By the way, a corollary to this is that it doesn't help much to improve
the phase noise of your radio if your neighbor's radio is dirty.
Alan N1AL
On 07/08/2015 08:45 AM, Alan wrote:
On 07/08/2015 06:02 AM, David Cole wrote:
It occurs to me that the the the RX VFO phase noise would be less
influencing, (on phase noise sidebands), than the transmit VFO phase
noise... Is that correct?
If so, then that would explain why the largest change occurred when
K7OLN got his new synthesizer, as opposed to me getting my new
synthesizer, as shown in the difference between photos 2 and 3.
I believe the TX and RX phase noise have an equal effect on the
interference.
Let's say the phase noise of the new synthesizer is 10 dB better than
the old at a particular offset frequency. That is, 1/10 the power.
If you replace one synthesizer (RX or TX) then the total phase noise is
reduced by a factor (1 + 1/10) / (1 + 1) = 0.55 or -2.6 dB.
If you replace both synthesizers, then the total phase noise is reduced
by a factor (1/10 + 1/10) / (1 + 1) = -10 dB.
I don't think it makes any difference which synthesizer is changed first.
Alan N1AL
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