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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