I hope someone can explain the roofing filter operation in the Orion.
Either I don't understand something, or I may have a defective 250 Hz
filter.
I have added all three optional roofing filters from to my Orion. These are
stock TenTec supplied filters that had been used in my Omni VI.( opt 3 )
(only two at a time, though <g>).
My thinking is that with the roofing filter manually selected and the DSP BW
opened all the way up, the audio response of the Orion would be controlled
primarily by the roofing filter.
For a test, I supplied a broadband RF signal (used my MFJ MatchMaker for
Tuner with no antenna) to the Orion. I monitored the audio using the
spectrum display of MixW running on my computer. The display was configured
to show the instantaneous and average signal. I set the Orion to CW receive
and set the DSP bandwidth to 6 kHz.
I then used the roofing filter menu to force selection of the individual
filters. With the 500 Hz, 1 kHz, 1.8 kHz, 2.4 kHz filters the spectrum
display shows a 10 - 15 dB peak in the audio response corresponding with the
passband of the roofing filter. With the 6.0 kHz filter, I also see a peak
although it is only about 4 kHz wide. With the 20 kHz filter there is no
peak, but my spectrum is only 5.5 kHz wide so that isn't unexpected.
However, with the 250 Hz, there is no peak, the spectrum looks and sounds
almost identical to the spectrum with the 20 kHz filter selected. I tried
adjusting the 250 Hz filter centering over the entire +/- 250 Hz range and
saw no change in the spectrum.
With on the air testing, I am able to receive signals with the 250 Hz filter
selected, so the Orion does act as if a filter is installed.
Any suggestions?
73,
Mark
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|