[Elecraft] Synthesizer Issue

[Brendan Minish]

Wayne,

This IS a big improvement for us Diversity users, particularly when
using diversity to keep track of a pile of callers in a contest pileup.

With the Old synths since the phase relationship between the 2 vfos
would shift after TX the positioning of callers in the Image would alter
after each transmit operation, with the new Synths this no longer
happens.

The already very good Diversity mode has gotten much better with this
upgrade. I'd also suggest that folks who didn't take to diversity before
might wish to give it a second try.
For Diversity reception the RX antenna needs to be different than the TX
antenna (E.g a vertical and a beam, or a doublet )  you don't need a
dedicated RX antenna, it just needs to have different characteristics
than the main antenna. Physical separation &/or polarity differences
will also help.

For me, the price of the upgrade was worth it for the Diversity
improvements alone    


73
Brendan EI6IZ

On Mon, 2015-03-02 at 18:21 -0800, Wayne Burdick wrote:
> Some users of the new synthesizer have also reported an improvement in the way diversity mode sounds. This is due to a change in the way the receivers are driven by the synths. 
> 
> In diversity mode, as long as the main and sub crystal filter offsets are matched, both receivers are driven by the main synth (the sub synth is not used in this case). So, when the VFO is moved, the local oscillator phase relationship remains stable between the main and sub receivers. 
> 
> With the original synths, moving the VFO even a small amount causes both the main and sub synths to be updated. Since they use separate LC oscillators, the phase relationship will change. The two will remain phase-locked to the reference, but the absolute value of the phase between the two synths will be some value between 0 and 180 degrees.
> 
> We'll add this to the FAQ.
> 
> 73,
> Wayne
> N6KR
>  
> 
> 
> On Mar 2, 2015, at 6:10 PM, Walter Underwood <wunder at wunderwood.org> wrote:
> 
> > Start with the FAQ here: http://www.elecraft.com/manual/KSYN3A%20FAQ-ver-C-2.pdf
> > 
> > The original announcement on this list described it like this:
> > 
> > The KSYN3A synthesizer module is a completely new design that improves on the original KSYN3 in several ways:
> > 
> > ULTRA-LOW PHASE NOISE
> > The KSYN3A significantly improves the K3's already excellent RX and TX phase noise at close carrier spacings. This in turn noticeably improves the K3's top performing close spaced Rx dynamic range, yielding even better weak signal detection in the presence of strong signals.
> > 
> > FASTER CW BREAK-IN AND MORE ACCURATE CW ELEMENT TIMING
> > 
> > EXCELLENT MECHANICAL STABILITY
> > The KSYN3A is virtually immune to both physical vibration and magnetic coupling, and operates over a very wide temperature range.
> > 
> > 600-METER COVERAGE
> > The KSYN3A extends VFO tuning down to 100 kHz, with sensitivity gradually falling off below 450 kHz. Transmit output is as high as 1.0 mW for use with a suitable external amplifier. (Note: 600-m and below operation also requires the KBPF3 and KXV3 options.)
> > 
> > wunder
> > K6WRU
> > CM87wj
> > http://observer.wunderwood.org/
> > 
> > On Mar 2, 2015, at 6:02 PM, James D. (Jimmy) Walker, Jr. via Elecraft <elecraft at mailman.qth.net> wrote:
> > 
> >> Can someone please give me a summary of this synthesizer issue or a useful link so I can understand all this conversation about new boards. I have a three year old K-3 and a one year old sub-receiver. Do I need these boards? What would they do for me? An off-list reply is welcome since it appears I’m the only one who doesn’t know what’s going on. Thanks.
> >> 
> >> Jimmy, WA4ILO
> >> 
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-- 
73
Brendan EI6IZ