[A-DX] Unerwünschte Mischprodukte bei Wellbrook ALA1530

[Wilhelm Hombach <wh.bonn@xxxxxxxxxxxxxx>]

Hallo Liste,

es geht weiter im Thema:

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Dear Andy,

many thanks for your superfast answer to my mail. I would discuss your
idea of a capacitor parallel to the antenna ring. As I calculated the
aluminium ring has a inductance of about 31,8 mikroH. Connected to the
50 pF in parallel we`ll get a resonance on around 4 MHz.

I understand that the ALA is an aperiodic system which has a very
small input resistance across a huge frequency range. Transforming the
system to periodic will unmatch the resistance between antenna (very
high on resonance frequency) and amplifier (very low and aperiodic).

I suggest two solutions. The first solution is to have a low pass
filter or some FM-tuned serial resonant circuits in front of the front
amplifier; second solution is to decrease the diameter of the ring, so
that the 1lambda lenght is above the FM-band.

I have two additional questions:

Is the aluminium ring a electric shield and the antenna is inside this ring?

Is it possible to remove the ring without damaging the antenna?

Greetings from Bonn
Wilhelm, DL4KAL

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Sent from Bonn, NW, Deutschland
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