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Re: LF: PA problem

To: [email protected]
Subject: Re: LF: PA problem
From: DK7FC <[email protected]>
Date: Fri, 10 Nov 2017 20:35:44 +0100
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Am 10.11.2017 19:44, schrieb N1BUG:
I see a nice clean sine wave at the other side of the LPF.
With a good LPF, the output often looks quite good on a scope, even with massively distorted input signals.
But I see a lot of RF (36 volts peak to peak) at the +13.8V power connection to the PA!
Yes and your power supply doesn't like it, it can be damaged from the high RF peak currents. Or the voltage regulator can do crazy things. And BTW the current measurement is likely to be totally wrong with such an AC component. With the coil you can decouple the AC component from the supply, at least most of it. Just take a piece of enameled cu wire, 1mm diameter, and wind a coul with 15 turns on something with 15mm diameter. Or use a T106-2 core for example. Of course the big C is needed as well. For the 1 uF cap i would use WIMA MKP-10 or so. Without calculating i would say that this improves things significantly.
73 and have fun,
Stefan

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