[TenTec] Effect of roofing filter selection on Orion II NB

[Grant Youngman]

>          Did you mean to write NB instead of "NR" above?

Yes, and I checked it 10 times, because that's an easy mistake to make.  Oh,
well :-)
 
>          Simply not possible.  10 dB improvement at 100 Hz 
> implies a noise bandwidth of 10 Hz, which is far too narrow 
> even to copy 15 WPM CW.  

Perhaps "on the order of something greater than zero" would have been a more
correct statement.  In any case, there is additional improvement.  It is
clearly audible, and there is a clear difference between the signal+noise
output to noise-only output with NR on versus NR off.

So I remeasured it, just a minute ago.  Very simple.  Used a TS-585D/U Audio
output meter on the radio's output (one channel to monitor, one channel for
the meter.  (1) With NR off set the baseline noise level to read 0dB on the
meter.  (2) Tuned to signal, read output level in dB.  (3) Turn on NR
(signal level will drop) and adjust audio output to restore the signal level
reading in (2).  (4) Read background noise.  

Reads almost exactly -10dB (that's dBm, by the way).  I did it on a steady
carrier this time, to minimize the "eyeball error" in the meter reading.
Maybe I'm misinterpreting?

Grant/NQ5T