[DSP-10] KDSP-10 interface module

[dsp-10@mailman.qth.net]

Hi John,

I decided to populate all of these parts so that I could test the board
before it was mounted in the shielded enclosure.

Everything fit ok except that I had to remove the push on plastic cap of
the power switch and keep the board close to the side of the enclosure
opposite the feed though capacitors.

It is a good engineering practice to plan the use of the wiring to the
feedthrough capacitors to keep the DAC and ADC signal leads as short as
possible to reduce the possibility of cross talk noise pickup. Note that
the DAC output leads are passed through two 10mH RF chokes then to the
feed through's. This means that the DAC and ADC go to the left of the
enclosure viewed looking at the feedtrough's.

I kept the Power and RS-232 signals to the right side of the enclosure.

I used the spare feedthough to carry the Flag signal to a conditioning
circuit using a NPN transistor and capacitor to remove the high frequency
square wave component to drive a LED mounted on the outside of the die
cast box above the 12V power input jack. this comes in handy to let me
know the status of the board. I found that sometimes the software did not
always initialize the DSP.

I do not think that I will ever remove the board to use it outside of the
enclosure so that it is strictly a matter of preference to install the
DB-9 connector etc on the DSP board.

Hope that this helps

GL 73

Bob Johansen WB2SRF