[Elecraft] KPA500 Power Supply Environmental/Ergonomic Issue

[John Marvin]

Dave,

Perhaps you want to turn on your amp manually each time. But what you 
may have missed is that 7 watts is doing more than just detecting 
whether the power switch on the front is used or not. When the KPA500 is 
"off" the RS-232 connection on the back is still live, and there is a 
processor in the KPA500 that is monitoring that connection. You can 
remotely turn on the KPA500 using the KPA utility.  For those whose 
KPA500's are in a remote location, or just in an inconvenient location 
(i.e. not adjacent or within easy reach of your operating position), 
this is a very nice feature. It would be more than just the "power 
supply system" that would need to be redesigned.

73,

John
AC0ZG

On 1/31/2017 8:45 PM, Dave AD6A wrote:
> I recently added a KPA500 kit for my home station. It went together just
> fine, and overall I love it.
>
> There is one thing about the way it works that bugs the engineer and
> environmentalist in me.
>
>   
>
> Before I bought the PA, I thought I'd be able to turn it on/off entirely
> using the ON button on the front panel.
>
> I thought that maybe there was a supercap or backup battery that kept the
> button's electronics alive to perform the ON button function (like TV's have
> in them).
>
> However, it doesn't work like this. In order to turn the PA off completely,
> you have to turn off the main power switch on the rear panel.
>
>   
>
> The front panel ON button powers up the PA from what looks like a cold
> state, however, my measurements are as follows:
>
>   
>
> 1.	With the main power switch on the back panel turned OFF, the PA
> takes no power at all (0.0W)
> 2.	When you turn the main power switch on the back panel to ON, the PA
> draws 6.9W continuously from the 120V AC power supply
> 3.	When you press the front panel ON button, the PA turns "ON" and
> takes around 13W (measured) in STBY mode
>
>   
>
> My home station line up (K3s, P3, 2x SP3, KPA500, KAT500) sits on a large
> operating desk with a shelf unit that I build above the station. My computer
> monitors sit on the shelf above the radios.
>
> There is only just enough height clearance (about 2.5") between the top of
> the KPA500 and the underside of the shelf to allow me to put my hand over
> the top of the PA to reach the main power switch.
>
> It's fiddly but I can do it, it's just that it's a major inconvenience not
> being able to turn the KPA500 truly off from the front panel.
>
>   
>
> Why is the KPA500 designed this way?
>
> In all good conscience, I can't live with the PA consuming 7W all day, every
> day - that's incredibly wasteful.
>
> I suppose I could put a more-easily-reachable external AC power switch on
> the side of my shelf unit to cut power to the whole desk, but that'd be
> ugly.
>
> I'd prefer that either a) the KPA500's main power switch was on the front
> panel, or b) the power supply system was redesigned so it only takes a few
> microwatts when power is applied but the ON button is OFF (not pressed, or
> pressed an even number of times).
>
>   
>
> Comments? Ideas?
>
>   
>
> Cheers,
> Dave AD6A
>
>