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Re: LF: 472 kHz PA running at 12 VDC

To: [email protected]
Subject: Re: LF: 472 kHz PA running at 12 VDC
From: DK1IS <[email protected]>
Date: Thu, 28 Jun 2012 12:30:19 +0200
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Am 28.06.2012 00:33, schrieb Stefan Schäfer:
MF,

For the homebrewers, here is my prototype of a MF class D PA that operates at 12 V DC. Input frequency is divided by 4, so a normal HF TRX can be used (set to 160m / 1.9 MHz) to drive the PA. The input power must not exceed the range of 1...4 watts. The output power can be switched in 2 steps between ~15W and up to 100W, depending on the output impedance and input voltage (10...15V). The output impedance is not so critical, Z=R may be in the range of 30 Ohm to infinity. The FETs are IRFZ48N types, the driver is a ICL7667CPA. The transformer uses RF litz wire, 30x0.1mm diameter. I didn't spend to much effort for optimising the efficiency, not at this power level. During a CW QSO or longer calls at 50 W RF power the heat sink (which is just a 3mm thick Al plate) becomes hand warm. The measured efficiency is 88 % at 18W RF power and 80% at 50W RF power. The needed power for the driver circuitry is included in this measurement.

If someone is interested i may convert the circuit from my mind into a schematic as a png file.

73, Stefan/DK7FC

https://dl.dropbox.com/u/19882028/MF/DK7FC%20472%20kHz%20PA%2015W%2B100W.JPG


.

Hi Stefan,

me too, please!
73,
Tom,DK1IS



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