered. I believe switching supplies
will always raise the noise floor due to the nature of how they work,
but I believe they can be filtered and shielded enough to make them
usable in all but the most demanding to weak signal applications.

> I'm wondering that ELECRAFT hasn't devoloped PS to match design for  K2 or K2/100?

Three reasons I can think of are: A linear supply is boring design
wise and very easy to home brew (as hard as a home brew QRP antenna
tuner) and a large transformer needed to power the K2/100 is heavy to
ship, and I suspect the economics were not attractive (Astron have the
majority market share of the US amateur radio market).

-Michael, VE3TIX
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