| Author |
Message |
    
Mersberj
New member
Username: Mersberj
Post Number: 1
Registered: 8-2005
| | Posted on Wednesday, August 24, 2005 - 10:19 am: | 
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I was wondering if anyone had a picture of how a good waveform (mod envelope?) is suppossed to look like on an O-scope. I wanna start getting back into tuning my radio up and getting the best performance out of it but don't know how to use the Oscope properly.By the way I am the Test Equipment custodian for my ship so I have access to all the test equipment I would need , just don't know what kind of things to look for. Some pics would help .Also easiest way to convert Peak to peak to actual wattage. Thanks in advance |
Hollowpoint445
Advanced Member
Username: Hollowpoint445
Post Number: 702
Registered: 6-2004
| | Posted on Wednesday, August 24, 2005 - 3:16 pm: |
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It should be a perfect sine wave. Check at the bottom of this link. It shows how the waveform looks at various amounts of modulation:
http://www.williamson-labs.com/480_am.htm
BTW - Why don't you just ask one of the folks who uses the oscilloscope how to use it and what to look for? Or RTFM? |
Mersberj
New member
Username: Mersberj
Post Number: 2
Registered: 8-2005
| | Posted on Thursday, August 25, 2005 - 1:00 pm: |
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I am an Electronic Tech on board this Navy ship that I am on right now, I went to calibration school , but I haven't gone to a Comm school. Basic electronic theory is easy but understanding Comm or should I say "RF" is another story. I have seen the envelope on the link you sent , so I guess I am looking to make sure the positve and negative peaks do not flatten (over modulate).As far as measuring peak to peak of the same envelope, could I convert Vol Pk to Pk to Vol Avg or RMS to get Watts out. |
Therealporkchop
Intermediate Member
Username: Therealporkchop
Post Number: 358
Registered: 11-2002
| | Posted on Friday, August 26, 2005 - 6:57 pm: |
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Well welcome first off. Secondly if you don't want to see those nasty little flat tops or lines between the waveforms, don't clip anything and don't install the supermods. They'll all cause this.
Easy way to view the modulation and carrier is to use a capacitive pick point. Get yourself a coax T and remove the pin from the male side. Cut it so that when you re-install it, it's flush with the insulator inside the T. You may need to cut a slot into it so you can use a screwdriver to re-install it. Then get yourself a connector from an old amp and screw it onto the male side. Use the centerpin to connect the center conductor of a piece of RG58 coax and ground the braid to the fitting. Then install a BNC connector on the other end and hook to the scope. You can now view the carrier and modulation of your radio. You should check the stuff first with a volt/ohm meter to make sure it's not shorted out or conducting from the center pin to the coax. You want it to have a few picofarads of capacitance so you don't overdrive the scope. |
