[Elecraft] KPA500 - linear power supply

[Johnny Siu]

Hello George,
 
From my reading of all the replies both on and off-the-list, the main reasons are:
 
1.  it is cheaper to use linear PSU so that the price of KPA500 should be competitive;
2.  maintenance and repair will be easier for a linear PSU;
3.  RFI is so often found in the switching PSU
 
I put this question up in the reflector because I find ICPW-1, VL1000 and TL933 are all using switching PSU.  I think items 1 & 2 above have explained the reason of using linear PSU in KPA500.
 
Voltage fluctuation in the AC mains will affect the linearity of the PSU in KPA500.  However, this will not border me because the reliability of AC power supply in Hong Kong is over 99.9%.  We have never suffered from any power interruption in the past years.
 
See you all next week in Dayton.  

TNX & 73,


Johnny VR2XMC

從︰ george fritkin <georgefritkin at yahoo.com>
收件人︰ Elecraft Reflector <elecraft at mailman.qth.net>
傳送日期︰ 2011年05月12日 (週四) 12:16 AM
主題︰ Re: [Elecraft] KPA500 - linear power supply

I can not believe hams who do not want switching mode supplies in their shack.  This precludes the use of a computer in the shack.  It also means no TVs, printers, and a host of other products.  There is also a false notion that so called linear supplies do not cause RFI.  Study Dirac's delta function and you will understand why they can.
Love my two K3s
George, W6GF



--- On Wed, 5/11/11, Al Lorona <alorona at sbcglobal.net> wrote:

From: Al Lorona <alorona at sbcglobal.net>
Subject: Re: [Elecraft] KPA500 - linear power supply
To: 
Date: Wednesday, May 11, 2011, 9:04 AM

One of the inviolable rules in the W6LX shack is: NO SWITCHING POWER SUPPLIES.

Not to make an incendiary statement, but *all* of them generate RFI. Many people 
will tell you that they've never heard RFI from their switching power supplies, 
but often it's just because they don't know what it sounds like or they haven't 
tuned across the right frequency. 


Why raise the noise floor by even half a dB if you can help it?

Nothing beats a old-fashioned, big, beefy, and quiet linear power supply.

Al  W6LX