
Theory Of
Operation:
The first (lower) L/C circuit generates enough reactance to
bring the whole HF9V to resonance on 80 meters allowing it to act as a
1/4 l 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
l radiator. In order to minimize
conductor and IČR losses an 80 and 40 meters where the antenna is
physically shorter than a 1/4 l and thus
operates with lower values of radiation resistance, largediameter,
selfsupporting inductors and lowloss ceramic capacitors are employed.
Where the height of the HF9V is slightly greater than a 1/4
l 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 l
vertical with much higher radiation resistance and VSWR bandwidth than
conventional or trapped antennas having a physical height of 1/4
l or less. Because the 20 meter
radiation resistance will be several times greater than that of
conventional vertical antennas, an electrical 1/4
l section of 75ohm coax is used as a geometric mean transformer
to match the 100odd Ω of feedpoint impedance
on that band to a 50 Ω main transmission line
of any convenient length. The HF9V operates as a slightly extended
1/4 l radiator on 15 meters, with a 1/4
l 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 l
radiator with considerably greater radiation resistance and efficiency
than 1/4 l 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 l or 5/8
l 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
shortcircuited 1/4 l transmission line
which cancels current flow. At the lower, open end of the 1/4
l section, a very high impedance is created
that effectively divorces the upper part of the antenna leaving the
lower section to radiate as a 3/4 l
vertical.
Tuning:
After constructing and erecting the HF9V, you will need to
tune the antenna to resonance on each of the nine bands. This is
accomplished by adjusting the length of the coils, wires, and tap
position. Reference to the diagram at the tope of this page in
conjunction with the instructions on pages 8, 9 and 10 of the
instruction manual will assist in this chore.
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.
(Vertical antennae are inherently unbalanced and do not require a
balun.)
VSWR at resonance: 1.5:1 or less all bands
Bandwidth for VSWR of 2:1 or less: 1 MHz @ 6 meters
entire band @ 10, 12, 15, 17, 20, 30 meters
250300 kHz @ 40 meters
40100 kHz @ 75/80 meters
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 ft2
(.2 m2) 
