[Lf] DDS board availability

[Larry Kayser]

Finally, maybe a DDS board available soon.

Andy, G4JNT is considering producing a PC board that has a PIC controller IC
controlling one of the Analog Devices AD9850 chips.  This gives one a DDS of
the highest quality.  The Reference oscillator can be anything available,
from atomic standards to simple reasonable quality oscillator modules up to
100 MHz or so.  The OUTPUT from the DDS is up to 1/2 of the reference
frequency, a 5 MHz oscillator will allow steps as small as a few milliHz
from a few kHz to 2500 kHz.  These devices are excellent for making LF
transmitters that can easily do FSK, PSK etc.  They can also be used as
Local Oscillators and BFO's for a super stable receiver as well.  If you
might be interested read Andy's email that follows and you can email to Andy
at

Talbot Andrew <ACTALBOT at dera.gov.uk>

and let him know.  PLEASE REMEMBER EMAIL ANDY AND NOT ME HI.........

I am considering bulk manufacture of a Printed Circuit Board for the
AD9850 DDS chip.  The design has already been tested and includes the
DDS, output filter, voltage regulator and a 16F84 PIC.  Resident
software allows the DDS source to be controlled over an RS232 link from
a PC with ASCII commands.  This allows for control from a simple
terminal programme as well as custom software for PSK/ FSK etc.   There
is no reason why different PIC software can't be used for keyboard /
rotary encoder etc.   Mostly surface mount (large 1206 components
though)  but conventional PIC in a socket for easy firmware changes.

If there is enough interest I will go ahead with a PCB order.  It is
possible a company (see   WWW.HF-INST.CO.UK  ) may take the design on
board and market as a complete signal source, but for now I will just
get PCBs made if enough interest is shown.  Not sure of the price, it
depends on such things as quantity, how many plated through holes,
delivery timescales and probably the phase of the Moon !

The DDS can be clocked with any frequency source desired.   For LF I use
a 5MHz input derived from a master reference which allows outputs up to
1.7 MHz with 0.001 Hz resolution, but any clock up to 120MHz (40 MHz
maximum output) is useable.

Anyone interested, please let me know so I can get an idea of whether it
is worth going ahead with a commercial run.

Andy  G4JNT