[DSP-10] RA30H1317M based brick amplifier

[Lee Scott - AA1YN]

Hi All,

I finally got my RA30H1317M based amplifier up and running.  Quite simple 
circuit with no voltage monitor nor low pass filter on the output.

I had to put a 3dB attenuator on the input of the amp to make the DSP-10 
look resistive 50 ohms. without the attenuator, the amplifier oscillated 
which makes me think the RA30 does not like reactive inputs.  I suspect 
that a 1 or 2dB pad using SMT resistors on the input would do. It just 
isolates the device from the 2 pole low pass filter on the DSP-10 output.

I tried shielding the device only to make sure there was a good RF ground 
between the device and the PC board.  Not really trying to shield it. The 
device still had the oscillation problem which is why I went to an attenuator.

I used an LM2941 regulator for setting the bias voltage and using that, I 
set the idle current to about 4 amps.  I use the on/off pin on the 
regulator to switch it into transmit mode via the DSP-10 amp control 
(buffered with a BS170).  The amplifier works like a champ.  I'll see if I 
can put up some photos and a write-up on my website sometime in the near 
future.


Lee Scott - AA1YN http://www.aa1yn.com
Home of the VHF & Up Register http://www.aa1yn.com/vhf
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Hooksett, NH
FN43gc52