On Mon, 03 Apr 2006 21:12:59 +0800, Richard Hosking wrote:

Dear all
I want to build a power amp for SSB HF 1.5-30 MHz Specs
approx 5W out
Cheap/easy to source components
Surface Mount parts/small
Rugged/stable into any/most loads
Gain around 40 dB
Flat gain to 1 dB or so

It is hard to beat CB PA and driver transistors for this job.
2SC2166 makes a great driver. If you only need 5W, you could
use them as the final stage. For slightly higher power levels,
the 2SC1969 or 2SC2312 are a good choice. The 2SC1945 is particularly
attractive because the HS tab is connected to the emitter rather
than the collector. Genuine Mitsubishi are usually better than
unbranded generic transistors. http://www.grandata.co.uk usually
have the best prices for Japanese transistors.

Thought I would do something like

Class A MMBT2222 - 2X push pull MMBT2222 - finals push pull balanced

What to do for the finals?
I looked at the PD55003 RF MOSFETS - can you get these easily? Will they
work down to HF?

My experience with modern devices is that you can easily
get them for free as samples but you can't buy them for
love nor money :-)

The Philips BFGxxx series of surface-mount transistors are readily
available on this side of the planet.
BFG235 12V 2W and BFG135A 15V 1W have multi-GHz ft and
are available from Maplin.

What other issues?

Don't let the smoke out.

What about transformers?

Broadband ferrite.

Is this a practical proposition?

Yes.

I havent seen any similar designs

Thats because we are all using CB transistors.

BTW, It is nice to see you back on r.r.a.h We all missed you.

73, Ed. EI9GQ.

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