Troubleshooting:
Hopefully, your rig performed flawlessly during the above tests and calibration. Unfortunately, this is not always the
case. Specific trouble shooting advice is hard to give, the best we can do is go over some basics.
99.99% of the time, the reason a kit does not work is due to soldering issues. Therefore, this is the first thing to look
for. Forgetting to solder one end of a chip resistor or cap is a common mistake. Sometimes, if a component is missing a
solder connection, everything might seem to work alright at first, but then a problem shows up later after the board has been
handled some. Twisting the board slightly can often make this kind of problem appear and disappear. A bad or missing solder
connection to one or more of the 0603 pull up resistors for the MPU input pins can make it act strangely or lock up all
together.
Sometimes an IC pin looks to be soldered, but the solder is just on the top of the lead and isn’t actually connecting
to the board pad. One way of identifying this problem is the “wiggle” the lead with the tip of an Xacto blade and see if it
moves or not.
If the problem is not obvious from a simple visual inspection, try to localize the problem area. This is preferred to
taking the “shot gun” approach of re-soldering everything. If all you have for test equipment is a DVM, you can only do a
limited amount of troubleshooting. Ideally, you will have a ‘Scope and a signal generator available for more intensive
troubleshooting. If you don’t own a “Scope, maybe you can find someone local with one who would be willing to help you out.
When using a voltmeter or other probes on the 3.5 and 5 V regulator pins, be very careful. The input and output pins are
adjacent, so there is a real possibility of shorting these together. If this happens and the raw DC is put on the regulator
output, it will most likely fry all the ICs connected to that supply.
Specific problems:
Dead- D1 in backwards? 3.5 and 5.0 volt outputs from regulators okay?
Measure supply voltages at a place other than the output pin on the regulator it's self.
Power supply okay, no side tone on power up
Check solder connections on audio amp, U3 and surrounding part, headphone connector, side tone filter, R12, C51 and mute
switch, U4. X6 connections, U6 connections, L7 etc.
Side tone okay, no audio during LO offset trim cal.
Check connections around mixers U1, U2 and mute switch, U4.
Check for DDS output
No DDS output
Check U7 for shorts between pins or pins not soldered to pads on board.
Check connections on all parts around DDS chip
Check for small DC bias voltage across R16. If there, set up data is getting to DDS chip.
Check connections on 60 MHz reference oscillator. NOTE: This is often the cause of no DDS output!
Little or no audio with antenna connected, okay during LO trim cal
Could be anywhere between antenna input and output of U1.
No transmit power out:
Check connections on keying transistors Q4, Q6 and associated parts. D4 maybe in backwards. Check solder connections
on U8. Check connections on C48.
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