How to adjust AGC threshold?

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I was wondering if others would share how they adjust their AGC threshold? I have been adjusting it down until 'most' of the background noise is gone but I feel like I might be missing something. I'm always afraid if I lower it too much I won't be able to hear weak stations. I guess what I really would like to know is where is the point when increasing AGC-T that you are only making more noise and not more signal?

Thanks for your advice.

Jon...kf2e
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Jon - KF2E

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Posted 4 years ago

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Jon W1JDB

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I can't give you a purely technical response as I am not an Engineer. I do it by feel and looking at the waterfall and listening to the noise floor. I adjust the level down as you do until the weaker signals pop out of the noise floor. If I find that I am not copying completely I then raise the level just a bit to see if there is improvement.

As I mostly do digital (PSK mostly) I have found the settings to be easier than with voice. I lower the AGC until the signals show (based on the weaker ones) with minimal background. Then I raise it a bit to give me some headroom and use the DAX RX gain to make fine adjustments.

My 2 cents...

73

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Tom

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Jon,

   Here's how I adjust my AGC, DSP, Preamp and cw filters, for weak signal cw on my F6300. This is real world adjustment.....find yourself a weak signal beacon on 10M, one where you can see the signal on your waterfall but just barely hear it in and out of the noise or see it on the panadapter. I usually start with a "FAST" setting, then adjust your AGC and DSP for best signal-to-noise. This may take a few minutes to do, considering possible QSB.  
I would also like to mention that in my opinion there is still too much noise and ringing when using
the 100, 50hz filter, and narrower settings. I've said this before and hope it is being worked on. 
Tom
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Lee

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Tom,

Not sure how that can work? Here anyways each band has a different requirement for AGC TH.

I fins I have to adj it regularly based on band conditions.

Lee

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Tom

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Lee,
   Yes, you are correct, I should have clarified that my method is not meant to be a 'one-fits-all' but a good way to practice with all the tools we have at our disposal. Using a weak beacon that will be a constant signal seems to me to be a good place to start. 
Tom
 
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Tom K3TF

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Jon,

I am a CW operator and here is what I do.

1. I always run headphones. Use a good pair of headphones that do not ring at narrow filter settings. Some headphones will keep resonating or ringing.Speakers tend to cause sound reflections and ringing at the narrow filter settings.

2. I run a higher cw pitch setting 700hz. The human ear is non-linear and can resolve tone frequencies better at higher settings. I can not hear the difference between 500 and 510 hz but I can hear the difference between 700 and 710 hz fine. Being a musician helps!

3. I always run with the 50 hz filter on CW. Improves the signal to noise and then you do not need the NR, NB, APF. CW is a single tone, usually depending on the other guys transmitter and a single tone will easily fit in the 50 hz window. 

4. Now to answer your question. Crank the AGC T all the way to the right. Set audio level slightly higher than you normally use. Now crank the AGC T back until the other station sounds good. 

I find the control I am always adjusting is the AGC T, not the volume control when I have it set correctly.

Oh, i always run Fast AGC. 

Just my thoughts, others may have different approaches. Treat the AGC T like it was an RF gain control on an old fashioned receiver. 

73, 
Tom
K3TF...............
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Tom

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Tom,

Thanks for the specific info......looks good. I see that Walmart carries them so will go over and check it out.
73, Tom
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Jim - N7CXI

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Walmart carrying AKG... There's something very wrong about that.
--jim (N7CXI)
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Tom

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   Well, I thought I saw them listed on the Walmart webpage with a few review comments, so I visited our local Walmart today, which is only a few miles away. Not seeing any AKG brand, asked a sales rep, who didn't know of the brand. 
Tom 
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Jim - N7CXI

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I just looked and didn't see any on their website.
Originally, I was just growling a bit. AKG has in the past been a premium brand, and you got premium quality and performance for the price. Imagining the brand being turned into a consumer commodity by WalMart was a little tough.

--jim (N7CXI)
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Tom

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Jim, I can understand :)