[Elecraft] Astron 25 amp supply

[Ron D'Eau Claire]

Astron is very specific about what ICS (Intermittent Communications Service)
means: 50% duty cycle, 5 min on and 5 min off. The limit is almost all about
keeping the regulators working within their design temperature.

Astron's typical ICS rating is about 25% higher than the continuous duty
rating. For example a 20 amp Astron is rated at 20 amps ICS and 16 amps
continuous. That continuous is really continuous. That is, you can demand 16
amps from it 24/7 for year after year and expect reliable operation. I've
worked with many hundreds of them in commercial service and can count the
number of failures on the fingers of one hand. 

Note that a very large number of Astron supplies are used with equipment,
such as FM communications radios and repeaters, that are keyed for a while
demanding a full 20 A current and then switch to receive mode for a while.
Our HF Ham rigs typically have a much smaller duty cycle than specified by
the ICS rating. While someone might yack on SSB or carry on sending CW for
longer than five minutes, our rigs are not pulling full current except on
the occasional voice peaks or when the CW key is actually closed. The
average current is much, much lower than the peak. 

Although Elecraft recommends a 30 amp supply, I have an Astron 20A (linear)
supply that has run my K3 at full power for over three years now. Under most
conditions the peak current demand is under 20 Amps at 100 watts output "key
down" CW, but even when it peaks at over 20 amps the supply handles it
easily.  

Ron AC7AC