Topband: Omni VII performance on 160m

Svein Nordhuus Moe sveinmoe at
Sat Jun 30 15:01:57 EDT 2007

Hello Petr.

I tend to agree with you.
The proposed concept of "Distributed Roofing Filter Architecture" seems 
rather strange.
To me this seems to be an oridinary general coverage radio design with 
20KHz roofing filter and some ordinary filtering further down the signal 
Since its made by TT it is likely to be better designed than many of the 
Japanese machines, and that seems to show up in the measurements as well.
Seems they have adjusted the total signal chain to give the best 
possible result within the inherent limitations of a wideband-input radio.

The FANTASTIC feature of this radio though is the Ethernet remote control.
This feature alone plus the CW break-in features would be enough to have 
the radio for general use if not for extreme160m DX-ing.

BTW. I have both the K2, and the now rather old TT OMNI-D from the 1980's.
An acid test for CW DX radios in my view is the CQWW on CW. The 
broadband (out-of-filter-bandwidth) signal-pressure on the radio is 
tremendous at peak CQWW hours. Although the K2 is one of the best radios 
around today, those are the few days when you will experience filter 
blow-by in the K2. There are birds singing at a constant level in the 
background wherever you tune along the bands. You will feel some of the 
same broadband noise pressure in your headphones on a noisy winters day 
on 160. The old OMNI-D on the other hand  just delivers the stations 
clearly both on CQWW and on other days on 160. And the 2nd hand price is 
only 300 USD or less. It does have its own small flaws, like the AGC 
handling of extremely large signals within the filter band, but on 
average this is my 160 favourite. Seems that they started out by 
optimizing the radio for 20m and then reduced the sensitivity for each 
band down to 160. This matches the the noise level that you are likely 
to experience on the bands quite well, and it may save your ears.

73 de Svein, LA1SJA.

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