"Ian Jackson" wrote in message
...
Which is greater - 10db or -30db?

In voltage ratios, they are 1/3 and 1/30 respectively, and in power
ratios, 1/10 and 1/000 respectively. But if you lost 30dB down your coax,
you'd be losing 20dB MORE than if you were only losing 10dB. But surely
even you wouldn't say "My coax has a loss of minus 30dB"? [Or would you?!]

dB without a refferance to something like voltage or power is not much if
any use.