Hi Rik,
OK, a picture tells more than 1000 words:
https://dl.dropboxusercontent.com/u/19882028/ULF/ULF_MF_Diplexer.jpg
While drawing the picture i saw that i had to correct my idea. The
transformer should be in series and i have to think about the lower
series C. Another thing is that the MF transmitter should act as a
shortcut for ULF so the transformer does not act as a (saturated) L. So
the picture is updated.
73, Stefan
Am 26.08.2016 14:36, schrieb Rik Strobbe:
Hi Stefan,
if you can keep both transmitters from feeding power into each other it should
work.
But one thing to keep in mind is that the 2nF parallel capacitor needed on ULF
will reduce the overall (antenna + parallel C) resistance at 475kHz
significantly.
It is not clear to me what configuration you intend to use, but maybe you
should try to avoid that the 2nF cap is drawing a lot of 475kHz current.
73, Rik ON7YD - OR7T
________________________________________
Van: [email protected]<[email protected]> namens
DK7FC<[email protected]>
Verzonden: vrijdag 26 augustus 2016 13:46
Aan: [email protected]
Onderwerp: LF: A simple ULF/MF diplexer?
Hi all,
I would like to run some transmissions on MF WSPR but i also like to run
a longer transmission on 2.97 kHz. In the current ULF TX installation
i'm using a parallel 2 nF capacitor anyway. This is just -j167 Ohm on
MF. I could series compensate it with 65 uH (which is just j1.2 Ohm at
2970 Hz :-) ) to ground. The 65 uH could be parallel compensated for MF,
using 280 nF. Then i could add a ferrite transformer to apply the MF RF
across the 65uH/280nF parallel circuit. The large loading coil of 1.3 H
will be a high impedance, hopefully, as long as there is no internal
resonance on MF due to its own winding capacity.
The 2 nF capacitor will have to handle the sum current of ULF and MF.
QRO is not possible on MF i think but it will handle a few watts which
is fine for WSPR. Hmm, worth a try?
73, Stefan
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