The Kellermann-Balun is named after Mr. Helmut Kellermann,
DJ2IP, who did the development. This is described in detail
in an article in the german magazine "Funk", no. 12/2001 (in
german language).
The Kellermann-Balun is a coax-balun which is distinguished
by a high imbalance suppression accompanied by a very small
capacity between input and output. The high attenuation
of 60 dB at 2 MHz and still 40 dB at 50 MHz is performed over
the frequency range from 1.5 MHz to 50 MHz.
For many radio amateurs it is impossible to erect a good antenna
like a beam antenna on a tower. The compromise quite often is a
dipole with an open two-wire feeder, which should work on all shortwave
bands. To make the antenna work on all frequencies it is
absolutely necessary to match the antenna impedance to the output
impedance of the transmitter. This is always possible with a L-circuit
consisting of an inductor and a capacitor. After the transformation of
the antenna impedance to 50 Ohm a balun is necessary, which has a
sufficiently high imbalance attenuation, especially if the antenna
impedance is high like 2K-Ohms.
With the Kellermann-Balun it is possible without any problem
to tune a real symmetrical antenna system with a two-wire
feedline using an asymmetrical tuning circuit. Until now usually
a real symmetrical tuning circuit was used, which is more complicated
and expensive. The high impedance of the Kellermann-Balun prevents
any imbalance in the antenna system and isolates the tuner from
the transmitter.
Such a balun is also called an imbalance attenuator. Imbalanced
antenna currents can be caused by an asymmetry of the antenna
system. This can cause a current flowing in the shield of the
coax cable searching a way back to ground through the transmitter,
which in some cases leads to problems if the transmitter is not
sufficiently grounded. The Kellermann-Balun prevents these
imbalance currents by its high imbalance attenuation.
Technical Data:
Impedance: 50 Ohm
Inductance: 530 uH
Capacity input-output: < 10 pF
Imbalance attenuation:
at 2 MHz 60 dB
at 10 MHz 50 dB
at 20 MHz 45 dB
at 30 MHz 40 dB
at 50 MHz 40 dB
Maximum Power: 1 KW PEP
Dimensions: LxHxW 295 x 80 x 50 mm
Weight: 1.350 kg
Temperatur Range: -20 to +80 C
Coax Cable used: RG58CU
Length of input and output leads: 0.3 m
High Power Version KB-1000-T
Now we offer a High Power Version of the Kellermann-Balun for a maximum power
of 5 KW PEP. This version is made with Teflon-Coax-Cable RG400U instead of RG58CU.
All other specs are identical.
Prices
Type
Price incl. VAT
Price w/o VAT
Kellermann-Balun KB-1000
95,20 Euro
80,00 Euro
Kellermann-Balun KB-1000-T
122,69 Euro
103,10 Euro
All prices plus postage.
The Kellermann-Baluns KB-1000 und KB-1000-T are immediate available!
