Re: LF: Re: DK7FC's 7th VLF kite experiment

[Jacek Lipkowski <sq5bpf@lipkowski.org>]

On Sat, 2 Oct 2010, James Moritz wrote:

> [...] I think this is due to the cooling fan in the laptop cycling on 
> and off every minute or two, frequency modulating the soundcard clock by 
> several millihertz due to the changing temperature. I think if this 
> instability could be eliminated, the SNR would be improved by some dBs. 
> [...]
in one of my laptops (lattitude d610) i just turn on the fan via acpi. in 
the other laptop (lattitude e4300) it just runs continiously when i 
run Spectrum Lab anyway. this is under linux, but there is 
probably some software to control the fan under windows too. it is also 
good to change the max sleep state that the devices will go into - turning 
off powersaving features cuts the sound card spurs very well.
it is also good to turn on the laptop one hour before transmission, so 
that it reaches thermal stability
VY 73

Jacek / SQ5BPF