Jim,
I agree, this was really a very strange failure in our case. We found out
that the circuit did not function with our test program if the "sinc" and
"multiply" options were included. When we removed those functions from the
control program, both I and Q signal were present. We also noticed that the
total current consumption was considerably lower. Unfortunately I did not
make any notes, but if I remember it correctly it was slightly above 500 mA.
After a lot of measurements, optical inspections, mechanical stressing
(twisting, shocking, vibration) I am pretty much convinced that it was the
failure of AD9854. Unfortunately I have no possibilities of etching the
package open for microscopic inspection of the bare die.
73, Ahti OH2RZ
----- Original Message -----
From: "Jim Lux" <[EMAIL PROTECTED]>
To: "Ahti Aintila" <[EMAIL PROTECTED]>; <[EMAIL PROTECTED]>;
<FlexRadio@flex-radio.biz>
Sent: Saturday, October 01, 2005 5:07 PM
Subject: Re: [Flexradio] Receiver dies 2 min after power-up, ideas?
At 06:09 AM 10/1/2005, Ahti Aintila wrote:
I can confirm Eric's statement. One of our three SDR-1000 systems had this
problem. Cooling down the AD9854 helped temporarily. Then I installed a
bigger heatsink that worked a couple of weeks until the synthesizer got
damaged so badly that it did not work any more with any version of the
PowerSDR software. Amazingly though, with one of our own small test
program
it still worked. However, for fully functional tasks of the PowerSDR the
chip had to be replaced.
Thermal damage that results in a partial failure? This brings up an
interesting question. Is there some sort of simple diagnostic program or
process that could be used to determine if this has occurred?
Did you do any sort of failure analysis on the part that was removed?
73,
Ahti OH2RZ
James Lux, P.E.
Spacecraft Radio Frequency Subsystems Group
Flight Communications Systems Section
Jet Propulsion Laboratory, Mail Stop 161-213
4800 Oak Grove Drive
Pasadena CA 91109
tel: (818)354-2075
fax: (818)393-6875
