Re: 10W Linear RF Amplifier

by **admin** Thu Nov 14, 2019 6:48 pm

I know that this post was a little while ago, but here is a response:

1 - The amplifier works well down to about 3.5MHz, so in principle you can quadruple (x4) all the number of turns, but use a larger former to accomodate the wire.
The transformers are a compromise between high inductance (affects low-frequency response) and inter-turn capacitance (affects upper frequency response).

2 - A better PA for medium waves can be a push/pull or complementary audio amplifier, but with the frequency-limiting components removed.
With a 30V-0-30V DC supply to the amplifier you would have 20V RMS, or about 8 Watts of power, without any transformers. All you would need is a band-pass filter at the antenna.

If you used the same, but with a 1:2 balun (a centre-tapped coil) then you could get up to about 30 Watts.

So there are two suggestions for you. I know which one I would choose to use for LW (200kHz-ish) or MW (900kHz-ish)

BR Harry - EA/SM0VPO

by Artime123 Tue Sep 17, 2019 7:22 pm

HI all,
we (EC2ALV and EA2DE) are planning to use this Amp. as a BC Band transmitter. AM BC Band stations are slowly and steadily fading away, leaving our restored BC band radios without means for testing performances and demos.
What we would like to hear is any comment/suggestion before we begin cutting the board or winding up toroids! Thanks.
Regards,
Félix (EC2ALV)