[Elecraft] Observation on new Synthesizers for K3

[Alan]

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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