Re: [Elecraft] Coax Switches / dBm & W in python
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 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 >> __ Elecraft >> mailing list Home: >> http://mailman.qth.net/mailman/listinfo/elecraft Help: >> http://mailman.qth.net/mmfaq.htm Post: >> mailto:Elecraft@mailman.qth.net >> This list hosted by: http://www.qsl.net Please help support this >> email list: http://www.qsl.net/donate.html Message delivered to >> mike.ab...@gmail.com > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to w...@w2xj.net > __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Coax Switches / dBm & W in python
On 2/17/19 4:32 PM, Andy Durbin wrote: " 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." Does dividing 1,500 by 10 to the power of 6 really need a computer and a Python script? Why not just move the decimal point 6 times? 73, Andy, k3wyc Bad example. :-) Use messier numbers. General shack use for quick conversions is the point. 73, Mike ab3ap __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Coax Switches / dBm & W in python
Thanks for the math stuff! 'Specially that last line. Good to know. Also, some emails asked where I get/what is a slip on PL259. Go here: https://www.rfparts.com/rfp530.html May be others, but that is where I got my newest ones. Bill W2BLC K-Line __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
[Elecraft] Coax Switches / dBm & W in python
" 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." Does dividing 1,500 by 10 to the power of 6 really need a computer and a Python script? Why not just move the decimal point 6 times? 73, Andy, k3wyc __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Coax Switches / dBm & W in python
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 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to mike.ab...@gmail.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
