To: | [email protected] |
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Subject: | Re: LF: Re: 472 kHz PA running at 12 VDC |
From: | [email protected] |
Date: | Thu, 28 Jun 2012 15:50:34 +0200 |
Reply-to: | [email protected] |
Sender: | [email protected] |
and me too, Stefan
tks in adv Uwe/dj8wx Von: [email protected] Gesendet: 28.06.2012 12:49 An: [email protected] Betreff: LF: Re: 472 kHz PA running at 12 VDC Stefan, me too, pse. 73 Walter DJ2LF ----- Original Message ----- From: "Stefan Schäfer" To: Sent: Thursday, June 28, 2012 12:33 AM Subject: LF: 472 kHz PA running at 12 VDC > 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 > > |
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