[Lowfer] Level Settings

[Andy - KU4XR]

After reading Steve - W3EEE's post about RF Gain, and AGC settings; It caused me to think back a few years to when I was playing around with the old Boat Anchor receivers in my A.M. days on 75 meters. I would listen to The Grand Ole Opry on WSM in Nashville with the AGC " OFF " and use the RF Gain control to set the volume to a comfortable level. Using a good full range speaker, the fidelity was superb this way. Local stations sounded great, with their full 10 KHz of audio on music. Then I remembered reading that many CW operators do the same thing to help overcome the impulse noise such as lightning crashes. Soooo, for a few days now, I have been doing this at night on 80/160/600 meters. I can't turn the AGC " OFF " so I have to stick with the " FAST " setting. I really began to pay attention to what I was hearing from the speaker, looking for improvements, and in the short term, it appears that using this method has indeed improved the " quality " of
 the signal being received. What I have noticed is: with the AGC set to " FAST " and the RF Gain at " MAXIMUM " the rapid impulses from the numerous lightning crashes, being almost continuious, caused a severe " fluttering " or I have sometimes heard it called " Motor Boating " sound, even similar to the " Picket Fencing " sound on 2 meters from someone in mobile operation. I hadn't really paid any attention to just how annoying that sound actually is. I began to lower the RF Gain stage until my meter just quit flickering. Other than the occasional static crash breaking through, the background noise all but " went away ".
My first thought, as I had posted previously was that weak signals would not make it through with the RF Gain backed off. I was wrong.... and found this to not be true. The weak signals still came thru, and even seemed to be cleaner on the waterfall display, just as Steve mentioned. And the " hash " that I normally see on the display disappeared. I was copying Pat - WD2XSH/6 the other night on 495.028 KHz in QRSS-10 and CW. The static crashes were terrible, and were destroying his signal.On the Spectran waterfall, his signal looked severly ragged, and sounded the same too. I began to roll off the RF Gain, and as the noise impulses began to drop; I noticed that Pats signal began to clear up. In audio, as well as on the waterfall display. When I set the RF Gain to where the meter stopped flickering, Pat was perfectly audible, with no " fluttering " sound, and his trace on Spectran was a perfect line, with no " jagged " edges. I can't say that I didn't know
 about this, but I can say that I had forgotten about it, and the thread the other day brought it out from the recesses of my mind. By using the RF Gain, I was able to make Pats signal go from an uncomfortable listening experience, to a pleasant to listen to signal. From what little I have tried it on WSPR signals, it appears that the decodes are faster when the RF Gain is backed off under noisy conditions, and of course the WSPR waterfall is cleaner, showing less fuzzies. I would suppose that this is because the AGC is not continously attacking the noise impulses, and obliterating the WSPR signals in the process........   73 to all for now, and good monitoring to you: 


Andy - KU4XR - EM75xr - Friendsville, TN. USA
LOWfer Beacon " XR " @ 185.29875 KHz ( QRSS-60 ) - TEMPORARILY OFF
Coordinates:  N:  35º 43' 54" - W:  84º 3' 16"
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