Cable & Losses & SWR'ing

Well 27mhz is an interesting band. It is at the high end of the H.F spectrum, and it's at the low end of the V.H.F spectrum. So many people would assume that basically large cable lengths are not lossy at all, well think again. Typical RG-58 coax cable @ 50 ohms has a loss of about 2.5db @ 100ft (approx 33m). Now when the calculations are made 3db (decibels) is have of your power gone! So if you are power hungy don't go spending on another power amplifier until you have your antenna and cable sorted out, because you can put as much power up the cable as you can but if no power can make it to the antenna so no power is radiated, what good is that. I reccomend a cable run over 15m is worth running RG-213. This is also 50ohm cable, so what are the losses? At 100ft ( approx 33m) the cable will loose approx 1db! Now that is a lot less, but can you justify the extra cable costs??? Another deadly way to mismatch your radio's SWR (Standing Wave Ratio) is if the antenna is not tuned probably. Now a SWR of 2:1 on HF is not disasterous but a 1.4:1 SWR like a beam is much better. See below on how to SWR an antenna. Well i hope that you may have learnt something from this exercise.

SWR'ing an antenna

RADIO -> SWR METER ------------------> ANTENNA (Station master, Beam)

            INSIDE              COAX CABLE              OUTSIDE