JT65 Operation on 60 meters

Mark - NU8Z

My question relates to JT65 operation on the 60 meter channels and the problem of the TX inhibit not allowing transmission due to out of channel operation which is influenced by the shift and the TX filter width setting. I have played with the filter settings and have come to the conclusion that there is only ~1000 hz of bandwidth between the lowest freq and the highest freq available for transmission without tripping the TX inhibit on 60 meters. ( I may be wrong? See question #2) 

Question # 1: Are my findings correct? Is only ~1000hz of the channel bandwidth available for JT65 transmission on 60 meters?  If so, I can only work the stations that are transmitting within this ~1000hz sweet spot. This leaves many of the stations I decode unavailable to work without tripping the TX inhibit. 

Question #2: If my findings are not correct what I'm I doing wrong? I'm I missing something or doing something wrong? 

Question #3: If my findings are correct, and it is a fact that the TX range is significantly limited, will SmartSDR be revised in future releases to correct this?  Based on the frequency of the other signals I'm observing, other radios do not have this limitation.

I recently got the 6300, just tried JT65 on 60 meters last night and discovered this issue. Missed two DX stations on 60 meters because I was unable to TX! Ouch!! 

Just for info, I'm running WSJT-X with JT Alert. SmartSDR is in the DiGU mode with TX bandwidth filters being 500hx (lowcut and 2900hz highcut)  Tried other TX filter setting and these allowed for most bandwidth. Also use USB with no difference. I have no JT65 issues on other bands with 100hz (lowcut) and 3000hz (highcut) settings. 

Help!

Mark NU8Z


       

DrTeeth

Are you aware of the USA allocation on 60M? Your questions infer that you are not. Please give info on which frequencies you are trying to TX.

George KF2T

Check your TX bandwidth -- you may need to cut it back to ensure that all emission stays within the channel. Or at least what the rig "thinks."  There is some controversy about pretty much any mode by USB on 60m, with some saying it is a natural for narrowband modes like JT9, etc, where we can run like it's a miniature band with many users. Others say one user per channel, centered, is what the regs say and thus the law. While unquestionably the rules say that, I'm not so sure that was the intention. Have not seen clarification from the FCC.

Bob K8RC

From: http://www.arrl.org/60-meter-faq  (emphasis added)

"Effective March 5, 2012  the FCC has permitted CW, USB, and certain digital modes on these frequencies. The National Telecommunications and Information Administration (NTIA) is the primary user of the 60-meter band.

The FCC Report and Order permits the use of digital modes that comply with emission designator 60H0J2B, which includes PSK31 as well as any RTTY signal with a bandwidth of less than 60 Hz.

The Report and Order also allows the use of modes that comply with emission designator 2K80J2D, which includes any digital mode with a bandwidth of 2.8 kHz or less whose technical characteristics have been documented publicly, per Part 97.309(4) of the FCC Rules. Such modes would include PACTOR I, II or III, 300-baud packet, MFSK, MT63, Contestia, Olivia, DominoEX and others.

On 60 meters hams are restricted to only one signal per channel and automatic operation is not permitted. In addition, the FCC continues to require that all digital transmissions be centered on the channel-center frequencies, which the Report and Order defines as being 1.5 kHz above the suppressed carrier frequency of a transceiver operated in the Upper Sideband (USB) mode. This is typically the frequency shown on the frequency display."

If "other stations" are not centered as required, you are out of luck.

73,
Bob, K8RC

Andrew O'Brien

Bob is correct. you need to be exactly centered to comply with USA requirements AND only one QSO on that channel at a time. 

Mark - NU8Z

Gents
I thank you all for the comments and input. When I experienced the issue, there were a number of JT65 signals within the channel boundaries. None were on the same frequency. I now understand the requirements as pointed out in your responses.  The signal must be centered within the bandpass.

Sorry for the confusion on my part. You learn something everyday!!  
Thanks again to all.

73 Mark
NU8Z

DrTeeth

Andrew, are you saying that according to the FCC regs, there is only one frequency that US hams can use per 'bandlet', where other countries, like the UK, can TX wherever we can find room as long as we do not TX outside the bandlet?

KY6LA_Howard

That is correct. The USA has lots of less than optimal rules ...PLUS we have lots of Old Ladies with Clipboards called Official Observere who are chomping at the bit to cite you if you dare stray from that single frequency. A number of my friends have been cited.

DrTeeth

I have also heard that you also have quite restrictive rules about new modes too; having to forensically dissect rules to see what is allowed and what is not. Luckily, we have no such restrictions. That is useful to know for US contacts.

There is something that I have always thought strange about UK regs; I cannot use a cypher, but I can converse in a brand new mode or speak a rare language. I cannot see the difference.