Dom används för att stämma av antennen då anntennen fungerar utan avstämning (tuner) på 9 band, 80/40/30/20/15/17/12/10/6 Meter
"Theory of Operation The first L/C circuit generates enough reactance to bring the whole HF9V to resonance on 80 meters allowing it to act as an electrical 1/4-wavelength radiator. It also generates enough capacitive reactance to produce another discrete resonance at about 11 MHz. The second, 40 meter L/C circuit generates enough reactance to resonate the whole HF9V allowing it to act as a 1/4-wavelength radiator. In order to minimize conductor and I²R losses on 80 and 40 meters where the antenna is physically shorter than a 1/4-wavelength and thus operates with lower values of radiation resistance, large-diameter self-supporting inductors and low-loss ceramic capacitors are employed. Where the height of the HF9V is slightly greater than a 1/4-wavelength on 30 meters, an L/C series tuned circuit taps onto the 40 meter coil for the extra inductance to pull the earlier 11 MHz secondary resonance down to 10 MHz. At the same time, a portion of the 40 meter coil is shorted out which allows the circuit to resonate on 30 meters The addition of this circuit also produces additional resonances at 14 MHz and 28 MHz. On 20 meters the entire radiator operates as a 3/8-wavelength vertical with much higher radiation resistance and VSWR bandwidth than conventional or trapped antennas having a physical height of 1/4-wavelength or less. Because the 20 meter radiation resistance will be several times greater than that of conventional vertical antennas, an electrical 1/4-wavelength section of 75 ohm coax is used as a geometric mean transformer to match the approximate 100 ohms of feedpoint impedance on that band to a 50 ohm main transmission line of any convenient length. The HF9V operates as a slightly extended 1/4-wavelength radiator on 15 meters, a 1/4-wavelength stub decoupler providing practically lossless isolation of the upper half of the antenna on that band. On 10 meters the HF9V becomes a 3/4-wavelength radiator with considerably greater radiation resistance and efficiency than 1/4-wavelength trapped types. On 17 and 12 meters the coils act as packets of reactance which allow the entire radiator to operate as a 1/2-wavelength or 5/8-wavelength vertical. Capacitance for these circuits comes from what exists between the windings, the radiator and the capacitance hat. On 6 meters the vertical wire, together with the adjacent section of antenna, form a short-circuited 1/4-wavelength transmission line which cancels current flow. At the lower, open end of the 1/4- wavelength section a very high impedance is created the effectively divorces the upper part of the antenna leaving the lower section to radiate as a 3/4-wavelength vertical."