Basically, this antenna is a 23-foot wire fed through a 4:1 un-un transformer. This antenna can be easily used in portable operation, for operating all bands from 40-10 meters.
A mid-power portable/handheld SSB transceiver for 14MHz
A Rig control CAT interface schematic suitable for both the Yaesu FT-817 and FT-100 transceivers.
This type of antenna is a popular antenna design as the performance is very good across the HF bands and requires little or no tuning. It’s a dipole fed off center with a 4:1 balun at the offset feed point. The antenna shown covers 80, 40, 20 and 10 meters. The formula can also be used to adjust the overall length to cover more or fewer bands and the resulting overall length. 160-10m, 80-10m or 40-10 meters depending on your available space. Other bands will require a tuner.
Inverted L antenna, even if not completely freestanding, it only requires one line to be lauched into a tree to support the end of the horizontal wire. This project is done with a 31-foot Jackite pole for a support and uses six 15-foot radials and one 33-foot radial.
With some fantasy the circuit can be easily assembled on a small scrap of pre-perf board,and then fitted in the DB9 serial connector shell. The interface requires two NPN transistors and few more passive components.
A collection of pictures for a mobile antenna setup for T-hunting.