I don't know where Rob got the O2, but the K3 was not a factory-picked unit.
It was built by and belongs to Mike, K6AER who loaned it to him about two
weeks ago for the test. In all fairness, Mike is a professional
communications engineer and has access to lab-grade equipment, so if there
was anything amiss on his unit, he would have had the factory fix it before
it went to Rob.
I agree....a 200 Hz filter would be great for the O2! I also suspect that a
different master oscillator (more stable, please!) with lower noise might
improve the measured specs, although it may be the rest of the synthesizer
circuitry that limits the result. Check this unit:
http://www.wenzel.com/pdffiles1/Oscillators/sprinter_30_to_130.pdf
All that being said, we have probably reached a point where the practical
value of greater close-in rejection is limited by transmitted key clicks and
SSB splatter.
Ron N6IE
www.N6IE.com
----- Original Message -----
From: "Dennis OConnor" <ad4hk2004@yahoo.com>
To: <tentec@contesting.com>
Sent: Monday, February 18, 2008 9:42 AM
Subject: [TenTec] O2_dreps_top_spot
> Well, a tip of the hat to Elecraft, they have raised the bar... I will
> might just have to have one of these...
> Along the way to admiring their test results I noted a couple things - in
> no particular order...
>
> Looks like the K3 synthesizer is quieter than the OII which is phase
> noise limited on the narrow test... Ten Tec needs to boogity, boogity
> (racing slang)
>
> If I read Rob's comments correctly in the white papers section the K3 was
> a repeat test on a hand picked and factory optimized sample... I am not
> aware of how the OII came to Rob's hands...
>
> The K3 narrow test was done with a 200 cycle, 5 pole crystal filter...
> The narrowest OII factory filter I am aware of is 300 cycles and (?) 4
> poles <too lazy to look it up>... I suspect that this killer filter is a
> big part of those extra dB's (hint hint, TT)
>
> If you read Rob's white papers carefully he states that no contestor
> contests with the AGC off and riding the RF gain by hand, so he tests the
> radios with the AGC on, which degrades ultimate performance... Well,
> surprise, surprise, this contestor always runs with the AGC off and riding
> the gain control... So, he needs to revisit this (which will likely
> benefit both radios)
>
> Anyway, those were my random thoughts on looking over Rob's receiver test
> data... I wonder who was there to optimize the OII during testing as this
> is a radio that needs an experienced hand to get the most out of it...
>
>
>
>
> denny / k8do
>
> ---------------------------------
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