I just received my 150' of RG213u to replace the 100' of the same coax. The problem was that I needed a few more feet in the shack, but mostly I needed to get my antenna up about 10' higher.
Am running a fan dipole covering 80, 40, 20, & 15m. I plan to set up 80m in an NVIS configuration for local traffic, while running the 40m-15m in an inverted V configuration to get further than a few hundred miles (near/far news and communication capability).
Currently my antenna is not high enough and it is contributing to some cancelation issues on 80m that I was thinking would be corrected by getting it a bit higher...but have I compromised by also adding more "loss" with the additional 50' of coax?
Quote from: White Tiger on February 10, 2013, 02:50:49 AM
...150' of RG213u to replace the 100' of the same coax.
...but have I compromised by also adding more "loss" with the additional 50' of coax?
No. At HF frequencies it's nearly insignificant.
For future projects here's quick calculator link; select your cable type from the drop-down, plug in your frequency & length & do the what-if's.
http://www.timesmicrowave.com/cgi-bin/calculate.pl
Quote from: KC9TNH on February 10, 2013, 07:24:33 AM
Quote from: White Tiger on February 10, 2013, 02:50:49 AM
...150' of RG213u to replace the 100' of the same coax.
...but have I compromised by also adding more "loss" with the additional 50' of coax?
No. At HF frequencies it's nearly insignificant.
For future projects here's quick calculator link; select your cable type from the drop-down, plug in your frequency & length & do the what-if's.
http://www.timesmicrowave.com/cgi-bin/calculate.pl
Thanks Wes!
Quote from: KC9TNH on February 10, 2013, 07:24:33 AM
Quote from: White Tiger on February 10, 2013, 02:50:49 AM
...150' of RG213u to replace the 100' of the same coax.
...but have I compromised by also adding more "loss" with the additional 50' of coax?
No. At HF frequencies it's nearly insignificant.
For future projects here's quick calculator link; select your cable type from the drop-down, plug in your frequency & length & do the what-if's.
http://www.timesmicrowave.com/cgi-bin/calculate.pl
Wes, I used the information as if I were setting up my 2m Icom IC-271, using 100' of RG213 and I get a loss of 2.4db per 100' and an efficiency rating if 57.6...but I don't have any reference for whether that's good or bad?
...and when it calculates power...is that (.085 kW) the power needed to reach that efficiency?
What about adding a jumper or an added length of something not as robust?
Example, for 2m/440 i have a Diamond stick on the side of the house w/o my electrical feed on it. My shack is opposite of that so i ran 50' of LMR-400 to my shack. I sometimes will add a UHF to SMA jumper for my HT or add 20' of RG-58 to get it across the room to my FT-857.
Will loss only occur on the smaller lengths of coax?
The losses from each section of cable will add. The main thing to remember is the higher the frequency the higher the loss. Also, in general, the thinner the cable the higher the loss.
Using the timesmicrowave.com calculator at 2M frequencies:
50' of LMR-400 = 0.8dB (84% efficiency)
20' of RG-58 = 1.1dB (78%)
So your total loss is 1.9dB (66% efficiency)
Considering 1 "S" unit is 4:1 change in power (400%), your losses even at 146MHz are negligable.
Loss increases with the square root of frequency, so losses at 440MHz will be sqrt(3)=1.73 times higher.