[RTTY] 80M DIGITAL SUB-BAND in JA

[Bill Turner]

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On Fri, 17 Oct 2014 17:21:32 +0900, 7L4IOU wrote:

>
>I was asked about the activity of 80m RTTY in JA by several guys.
>We can Tx RTTY signal at 3.520-3.530MHz and 3.599-3.612MHz on 80m band.
>
>https://www.jarl.org/English/6_Band_Plan/JapaneseAmateurBandplans20090330.pdf
>
>and Many JAs wants RTTY DX QSO on 80M.

REPLY:

Antennas on 80 meters can be a problem, SWR-wise. If your antenna
covers 3520-3530 then you should probably operate there. But not all
antennas do and the higher segment may be a better option. 

In the higher segment mentioned above, US hams can transmit only
within a 1 kHz segment:  3599 to 3600 kHz.  Be careful with this. Most
of us using FSK have transmitters that show the mark frequency, so you
should put the mark slightly below 3600. That way the space frequency
will be 170 Hz down from that, which allows the JA's to reply on your
frequency and still be within their segment. Allowing for sidebands, I
would recommend US stations go no higher than 3599.900 for the mark
freq. 

Another consideration is that if US stations have their mark freq at
3599.170 or below, the US station will be legal but the JA station
will not. Strictly speaking, because of sidebands you should be even
higher than that. I would suggest a mark freq of 3599.300 as a minimum
and a bit higher would be even better just to be safe. I don't know
how picky the JA authorities are about sidebands, but better safe than
sorry. 

Folks using AFSK need to do the math VERY carefully!

I'll be using 3599-3600 myself.  Hope to see you there. 

73, Bill W6WRT