http://elecraft.85.s1.nabble.com/K3-factory-upgrade-to-K3-s-tp7642388p7642464.html
... or not.
> Would not K3S' be the plural of K3S?
>
> Bob, K4TAX
>
>
> Sent from my iPhone
>
> On Jun 27, 2018, at 4:44 PM, Ian White <
[hidden email]> wrote:
>
>>> A big reduction in receiver noise floor and a huge improvement in
>> both
>>> transmit and receive phase noise.
>> That is far too simplistic. Anyone's personal definition of "the
>> better synthesizer" will depend on what range of frequency offsets
>> is more important for their particular type of operating.
>>
>> For HF CW in particular, phase noise at small frequency offsets is
>> of paramount importance and I wouldn't argue with Don's report of "a
>> huge improvement in both transmit and receive phase noise" - but
>> *only* in that specific context. There are also several other
>> advantages that are relevant to high-performance HF CW that could
>> also justify upgrading to the KSYN3A.
>>
>> At close frequency offsets from the carrier, the KSYN3A does indeed
>> offer a large reduction in phase noise compared with the KSYN3
>> (which itself was already good). But at wider frequency offsets,
>> that situation reverses. According to the ARRL review [1], at all
>> offsets beyond about 6kHz, the older KSYN3 continues to have a lower
>> noise floor than the newer KSYN3A "upgrade".
>>
>> Performance at wider frequency offsets, 10-100kHz and beyond, is of
>> much greater importance in VHF-UHF contesting. This due to a
>> combination of factors. The strongest signals at VHF-UHF are often
>> much stronger than on HF, due to the use of high-gain beam antennas;
>> and also the weakest signals are *always* much, much weaker due to
>> the lower levels of natural background noise. These two features
>> stretch the requirement for dynamic range on VHF-UHF far beyond
>> those for which most HF transceivers are designed.
>>
>> Anyone transmitting wideband phase noise has a much greater risk of
>> raising the noise floor of many other stations across the whole
>> contesting segment of the VHF or UHF band. Running the numbers
>> reveals that anyone aiming to be a Big Gun in VHF contests has a
>> responsibility to keep their wideband transmitted noise floor below
>> about -130dBc/Hz at frequency offsets of 50kHz and more [2]. This
>> can be a major engineering challenge, and the performance of the
>> transceiver is almost always the most important building block.
>>
>> The KSYN3A just about meets the -130dBc/Hz noise floor target at
>> frequency offsets of 10kHz or more... but according to the ARRL
>> review [1] the older KSYN3 achieves it much more comfortably, with
>> 10-15dB to spare.
>>
>> I have both a K3S and a very early-model K3. The K3S (with the
>> KSYN3A, of course) is used for HF contesting where smaller frequency
>> offsets are important. Meanwhile the old K3 is now used as a
>> transverter driver for 144MHz and above - and for that particular
>> purpose there are very good reasons *not* to replace the original
>> KSYN3.
>>
>> 73 from Ian GM3SEK
>>
>>
>> [1]
>>
http://www.arrl.org/files/file/ProductReviewsForDeb/2015/pr112015.pd>> f
>>
>> [2]
>>
https://thersgb.org/members/publications/video_archive.php?id=5703>> Sorry, this talk is accessible only to RSGB members, but in a few
>> words...
>>
>> G8DOH runs the numbers to demonstrate that the -130dBc/Hz target
>> for transmitted phase noise is necessary to avoid raising the noise
>> floor of other stations many kilometres away, and also many tens to
>> hundreds of kHz away across the band, whenever their high-gain beams
>> happen to be pointed at each other.
>>
>> That calculation assumes the UK transmitter power limit of 400W PEP
>> output. For the US power limit of 1500W output, keeping all other
>> assumptions the same, the target for transmitted noise floor would
>> need to be better than -135dBc/Hz. The older KSYN3 can still meet
>> that more stringent target but the KSYN3A probably cannot.
>>
>>
>>> -----Original Message-----
>>> From:
[hidden email] [mailto:elecraft-
>>>
[hidden email]] On Behalf Of Don Wilhelm
>>> Sent: 27 June 2018 14:23
>>> To: hawley, charles j jr; Charlie T
>>> Cc:
[hidden email]
>>> Subject: Re: [Elecraft] [K3] factory upgrade to K3(s)
>>>
>>> Chuck,
>>>
>>> A big reduction in receiver noise floor and a huge improvement in
>> both
>>> transmit and receive phase noise. It is like getting a new
>> transceiver.
>>> If you are strictly a casual operator, those qualities may not be
>>> important to you, but if you are a DX'er or a contester, or
>> otherwise
>>> operate in crowded band condition, those things should be important
>>> to you.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>>> On 6/27/2018 9:03 AM, hawley, charles j jr wrote:
>>>> I decided to bypass the replacement of the synthesizers. Could
>> you
>>> describe the "huge" difference?
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