In the last few years I have become convinced that the two-tone 3rd order
dynamic range numbers in ARRL reviews measured with a 20 kHz tone spacing
are absolutely irrelevant in demanding amateur radio conditions. The two
tones have to be much closer together in order to get a better idea of what
the receiver will tolerate. I'm glad to see that the ARRL is apparently
getting the message, as I heard recently they were going to start measuring
it with something like a 5 kHz spacing. We should publish the 5 kHz specs
for each of the receivers in Steve's chart.
I define 'demanding conditions' as similar to those in a contest where there
are lots of very strong signals very close to the frequency your receiver is
tuned to.
I'm going to assume that the rest of the DR specs were all measured with the
same receiver bandwidth, although Steve's chart does not explicitly state
this. If not, the numbers don't mean anything to me.
Every one of the receivers listed has way more than enough sensitivity for
any of the HF bands. Since about 1980, MDS numbers have been rendered
irrelevant.
An important spec missing from the chart is that of local oscillator phase
noise, which is difficult to measure and even more difficult to explain
exactly what it does to the way a receiver sounds. In general, the more
phase noise, the more problems that poses to a receiver. One of the
by-products of phase noise is reciprocal mixing. You can definitely hear it,
but describing what it sounds like is hard. That's why during the recent
thread about which receiver was 'quieter' I kept telling myself one of the
parameters going into such a qualitative spec has to be the effects of a
receiving system's phase noise; hence the difficulty in quantifying the
receiver's 'quietness'.
> -----Original Message-----
> From: Steve Ellington [mailto:n4lq@iglou.com]
> Sent: Saturday, 06 April 2002 8:40 AM
> To: tentec@contesting.com
> Subject: [TenTec] Rig Chart
>
>
> I took some data from the ARRL test for these high end rigs.
> Take a peek at:
> http://members.iglou.com/n4lq/img/rigs.htm
> Make of it what you ever you will.
> Steve Ellington N4LQ.
>
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