Would not K3S' be the plural of K3S? Bob, K4TAX
Sent from my iPhone On Jun 27, 2018, at 4:44 PM, Ian White <gm3...@ifwtech.co.uk> 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: elecraft-boun...@mailman.qth.net [mailto:elecraft- >> boun...@mailman.qth.net] On Behalf Of Don Wilhelm >> Sent: 27 June 2018 14:23 >> To: hawley, charles j jr; Charlie T >> Cc: elecraft@mailman.qth.net >> 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? >>> > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to rmcg...@blomand.net > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
