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Do I Need a 1:1 SWR?
No—this is a common misconception. For example, if the SWR is 2:1, the loss in transmitted signal
strength will be only about 0.5 dB. Of course the KAT1 always tries to hit 1:1, and with most antennas it will find an SWR below 1.5:1 on most bands. If the SWR is higher than 3:1, try using a balun (see below).
Using Baluns and RF Isolation Chokes
A balun converts a balanced antenna or feedline to unbalanced (one side grounded) to work with your tuner. A balun can also perform an impedance transformation and/or help isolate the antenna from the rig to reduce RF pickup. You may need a balun if: (1) you're using balanced feedline; (2) you're having trouble matching an antenna on one or more bands; (3) you notice RF feedback or get an RF burn. A low-loss, broad-band, 4:1 balun is a good choice, and may solve all three problems. A 9:1 or 4:1 balun is often used with open-wire line. A 1:1 balun or coaxial isolate choke (current balun) will also work in many cases. Balun design is covered in many publications, including the ARRL Handbook. Also check the Elecraft web site (
www.elecraft.com) for antenna-related application notes.