[CQ-Contest] Fwd: [FCG] riding the RF gain...
tony_brock-fisher at hsgmed.com
Fri Dec 14 09:31:01 EST 2001
>Subject: Re: [CQ-Contest] Fwd: [FCG] riding the RF gain...
>On 12/7/01 8:51 AM, owner-cq-contest at contesting.com at
>owner-cq-contest at contesting.com wrote:
>>driven the technology of receivers forward with our demands for better
>>contest receiver performance, but there is lots of room for improvement
Are You Sure? Do you think we need 110db 3rd order IMD numbers and 170dB
Blocking dynamic range?
Numbers like 95 dB IMD3 and 130 dB BDR are acceptable (and common) today
because there really isn't a need for more.
I'd challenge anyone using a recent rig to claim they couldn't make a QSO
because of intermod or desense, in a reasonable RF environment (using stubs
and common sense as we know it). The atmospheric noise on the HF bands is so
much higher than the noise level of modern receivers that most receivers
should be optimally operated with some attenuation cranked in, at least on
lower HF bands. This extends the already excellent overload characteristics
of recent rigs.
I think we've all gotten hung up on numbers, because they're easy to
compare. But they have limited usefulness, because they represent an
artificial test scenario (two S9+40 signals 20 kHz apart), rather than a
realistic case (a band full of S9 to s9+20 signals spaced every 500 Hz).
>But, isn't it ironic that the Elecraft K2 has better receiver
>characteristics than any of the mult-kilobuck rigs?
Not really! Yes the K2 is a simple, elegant design with really good
performance numbers. BUT, it's not a contest rig, as it lacks many features
now considered essential for serious contest operation. Look at the many
multi-multi's that now run one or two 781's at each position. A major reason
for this is the spectrum scope feature, which helps them find and maintain a
clear frequency. I'm sure we'd all agree that a clear frequency on receive
is worth many dB on transmit... This is just one example - there are many
others, such as power output, all band capability, selectivity options, etc.
Let me know when KC1XX has a K2 at each operating position...
Receiver design is a complex balance of tradeoffs and compromises. The K2
can do an excellent job of receiver performance, because many of the
constraints of a full-featured rig were removed, making it easier to
concentrate on doing 'a few things well'.
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