-11-
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 a 1/4
8
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
8
radiator. In order to minimize
conductor and I²R losses an 80 and 40 meters where the antenna is physically
shorter than a 1/4
8
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
8
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
8
vertical with much higher radiation resistance and VSWR
bandwidth than conventional or
trapped
antennas having a physical height of 1/4
8
or less. Because the 20 meter radiation resistance will be several times greater
than that of conventional vertical antennas, an electrical 1/4
8
section of 75-ohm
coax is used as a
geometric mean
transformer to match the 100-odd
S
of
feedpoint impedance on that band to a 50
S
main transmission line of any
convenient length. The HF9V operates as a slightly extended 1/4
8
radiator on 15
meters, a 1/4
8
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
8
radiator with considerably greater radiation resistance and efficiency than 1/4
8
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
8
or 5/8
8
vertical. Capacitance for
these circuits comes from what exists between the windings, the windings and
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
8
transmission line
which cancels current flow. At the lower, open end of the 1/4
8
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
8
vertical.
ELECTRICAL AND MECHANICAL SPECIFICATIONS
Height (adjustable): 26 ft (7.9 m)
Shipping Weight: 14 lbs (6.3 kg)
Feedpoint Impedance: Nominal 50 ohms through included matching line.
VSWR at resonance: 1.5:1 or less all bands
Power rating: 2 kW PEP 75/80, 40, 20, 15, l0 meters; 800 W PEP 17, 12 meters;
500 W PEP 6, 30 meters
Wind loading area: 2.2 ft
2
(.2 m
2
)
Bandwidth for VSWR of 2:1 or less: 1 MHz 6 meters, entire band 10, 12, 15, 17,
20, 30 meters, 250-300 kHz 40 meters, 40-100 kHz 75/80 meters
Summary of Contents for HF9V
Page 14: ...14 Feedline Detail PICTORIAL...
