Hi Ken The problem might be if you are deriving the frequency direct from R4
via a PLL you will have severe problems if/when the PLL unlocks due to noise
or fading. The best bet is to run a loop on SpectrumLab and watch the drift
rate .....OK you will actually be seeing the soundcard drift but you will
notice if the PLL becomes unlocked. I find that I get periods on a Halcyon
off-air standard where the noise spoils the lock and the output thrashes
around. You may get a more reliable signal than I do. I use a good ovened
crystal which is manually adjusted to R4 frequency.

Alan G3NYK

----- Original Message ----- 
From: "Ken" <[email protected]>
To: <[email protected]>
Sent: Friday, March 18, 2011 7:54 PM
Subject: LF: Frequency Stability


To All VLF.
Is the following frequency stability sufficient for Spectrum Lab:

1MHz and 10MHz derived from Radio 4 198 kHz  Accuracy 2 parts in10-8 over 1
sec,2 parts in10-9 over 10secs.


73s

Ken

M0KHW  IO91TV