At 09:06 AM 1/29/2006, Jerry Harley wrote:
Jim Lux wrote:
At 07:25 AM 1/29/2006, Jerry Harley wrote:
I know this has been beaten to death but I never saw anyone say what
they are experiencing.
I had a big problem in the beginning it was off by 278kc, after the
component change I'm off 200 and drift up to dead on in less than 15
minutes. From the 15 minute mark on I see no drifting.
Jerry Wa2tti
you're a quarter of a Megahertz off? Out of what frequency?
Actually, no matter what, that's a huge error. I'd say you have a bad
oscillator.
NO, 200hz off from a cold start and within 15 minutes right on.
Ohhh.. I was going from "was off by 278kc"
So you're looking at 200 Hz out of, say, 14 MHz? That's 10-20 ppm, which
is within spec for the oscillator, I think. It's not a TCXO on the SDR1000
(TCXOs have better frequency accuracy over temperature, but poorer phase
noise, and Gerald picked for performance after warmup). If you're stable
after 15 minutes, then you're in great shape. If you need "turn on and be
accurate within ppm within seconds", you need some sort of other external
oscillator.
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
