[Elecraft] Coax Switches / dBm & W in python

[W2xj]

I generally do DBs in my head. Just remember with power 3 db=2X,  6db-4X, 7DB=5X and 10 db=10X. It scales from there. Every 10 db is a factor of 10. 60 db is a factor of one million. Just divide 1500 by a million.  

For voltage the scale doubles so 20 db is 10X, 6 db is 2X, etc. 

Sent from my iPad

> On Feb 17, 2019, at 4:22 PM, Mike Markowski <mike.ab3ap at gmail.com> wrote:
> 
> 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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