Stuart Longland wrote:
[Previously sent to rec.radio.amateur.equipment by mistake... resent
here]

Hi all,

I was wondering if anyone knew of a solid state 2m linear amp project
that I could build. I'm looking for no more than about 30W. It'll be
primarily used for FM, driven from my handheld radio. Bonus points if
it can do 70cm too (or at least allow pass-through unattenuated...).

Most of the designs I've seen are for tubes with an output power in
the KW-range... my radio license only allows me to transmit 30W FM or
100W SSB... so these are massive overkill (and not desirable for other
reasons).

The only project I've seen that fits the bill so far is
http://www.falara.org/tektalk/GPOAmp.html which calls for a PCB made
with G10 stock. I have no idea where to obtain that here in Brisbane,
I have some blank PCB, but have no idea what grade it is, or how much
impact on performance using it would have. The MRF1946A is also
difficult to source.

Does anyone know of a good project to start on this sort of thing?

Regards,
Stuart Longland (VK4MSL)

You can homebrew a very simple amp that should meet your specifications...

A generic PC board can be found at http://www.rfparts.com/pcb.html
and I would recommend part number DEM2330. There is a link to "View a
pdf of the DEM2330 Instruction Sheet." You could build everything as
they show in the instruction sheet (which is for a 1300 MHz amp) and
just substitute the RF module with the Mitsubishi RA30H1317M module for
2M or the RA30H4045MR for 70cm. The data sheets for the modules are at
http://www.rfparts.com/module_sau-sav.html#ra and there are also more
module choices there. Both modules specify an input power of 50 mW
maximum, so you would need an attenuator (pi type is easily done by
cutting a break in the input lead on the circuit board and installing
the correct resistors around the cut). If you have 1.5W from the HT,
you would need about 16 dB of attenuation. You would need a pair of RF
relays, one at the input and one at the output to route TX signals
through the amp on TX and bypass around the amp during RX.

Good luck with the project!

73,
Scott
N0EDV