[Elecraft] Considering a KPA-500

[Fred Jensen]

Interesting idea, pretty hard to read.  If it had columns to start with, 
they went away in the email for me -- maybe not for others.  The real 
measure is $US/dB gained at the other end, but see below.

dBm is power in dB referenced to 1 mW.  1mW=0 dBm.  1W=+30 dBm. 
100W=+50dBm.  700W [KPA500 full bars]=+58.45dBm.  1500W=+61.76 dBm

With larger powers measured in watts, it is common to use dBW -- power 
in dB referenced to 1 watt.  1W=0dBW.  100W=+20dBw.  700W=+28.45dBW. 
1500W=+31.76dBW.  dBW=10*log(power), which is a tad simpler.

1 S-unit is [nominally] 6 dB with S9=50uV at receiver input.  If the 
input Z is 50 ohms, that equates to -73 dBm.

$US per S-unit at the other end sort of says it.  Would be interesting 
to see what the $US per S-unit is for various antenna arrangements. 
There is also a "panadapter gain" [similar to "coding gain"] in that 
being able to watch the whole pile-up lets you find the guy he just 
worked and gives you an advantage, in dB.  If you live in the middle of 
the country, there is a "Stepp-ir gain" in that you can reverse that 
antenna almost instantly in a contest.  I don't know how to quantify P3 
gain or Stepp-ir gain however. :-)

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015
- www.cqp.org


On 4/24/2015 11:48 PM, Nick - VE3EY wrote:

> In addition to conventional "$ per watt" breakdown,  I have also included
> "$ per dBm".   It basically tells you how much each additional decibel of
> gain over 100 watt output power will cost you based on the estimated power
> output , purchase price and gain as compared to your typical barefoot rig.
>
> For power output I have made some rough estimates as to how much power a
> given amplifier can produce.   The prices I have collected today from
> various vendor or dealer web sites.   May not be entirely accurate but you
> get an idea.