Wednesday, February 10, 2010

600m RX loop

I did find some left over energy to finally build/finalize an aerial for the 600m band.

This is what I came up with....

 

This thing is about 80cm wide, uses 4 turns of 2x2.5mm² heavy duty speaker wire (a length of about 10m), resulting in 8 turns. The loop is resonated by a 2x130pF polyvaricon in parallel configuration, i.e. 260pF, parallel with a 680pF ceramic capacitor.
Have a look:

 
RF is coupled out by means of a (unknown) toroid, used as a 4:1 transformer.
This aerial resonates from 480k/c to 540k/c.
For the time being, I will spare the precious "HF-Litze" (translate: radio-frequency Litz wire) for more elaborate projects.

2 comments:

  1. Given the price for the Litz wire , saving it for later is wise, I think.

    I would probably have made this one with two more turns and then saved on the parallel capacitor, but the frequency range fits the needs well.

    How is the performance ?

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  2. I can't yet say anything about the performance yet. When trying to find the matching parallel capacitance, I was tuning in the B.C. band and could see some severe resonance effects.

    Due to the heavy gauge and weight of the material, more turns will make the thing really heavy...
    A capacitance of about 1000pF +/- seem normal for MW loops.

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