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Showing posts from April 5, 2011

Made an active antenna to compare

Image
To compare with the K9AY loop i made a small active antenna  
to the concept of PA0RDThttp://yu1lm.qrpradio.com/pa0rdt%20whip.pdf
I used a strip of double sided copper  clad  epoxy print 200x30 mm.
The amplifier is a FET  U310  and  2N3053 emitter follower.


This small capacitive antenna  did fit in a cycle bidon (bought on the Alp de Heuz once..) 
Interesting this antenna  is only picking up the Electrical-field. 
It is also a good RFI sniffler.


I used a relative big pickup plane of about 3x20cm  at the risk of IMD but i wanted to compare this E-field antenna on the 137kHz and 500kHz bands.








It works but the DCF39 TX at 138.9 kHz is about 30B stronger on the K9AY Loop. I have to check that out the difference should not be that big.
That was at the low position (top picture).
I moved it on top of the house about 8m a.g.  
Now DCF39 138.9 is s9+30   the difference is about 20dB in disadvantage against the loop. The high position gave 10dB more signal. I have heard OK2BVG good on 502kHz.
The higher b…