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Re: [CQ-Contest] TX phase noise - comparing Apples to Apples?

To: William Hein <bill.aa7xt@gmail.com>
Subject: Re: [CQ-Contest] TX phase noise - comparing Apples to Apples?
From: Brian Hemmis <bhemmis@mac.com>
Date: Thu, 30 May 2013 18:27:58 -0400
List-post: <cq-contest@contesting.com">mailto:cq-contest@contesting.com>
I believe Paul, W9AC, has an ADAT-200A...and a K-3
73, Brian K3USC


On May 30, 2013, at 12:07 PM, William Hein <bill.aa7xt@gmail.com> wrote:

> I am collecting info on tx phase noise on current rigs and am not sure I am 
> interpreting the data correctly.  I am also collecting techniques to mitigate 
> same.  
> 
> The Swiss company that makes the ADAT-200A advertises ", the transmit signal 
> is processed by adaptive predistortion, a technique that is used for the 
> first time in amateur radio. This technology stands out due to high 
> efficiency and a remarkably clean transmit spectrum, combined with an 
> exceptionally clear modulation."   But does anyone actually have a ADAT-200A?
> 
> Will GPS clock syncing the LO reduce tx phase noise?
> 
> Will operating a tx in Class A reduce tx phase noise?  I believe the 
> FTdx5000MP will operate in Class A, not sure about other rigs.  (Not sure 
> Class A applies to CW mode operation.)
> 
> Seems like a good idea to leave ALC switched off, true?
> 
> The Flex 6000 series, according to a recent newsletter:
> "the preliminary specifications provided in the FLEX-6000 Signature Series 
> brochure projected an industry leading phase noise of -147 dBc/Hz at a 10 kHz 
> offset and -152 dBc/Hz at a 100 kHz offset. After detailed phase noise 
> measurements in the lab, lets just say we have a great big smile on our face!"
> 
> By way of comparison, here is some info on the K3 vs. other rigs reported by 
> Elecraft's WA6HHQ which I found via Google:
> 
> "Here are transmit composite phase noise numbers from the Lab for the K3.
> Needless to say, we are pleased with the results. :-) I've also included
> some numbers from the ARRL reviews for several late model rigs.
> 
> Rig     1kHz    2   10   20   50   100   1M
> K3      -110  -119 -136 -140 -143 -144  -150
> IC7800  -103  -112 -130 -138 -140 -140  -140
> FT2000  -102  -105 -128 -129 -128 -128  -128
> ORION 2 -121  -129 -126 -125 -118 -128  -138
> OMNI 7  -102  -103 -120 -123 -127 -129  -126"
> 
> How to compare apples to apples here?  How does -147 dBc/Hz at 10 kHz offset 
> measure up with the -136 dB @ 10 kHz figure reported for K3 above?  Even 
> thought "dB" appears in both measurements not sure they are using the same 
> reference point or are indeed the same metric at all.
> 
> 73
> Bill
> 
> William Hein, AA7XT
> ex-AA4XT, NT1Y, AA6TT, KC6EDP
> 
> Blog   AA7XT.com
> 
> ARRL, CSVHF & AMSAT Life Member
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> 1st licensed 1969 - WN6NDC
> 
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> 
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> 
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