. SWR is Standing Wave Ratio - the amount of reflected power at any given frequency compared to the power output of the exciter/transmitter. No antenna is perfect - all reflect some RF(radio frequency) energy back down the RF path. That amount compared to the amount up is the SWR. EG - 100watts up (transmitted)and 50 watts down (reflected)is 2:1 SWR. When you refer to the average of the whole frequency band your radio outputs, thats VSWR (VariableSWR). Generally speaking, any SWR less than 2:1 is acceptable for transmit, and many radios run 5:1 for recv side (mostly ignored measurement). The SWR is important because the reflected xmit power becomes heat when it reenters the radio circuitry, and heat means component death - the final PowerAmplifier (PA) transistors being the most common victim.
2. measure SWR between the radio and the output cable. Since we're talking VHF I presume you do not have an impedance matching network or external amplifier (footwarmer) to worry about.
3. Cheap but adequate SWR meters are about $30-50 at any electronics store or catalogue (
www.mouser.com). Simple to use - key the radio, adjust power out to full scale, flip switch to reverse and read ratio....
4. The RF path is the physical connection from the radio output jack to the antenna - your cable and connectors. Use solder-on PL-259 connectors, stress relief collars, wrap with self vulcanizing rubber tape, and seal with ScothKote (3M) or similar. Unless you have a bad connector or cable, your SWR will be independent of the cable length.
5. Strongly advise you spend some time talking this over with your local electronics store for pertinent guidance, or search the net for RF or CB or HAM radio basics..
Linear Mode
