[Elecraft] Synthesizer Issue

[David Anderson]

Wayne,

For folks that were using the two receivers for VHF EME polarity diversity reception over a wide bandwidth with MAP65 software, where they would have gain and phase matched preamps this must be an improvement for them. 

I think it was not generally understood that the absolute value of the phase relationship of the receivers would change as the VFO was moved. The only person I know that is currently using his K3 for doing this is Ed KL7UW, so he may be interested in this.

73

David Anderson GM4JJJ 

> On 3 Mar 2015, at 02:21, Wayne Burdick <n6kr at elecraft.com> 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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