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Author Topic: Some interesting (to me) screen shots  (Read 5234 times)
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w1vtp
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« on: November 15, 2009, 08:35:51 PM »

All

These screen shots were taken the the Peak (hold) function engaged.  I think the first three demonstrate that it is possible to be very tight with our BW control. 

The first is that of a Flex 5000 driving an amplifier to max legal power.  The next two were not -- but seem to have brick-wall filtering with a cutoff of around 4 KC. 

The final two show no evidence of brick-wall filtering.

73, Al

* am_screen_shots.pdf (485.12 KB - downloaded 550 times.)
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N2DTS
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« Reply #1 on: November 17, 2009, 08:57:09 AM »

If you adjust the amplitude steps, you get a better display of the modulation.
I have mine set for about -120 to 55 db I think, which shows the spectrum much better.

I have seen many great looking and sounding signals, not real wide and sounding good, and some not very good looking signals.

You can also see the guys running amplifiers on SSB, or at least the dirty ones.
It looks a little like dsb...


Brett



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kg8lb
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« Reply #2 on: November 17, 2009, 11:22:35 AM »

 So if the Flex 5000 station is 30 over 9 at 3870 folks trying to operate 5KC up or down from him will only have to deal with close to a 10 over 9 interference level ?
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Steve - WB3HUZ
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« Reply #3 on: November 17, 2009, 12:54:00 PM »

Or more since if they are using AM, their RX bandwidth would extend down to 3872 kHz with a 6 kHz IF BW, or about the same if they were on lower sideband - that's 3 kHz into the passband of the other QSO.
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N2DTS
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« Reply #4 on: November 17, 2009, 04:05:12 PM »

I have had many times when 5khz spacing did not cause 'me' any problems hearing any of the 3 qso's without any interferance.
If signals are REAL strong, or someone is very wide it does, but most times it seems not to.

I usualy set my filter at 5.2 KHz because I cant hear any difference above about that, unless maybe in headphones at high volume.
SDR also lets you see the interferance and shift the passband and narrow things up so you can get the same audio quality and nix the interferance.

If I could hear high sounds, I guess I would want wider spacing.
But hearing loss has some benefits, some sounds that drive my wife nuts I dont hear at all!

Brett
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kg8lb
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« Reply #5 on: November 17, 2009, 05:11:12 PM »

  Yes, I have used the continuously variable bandwidth and passband tuning with the JRC NRD545 to do much the same thing. Even the Drake 2B passband tuning can help take the edge offf of broadcrap audio that likes to pop up 10 wide 5 away.
  Very useful feature  in knob and switch or pooter powered receivers.
 
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