Krystalka s fetem

Krystalka s fetem
Vydáno dne 05. 12. 2007 (454 přečtení)

Ramonovy zkušenosti ze stavby (v anglickém originále!)

Novy2 Hello,

I tested the MOSFET ALD110900A with a frame (loop) antenna wound on a 22cm x 22cm cross- section cardboard (carton) box. I used 20 turns of plastic insulated stranded copper wire AWG 22. A polyvaricon (plastic insulated 365pF variable capacitor) was used for tuning in stations. Couldn´t couple conveniently the frame antenna to the ALD.The coupling turn (or turns) would load down the frame tuning circuit.

On the other hand, the frame antenna wound on a cardboard box proved being a great performer for a simple crystal radio using a conventional germanium diode. The only concerns worth taking into account are that the diode should be a carefully selected one for sensitivity, the use of an audio matching transformer is a "must", magnetic earphone elements from old telephones of the 80's yield better sensitivity than the common piezoelectric ceramic earphones, even when impedance matched.

I am now working on a 44cm x 30.5cm cross-section loop antena, also wound on a cardboard box.

Last night I tuned 8 stations 10~15km from my home, 10kW to 35kW with a 22cm x 30.5cm frame antenna (23 turns gave 340uH for a 260pF variable capacitor). Looks promising playing with these frame (loop) antennas for MW listening. It is a pity that NDB (non-directional beacons) LW stations were shut down in my country. Listening to them with a 2m x 2m loop would have been a nice experience. Am I correct?

Very best regards,

Ramon

( Celý článek | Autor: Krysatec | Počet komentářů: 1 | Přidat komentář |

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