[Elecraft] Observation on new Synthesizers for K3

[Walter Underwood]

It would help a lot when your neighbor is not transmitting or transmitting on a different band. Plus, it is courteous to transmit a cleaner signal.

wunder
K6WRU
CM87wj
http://observer.wunderwood.org/ (my blog)

On Jul 8, 2015, at 9:04 AM, Alan <n1al at sonic.net> wrote:

> 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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