Flex6300 Band edge limit

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I am going to raise this again because I am not getting it and it's frustrating me. I will use the 17 meter band as an example here.  The 17 meter band covers 18.068-18.168mHZ (in Canada) but the Flex-6300 will not let me transmit pass 18.165.100mHZ, I was trying to work a station at 18.166 and could not, whereas on my Elecraft KX3 I am able to. What am I missing here, as I can recall this is the only radio I've  had that will not allow TX on the full band spectrum.

Maybe someone can educate me.

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Posted 4 years ago

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Photo of Mike Hoing

Mike Hoing

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Official Response
The Rule

If the band goes to 14350 KHz, then contesters can just set their dials to that frequency and operate- right? Wrong! The crux of the matter is found in FCC rule 97.307, which reads in part: "Emissions resulting from modulation must be confined to the band or segment available to the control operator."

What must be taken into consideration is the fact that the frequency displayed on the radio's digital display is the carrier frequency. A suppressed-carrier single-sideband signal is considered to be 3 KHz wide. So, for an USB signal to be confined to the 20 Meter Amateur band, the frequency displayed on the transceivers digital dial should not be higher than 14347. That may even be too close unless the transmitted signal is attenuated by at least 40 dB at 3 KHz. Of course, the same goes for a LSB signal transmitted near the lower end of a band or segment. Please see illustrations A and B below for help visualizing the situation.

USB Signal
347 14350 353

A. USB signal transmitted with dial frequency of 14350 KHz.

LSB Signal
147 7150 153

B. LSB signal transmitted with dial frequency of 7150 KHz.

So, the fellow telling all the contesters that they were out of band was right! But, is it a big problem? Obviously more education is needed on this particular rule. In the 2001 ARRL DX phone contest one Dx station was heard running US stations on 14349 KHz. in excess of 5 hours straight with a steady stream of US callers. Most were Extra class licensees.

Although certainly the majority of these callers didn_t realize they were violating an FCC rule, the action could result in an FCC warning, ARRL OO notice, or perhaps an argument from a frustrated fellow contester as mentioned at the outset of this article. Since all contesters who submit a log sign a statement that they have followed their country_s Amateur regulations they should be willing to take this rule into consideration and modifying their operation as needed.

In addition, contesting ethics are involved. What if a station finds a clear running frequency by operating too close to the band edge, while his competitor perhaps fails to find a run frequency out of respect for this regulation? Or what if a multiplier is counted by working a station calling too close, while other stations don_t get the multiplier because they want to obey the rules? Perhaps such situations are part of what causes our mystery stations to vent their frustrations.

I hope you find this article of help in your contesting efforts. Further information about this particular FCC rule can be found on page 4-34 of the ARRL_s "FCC Rule Book." See you in the contests.


****This information was copied not of my creation