Power Test of HB9ABX Antenna
1st. November 2005

Power test in SSB of the new HF antenna

Many OMs have asked me, if the antenna is able to support
high power operation, as all tests were performed with 100 W.
These questions were answered with the comment, that I
think so, as the construction should allow high power
operation, but it was not tested so far.
Today, November 1st, tests with high power were performed.

Tested antennas:
20 m = 1.3 meter radiator length
40 m = 1.6 meter radiator length
installed on top of the car (Honda Accord)

Location of test site:
Parking place between houses in the village
Allschwil close to Basel.

The following equipment, all inside the car, was used:
Transceiver: TS-50 connected to 12 V car battery
Linear: Kenwood TL-922 connected to 220 V AC line
SWR/Power Meter for 2000 W: Drake WH-7
NO Tuner, as antenna provides directly  50 Ohm

The maximum power delivered to the antenna was
1200 W, limitted by linear amplifier.
The SWR remained at full power at 1.0
and comparing reports from the remote side indicated
2 S-points or roughly 10 dB difference between linear ON
and linear OFF.

No arcing or other flys appeared, and looking in dark
night: completely clean.
Some warming of antenna elements was noticed, but
presenting absolutely no problem for 1 KW operation,
if appropriate material is used.

The modulation was reported as cristal clear, what
indicates that no unlinearity appears despite of
the high power operation.

Operating experience:
It makes fun, to receeive a  S9 report to the first
CQ call on 20 m from Canada (at 16h afternoon).
Then followed a few contacts with UK, Scotland,
and Sweden, all reports between S9 to 9+20 dB.

On 40 m a few QSOs followed with Spain, Austria,
and Portugal (Madeira), whereby several tests
with/without Linear were made.
The received report in all QSOs was S9 and better.
The 1 KW operation was noted by significant reduction
of nearby QRM and splatter.
Also the remote antenna adjustment was tested in the
1 KW operation. Each frequency of the band could be
set to SWR 1:1 within five seconds.

Conclusion:
The construction guide will specify exactly, what has
to be observed for safe 1 KW operation.

Remarks:
The car electronics reacted to the high power.
With open doors, the headlight control switched on and off,
triggered by the RF power.
This effect disappeared when ALL doors were closed.

With best 73s

Felix HB9ABX


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