[time-nuts] DDS module

[Nic McLean]

Hi Joe,
It is good that they are that stable, but what is the phase noise like? If a
ham across town is using them for WSPR and QRSS they are most probably OK in
that regard, but not all DDS modules are.
Best 73's
Nic
VK2KXN / VK5ZAT

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Joseph Gray
Sent: Sunday, 21 July 2013 2:04 PM
To: Discussion of precise time and frequency measurement
Subject: [time-nuts] DDS module

I have a few of those $5 AD9850 DDS modules from China. I'm going to use one
to replace a crystal in a transmitter. I attached it to a TI MSP430
Launchpad and programmed a fixed frequency.

Just out of curiosity, I wanted to see how stable this thing is. Using
cellophane tape, I put a few pieces of foam around the oscillator can. Then
I hooked it up to my HP counter, which is locked to my GPSDO.

I'm not logging, but I have kept an eye on the setup for well over 24 hours
now. So far, the frequency has held to within 0.01-0.08 of the programmed
value.

The house thermostat is set at 75 F, but this room gets somewhat warmer due
to the equipment in it. Also, this room gets the morning sun.

Considering the cost, I am impressed with how well this little module works
and how stable it is. There is an Amateur in town who has been using several
of these modules to drive WSPR and QRSS transmitters. He has done up a poor
man's oven to keep his transmitters on frequency.

Joe Gray
W5JG
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