[Elecraft] Coax Switches / dBm & W in python

[Mike Markowski]

At work (RF lab), dBm power units let a feeble-minded engineer :-) use 
plus/minus rather than times/divide with Watts for calculations.

For isolation and other calculations in the ham shack where Watts are 
used, a few python one-liners useful.  (Python is free and runs on 
Windows, Mac, linux.)  When in python, copy the following:

from math import *
w2dbm = lambda x: 10 * log10(x/10) + 30
dbm2w = lambda x: 10 ** ((x-30)/10)
iso = lambda pwr_W, iso_dB: dbm2w(w2dbm(pwr_W) - iso_dB)

and now something like

 >>> iso(1500, 60)
0.001500

tells you that 1500 W with 60 dB isolation leaks 1.5 mW to the other port.

73,
Mike ab3ap

On 2/17/19 10:38 AM, James F. Boehner MD via Elecraft wrote:
> I  use the Alpha Delta Series.  They have SO-239 and "N" connector
> models, two position or four position.  For the price difference, I
> always get four position.
> 
> They are not only well built switches, but they do have surge
> protection (gas) with a replaceable pill.  Their best feature is the
> very high isolation they offer:
> 
> 30 MHz  >60 dB 150 MHz >50 dB 450 MHz 50 dB
> 
> And dB Loss:
> 
> 30 MHz  0.1 dB 150 MHz 0.15 dB 450 MHz 0.5 dB
> 
> So, I wish these could be remotable.  However, they are the best
> switches I've found for a reasonable price, and I have many of them
> in my station.
> 
> Oh yes, on the outside of my house, I have polyphasers.
> 
> '73 de JIM N2ZZ
> 
> 
> 
> I do use a number of Daiwa 2-position coax switches for various 
> purposes. Any comments on coax switches?
> 
> Bill W2BLC K-Line
> 
> 
> 
> 
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