Jim, thanks for taking the time to do that.
This is good information.
There is still one more piece missing, far out Phase Noise and my hunch is
you would find a larger difference.
This graph shows the in-band phase noise.
What's it like when you are 10 MHz away but with an antenna in near
proximity of the radio under test?
I asked Rob and he stated that he had never measured this.
I don't think the ARRL has either.
It is my understanding that the real difference is when you are farther away
from the transmitted frequency.
Thanks for sharing this with us, Jim!
Good luck in the IOTA contest.
73 - Rick, DJ0IP
(Nr. Frankfurt am Main)
-----Original Message-----
From: TenTec [mailto:tentec-bounces@contesting.com] On Behalf Of Jim Brown
Sent: Sunday, July 27, 2014 7:32 AM
To: tentec@contesting.com
Subject: Re: [TenTec] Rigs at WRTC
In between slow periods in IOTA today, (and there are a LOT when you're on
the west coast) I did this. Here's the graph. The closer the curve is to
the bottom of the graph, the cleaner the radio.
k9yc.com/TXPhaseNoise-1.png
As was noted. these plots is the noise in a 1 Hz bandwidth. Most of us
listen to CW with 400 Hz filters, and SSB with about 2.8 kHz, so we'll hear
the sum of all those 1 Hz pieces. This is only the contribution of phase
noise to what you hear off frequency. There's also distortion, both at audio
and RF, and clicks.
Rick's team are definitely not wrong in their assessment of the TS590.
The best you can say about it is that it's not quite as bad as the
IC7600 that my neighbor uses to drive a legal limit amp. He's also a retired
NY lawyer, with attitude to match.
73, Jim K9YC
On 7/26/2014 3:21 PM, Jim Brown wrote:
>
> To compare the radios, you've got to pick values off each graph and
> plot them on the same graph. These graphs are printed to different
> scales and the scales are more scrunched than they should be, so it
> takes practice to get within a dB or two.
>
> These are plots of phase noise (see the test procedures manual). The
> measurement bandwidth for the dB value shown is not specified. Phase
> noise is the whooshing sound you hear when another TX is keyed. You
> hear your own phase noise as well as that of your neighbors.
>
> Note that phase noise performance is different on RX and TX, depending
> on the design of the rig. Thanks to Rob Sherwood's RX testing, mfrs
> have been working on improving their performance. But because
> relatively little attention has been paid to TX trash, that hasn't
> happened.
>
> 73, Jim K9YC
>
>
>
>
>
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