Message-ID: <002801ce039a$adff7510$0401a8c0@xphd97xgq27nyf>
From: "mal hamilton" <g3kevmal@talktalk.net>
To: <rsgb_lf_group@blacksheep.org>
References: <CAKvcm2edSxcESuKJR6yux7M-pBXE63rUVPbE98M-L6Mb8--cLg@mail.gmail.com>
Date: Tue, 5 Feb 2013 12:16:51 -0000
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Subject: LF: Re: My transmit converter description
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Dimitris
Your 'scope shot of the signal after the low pass filter shows a Voltage
spike which should not be there for a class E amplifier. This needs to be
smoothed out otherwise you wil eventually Zap the PA Fet.
You need to adjust L2 to correct this problem.
de Mal/G3KEV

----- Original Message -----
From: "Dimitrios Tsifakis" <dtsifakis@gmail.com>
To: <rsgb_lf_group@blacksheep.org>
Sent: Tuesday, February 05, 2013 12:50 AM
Subject: LF: My transmit converter description


> Hello group,
>
> My transmit converter is now finished and tested - it survived two
> sessions of 50% duty cycle WSPR transmissions on 475 kHz and the
> results are great. I thought others may find this useful, so I have
> put a write-up on my web page:
>
> http://people.physics.anu.edu.au/~dxt103/472/nltt/
>
> It is a 50 W class-e PA designed for 50 ohm impedance, so there is no
> need for an impedance transformer. Doesn't get simpler than that :-)
> The driving circuit is based on G3XBM Roger's design with the
> difference of a 10 MHz OCXO LO and the addition of a beefy MOSFET
> driver.
>
> 73, Dimitris VK1SV
>