Version: 13. Sepe,mer 2004
14
pin 13 must measure +10 Volts
Pin 39 should be at +10 Volts, when not keyed,
and when keyed, at 0 V
Pin 40 should be at 0 Volts , when not keyed,
and at 10V when keyed.
For a closer look to the function have a look at the logic plan in the sche-
matic part.
Section 3 DDS VFO
The heart of the DDS VFO is the IC AD9835BRU, which is already mounted
on delivery. most other parts are well known. As allways, take care to check
the markings to avoid mixing up parts. It is often impossible to read the
markings on the small ceramic capacitors. This is unfortunately impossible
to change, so they will have to be measured. As most cheap multimeters
today measures capacitors to below 1 pF, this should pose no problem.
(Multimeters are offered by QRPProject at 29 Euro).
[ ]C13 1nF 102 C6
[ ]C14 8p2 8p2 C6
[ ]C15 220pF 221, n22 C6
[ ]C16 68pF 68p C6
[ ]C17 470pF 471, n47 C6/7
[ ]C18 68pF 68p C7/6
[ ]C19 220pF221, n22 C7
[X] C22 100nF SMD 0805 B6
[X] C23 10nF SMD 0805 C6
[X] C24 10nF SMD 0805 C7
[ ]C25 22pF 220,22p B6
[ ]C26 22pF 220,22p B6
[ ]ST3 3 Pin Connector A6
[ ]C27 10nF 103 A6
[ ]C28 10nF 103 A6
[ ]C29 470pF 471, n470 A7
[ ]C30 100nF 104 A7
[ ]C33 10nF 103 C7
[ ]C31 10nF 103 B7
[ ]C32 10nF 103 B7
[X] C34 100nF SMD 0805 B7
Now mount the socket for the processor. Please take care to mount it as
shown in the diagram. The notch on the short side should be mounted as in
the placement diagram.
[ ]IC7 socket 20 PIN A/B7
Take care of statics, the Processor is very sensitice against
Electro Static Discharge (ESD)
To Next Page
Loading...