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Re: LF: Effect of LP-filter om efficiency

To: [email protected]
Subject: Re: LF: Effect of LP-filter om efficiency
From: [email protected]
Date: Tue, 8 Jun 2004 05:52:54 EDT
Reply-to: [email protected]
Sender: [email protected]
In a message dated 08/06/2004 08:22:21 GMT Standard Time, [email protected] writes:
So it seems to me that class D and E amplifiers should preferably be followed by a low pass filter with a series inductor at the transmitter side.
Please correct me if my conclusion is not valid.

An interesting question is whether a low pass filter is really necessary when the transmitter feeds the aerial via a series tuning coil.
Hello Dick.
A brief response is that all the inductor input LPF circuits I have tried have either casused instability or fatal (for the FETS) voltages at the PA.
I did try your idea of no LPF in the early days of 73kHz,  and managed to get a very nice 577 report from an amateur 2 miles away on 20m.
David  G0MRF
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