Jim, LF,
I'll try to go on as fast as the distributor and ebay did ;-) So this is
the current situation:
Decided to use the 2x7 bundle. The cross section area of 7 pcs. just
lokks better :-) Also the complete stick is much more handy and robust.
Markus/DF6NM gave me the hint to overlap the inner rod by 50%. So i
intentionally broke one rod and put the 2 halfs to the inner ends. One
complete one is now in the inner center.
See: http://dl.dropbox.com/u/19882028/LF/ferrite%20antenna%20parts.JPG
I took a simple bonding tape to isolate the rods from each other. The
whole arrangement was fixed by bonding tape and put into a stable and
very proper PVC tube with 2.5 mm thickness, making the rod very robust
and give some distance between winding and ferrite (just as in the magic
antenna article ;-) ).
Ther was even some place to add a bit of that transport foil with the
air bubbles inside, you know ;-) Perhaps this will be some kind of shock
protection (hopefully never needed) and fixed the rods inside the tube.
http://dl.dropbox.com/u/19882028/LF/inside.JPG
Now the outer dimensiona are 285 mm x 33 mm.
As a first test i wound a simple wire arround the rod, 22 turns.
Resonance C is 11.2 nF and f res = 137,1 kHz. Q = 100 (unloaded). During
the measurement i was irritated by a strange peak near 137.7 kHz which
was my own transmission during that time ;-)
So L must be 120 uH. Not so much...
Will go on now using the Litz wire and start with about 40 turns and see
what comes out. Then i go for 60 turns, maybe 80 if Q is still rising.
73, Stefan/DK7FC
Am 16.08.2011 19:01, schrieb James Moritz:
Dear Stefan, LF Group,
----- Original Message -----
The 20 mV is the peak level (thus mVp ;-) ) while the mentioned 100
uV is rms.
OK - so that makes your RX noise level 3dB lower, and gives you 3dB
more margin, which is good!
Cheers, Jim Moritz
73 de M0BMU
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