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LF: A simple ULF/MF diplexer?

To: [email protected]
Subject: LF: A simple ULF/MF diplexer?
From: DK7FC <[email protected]>
Date: Fri, 26 Aug 2016 13:46:23 +0200
In-reply-to: <[email protected]cal>
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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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