17 METERS SPECTRUM

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  • Question
  • Updated 4 years ago
HI ALL. I have the Flex 6300 finally hooked up and in going through the bands I noticed that on 17 meters the top of the spectrum is only 18.164 after that I cant tune or key. Where can I change that setting? VA3KBC
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Don Stefanik

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Posted 4 years ago

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Larry Loen WO7R

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If you tune to 18.164, you are at the top of the _usable_ band because your "upper sideband" signal will top out around 18.168 (at least under US rules)
(Edited)
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Don Stefanik

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hhmm with my pro3 I could go right to 18.168  there are a few guys I would talk to on 18.165.

so now I won't be able too?


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Andreas Junge, Elmer

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Have you tried to reduce the TX bandwidth? Maybe you are at 4KHz right now?

Try 3KHz. Just a guess. 

73, Andreas, N6NU
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Ken - NM9P

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@Don...Many rigs limit TX output based upon the base carrier frequency, which then allows the upper sideband signal to go out of band.  The frequency limits in the rules require the signal to be limited based upon actual signal output, rather than carrier frequency, which is off by the by the amount of transmit bandwidth either above or below the carrier frequency.  The same goes for spurious emissions.  If a guy is right at 18.168 carrier frequency and using LSB, it is OK, as long as there are no splatter or other modulation byproducts in the opposite (upper) sideband.

Ken - NM9P
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Mike va3mw

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On my 6300, I can tx on 18.165 with a low cut of 100hz and a high cut of 2900.  If I increase it to 3000hz then TX is disabled.

I bet your bandwidth is higher than 3k.  No real reason to make it higher than that other to use bandwidth you don't really require. 

The radio is working as designed.  

The Pro 3 was more generous, however it is up to you to ensure that you do not transmit out of band.  It is more than the carrier frequency that we look at on our dials.  That is something that a lot of new hams don't always understand (or remember).  It was likely one of those test questions.  :)

Carrier freq is 18.165 + up to 3khz of audio takes you to 18.168.  Beyond that, you are out of band even without moving the VFO.

Mike va3mw


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Don Stefanik

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Ok. Got it thanks.