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Audio amp for QCX #chat


Steve in Okinawa
 

Did you have a load on the amplifier? Try it with a small speaker. If the cw reception is ok for you, you've achieved what you need. I use one and don't expect hifi ssb reception :)

Steve Fabricant


Al Sines
 

Thanks Steve. Yes I had an old Motorola mobile speaker connected while looking at the output.  I intend to use it since it meets all my requirements was just curious about class D amps and the “ugly” oscope display. 

Alan


On Apr 12, 2018, at 18:36, Steve in Okinawa <sfab43@...> wrote:

Did you have a load on the amplifier? Try it with a small speaker. If the cw reception is ok for you, you've achieved what you need. I use one and don't expect hifi ssb reception :)

Steve Fabricant


Alan G4ZFQ
 

So my question is can someone tell me a bit about class D audio amps?
Alan,

Google can help, lots of information like https://en.wikipedia.org/wiki/Class-D_amplifier

73 Alan G4ZFQ

Attached are three screen shots from my oscope there is one that shows no input in fact this is what I get with the input shorted to ground. The other two show the output at a low level and then the output at a moderate level.  At a high level it gets very ugly.  Not sure what I am seeing.  I expected to see something that resembled a sine wave.
The amp works well, doesn't get hot, draws very little c


Alan G4ZFQ
 

Google can help, lots of information like https://en.wikipedia.org/wiki/Class-D_amplifier
And note the potential for QRM, maybe you will not see anything but you could.

73 Alan G4ZFQ


Peter
 

I have successfully used this kind of amplifier bought here in Poland, very cheap. It draws on 20mAmps in standby mode and about 200-300mAmps fully driven. No significant distortion. You could simply supply it fro 5 Volts stabilizer. There are also mono versions. Remember you can not simply bridge D class amplifiers... Here is one mono http://allegro.pl/modul-wzmacniacz-audio-5w-2-6v-xpt8871-avr-arduino-i6798235475.html


Peter
 

https://drive.google.com/open?id=1CSSM6IN-A7ZDdw5ijkrZiVAnKpd0qUSY
PAM8302 2.5 watt Class D audio amp with IKEA plastic cup.