While in full and total agreement, I do admire and highly respect and more
so do appreciate the efforts of Rob Sherwood. His data on receivers is
basically "unchallenged" in today's receiver performance market. At the
same time, I would point out that there are other significant factors
relating to receiver performance other than the 2 KHz dynamic range. He
presents this information based on this single factor. I suggest one
download the data to an Excel Spreadsheet thus allowing one to sort on
different parameters. It's enlightening to say the least.
I do recall a comment and I hope I paraphrase Rob correctly; a dynamic range
of 80 dB or greater is likely not to be noticed by most hams in most
applications and operating instances. Only the most intense contest
operation with multiple stations on the air simultaneously would likely
benefit noticeably from the added performance.
His presentations to the various radio clubs and the Dayton Hamvention are
very informative and equally easy to understand.
73
Bob, K4TAX
----- Original Message -----
From: "GARY HUBER" <glhuber@msn.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Sunday, January 20, 2013 5:00 PM
Subject: Re: [TenTec] Paragon II Failure to Transmit
Rob Sherwood explains in
http://www.sherweng.com/audio/Sherwood_CU_2008_final_b.wmv What dynamic
range is possible and needed for CW? 80 dB or better @ 2 kHz including the
2007 Ten-Tec Omni-VII: 80 dB
Pete, I do not want to offend you, but I suggest you review the Rob
Sherwood presentation. I think you may have missed something regarding the
70 MHz IF 20 kHz filter's role and that of the 500 Hz filter in the 2nd
IF. The graphics and audio by an engineer are much better than any
attempt by me.
73 ES DX,
Gary -- AB9M
-----Original Message-----
From: Peter Bertini
Sent: Saturday, January 19, 2013 6:37 PM
To: TenTec@contesting.com
Subject: Re: [TenTec] Paragon II Failure to Transmit
I may be missing something, but I don't see how the 455kHz mechanical
filters can do much to improve the 2nd mixer in band IMD performance for
the Omni VII. The limiting factor is the 70 MHz 1st IF filter which has a
wide 20 kHz BW. It looks to me the same problem when comparing in close CW
performance between my Omni VI and Paragon II. The Paragon has the same 70
MHz 1st IF problem and lack of early protection for the second mixer.
(Besides the phase noise issues).
Pete k1zjh
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