[DSP-10] Initial turn on

[emil switzer]

Hi All,

Just finished the PCB for my dsp-10 and have seen a few things that puzzle
me on initial turn on.

I am applying 11 VDC to the unit with the pcb still out of the case.

1. When I first power on the unit only the amber light comes on and it
draws about 150 mA of current. In this mode both the +10TX and +10RX
voltages are zero. Pins 1 and 2 of U108 are also both zero in this mode. It
seems that if I leave the unit powered up like this for a while and then
cycle the power the red LED comes on along with the amber and both +10TX
and +10 RX are present at 10 volts. The unit draws 350 mA at this
point.Also all the Q outputs from U108 are high.

My question is this normal or is there a problem here?


2. The voltage readings at the source of Q101 is 1.85 volts (vs .23 in the
assy manual) and source of Q4 VCO reads 1.35(vs .91)

Are these close enough to continue or is there a problem here?


3. The voltage readings are off on U105 and U106. Reading 2.3 volts on U105
and 3.8 volts on U106. All resistor values look right and there is +10
coming into F103 and the 3 paralled resistors. Should I relace these?
Dosn't seem like anything else in the circuit should effect these values
except the MMIC's.

Any help or comments would be appreaciated.

73
Emil
W1GGM/6