[TenTec] O2_dreps_top_spot

Mark pa5mw at home.nl
Sun Feb 24 07:11:44 EST 2008


Barry N1EU wrote:
>   The reason it doesn't ring at
> 100hz is because the filter slopes are fairly shallow compared with
> other radios, even with the Orion filtering set to 199 Taps.  To some
> extent, the filter is really broader than indicated because of the
> shallow slopes.  
>
>   

OK, thanks for explaining that !

Yesterday I did spend another hour on the K3 after its firmware and DSP 
software had been updated to the latest versions.
Several weeks ago I noted that the K3:
- has more or less an audio "peaking" filtering behavior on 50-100-150- 
200 Hz  DSP filter setting
- audio peaking behavior does make extreme weak signals stand out when 
on a dead band, like when connected to the X144 transverter plus antenna
- same effect suffers from ringing effects at HF, especially on the low 
bands

Yesterday I listened again carefully; at 200Hz is was better, but from 
150Hz and below it remains the same.
Tuning the 160m band at 100Hz is not possible and unpleasant for my 
ears. You hear a hollow sound and each key-clicks from distant other 
loud stations appear with heavy ringing effects.
This is the biggest difference with my Orion, where I can tune the 160m 
band at a BW of 100Hz which sounds just as relaxed as it does at 400Hz.

For the sake of the test I repeated my observations disabeling the 
internal 200Hz 5pole roofing filter and using the 400Hz- 8pole roofing 
filter onlyon the K3.
The same effects below 200Hz DSP filter setting were noticed. So the 
type of roofing filter does not seem to be the cause here.

To be honest, since Barry explained the difference in DSP algorithm 
between the Orion and K3, 100Hz at the Orion is not the same as 100Hz on 
the K3.
Again a bit apples&oranges here.

'73 Mark, PA5MW

http://pa5mw.blogspot.com






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