Christian Groeger
-------- Originalnachricht --------
Betreff: Re: LF: MF PA
Von: "C. Groeger" <[email protected]>
An: [email protected]
Cc:
Hi Stefan,
Thanks for these infos!
This is always helpful because I'm not a really good technican. Everything I
built was a mixtiure of my ideas and stuff from the net...
Output power is 100 w, measured with a 100 w bulb, matched to 50 ohms via
transformer. Thus efficiency is ok, I think.
The overall setup is:
Vxo/xo 10 mc/10.24 mc, mixer, Fd,
PreDriver 2n2219, Driver irf640, pa 2 x irf 540.
I have attached a foto...
73, df5qg
Christian Groeger
Stefan Schäfer <[email protected]> schrieb:
>Hello Christian,
>
>Am 10.09.2012 10:05, schrieb C. Groeger:
>> Hi Stefan!
>> I don't know the problem yet. Maybe these small fets went to hot.
>> My pa design is very simple, 2 x irf 540 parallel in class D, transformer to
>> 50 ohm, Pi filter and variometer.
>> Operating voltage was 12 V only but nevertheless resulting an Input of 120
>> watts.
>>
>The advantage of a homemade PA is that you normally use cheap and easy
>available parts which are easily replaceable. The IRF540 costs about 0.6
>Euro so that's all not so dramatic at least.
>
>OK, 120W input power at 12V DC in class D mode. But what was the output
>power? Class D, so it is hard switching with a rectangular gate voltage,
>cfm? What is the driver you're using to drive the FETs?
>
>If the driver is strong enough to provide good switching times even at
>high input Cs then maybe a IRFZ48N or better an IRFP064N may be a better
>choice at 12 V DC. They are all cheap and available at Reichelt, you know...
>
>Here, i'm using this PA design:
>https://dl.dropbox.com/u/19882028/MF/100W%20475kHz%20PA.png and
>https://dl.dropbox.com/u/19882028/MF/DK7FC%20472%20kHz%20PA%2015W%2B100W.JPG
>
>73, Stefan/DK7FC
>
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