[GreenKeys] Getting RTTY on the air

[Duncanancy]

I had uneven tones the first time I tried putting AFSK tones into my SSB TX.  It turned out that my higher tone was being cut off by the SSB filter!Something else to check.Good luck &have funDuncan K2OEQ Sent from my Kleinschmidt TT-4/TG, the US Army's first portable digital communications device, 1950-1980
-------- Original message --------From: Harold Hallikainen <harold at w6iwi.org> Date: 11/10/20  23:31  (GMT-05:00) To: kn7sfz <kn7sfz at gmail.com> Cc: greenkeys at mailman.qth.net Subject: Re: [GreenKeys] Getting RTTY on the air Thanks! I just recorded my signal off a websdr and then tried playing itback into the TU-170. Didn't work! But receiving ITTY works. I checked thetransmit tone frequencies yesterday, and they looked good. I noticed thatthey are not equal level, though. I'll look at the receive signal on ascope and see if I can determine anything. The TU-170 did not even key theloop on my signal.Time for debug!Harold> Hi Harold,>> I think RTTY has been relegated to below 3600 now...sniff.....>> I believe there might still a RTTY group (RATTSNET) that meets in the> evenings on the left coast here on 3598, LSB.  I quit listening to them> when they changed to Olivia, so I dunno if they ever changed back.>> I'm sure some of the other gurus here on the list can fill you in on > your technical queries.>> Keep us updated!>> Richard kn7sfz in Orygun>> On 11/10/2020 6:59 PM, Harold Hallikainen wrote:>> I've finished connecting my model 15 to the TU-170 to my radio (>> https://w6iwi.org/SEA245/ ). I added an audio transformer and a reed>> relay>> to the TU-170 to drive the SEA245 tri-state audio bus. For testing, I'm>> trying to get the RTTY decoder on a KiwiSDR ( http://rx.linkfanel.net/ )>> to decode my signal. So, here are some questions.>>>> 1. I remember from MANY years ago, that LSMFT, or Low Space Makes Fine>> Teletype. That, as I recall, is on RF, and it's reversed on AFSK. So,>> the>> TU-170 uses 2.125 kHz for mark and shifts up 170 Hz for space. That>> indicates that the transceiver should be set for LSB to get the signal>> right side up. Is this correct?>>>> 2. How is the transmit frequency normally specified? I can think of>> several ways:>>>> a - Mark frequency>> b - Center frequency (Mark frequency minus 135 Hz)>> c - LSB "carrier frequency" (Mark frequency + 2.125 kHz>>>> Is one of these correct? If so, which one?>>>> 3. What are common frequencies on the HF bands for RTTY? From many years>> ago, I think I remember 3.635 MHz for the mark frequency.>>>> 4. Anything special in the FSK settings on a KiwiSDR? Should the signal>> be>> inverted?>>>> THANKS!>>>> Harold>>>>>>>>-- http://w6iwi.org______________________________________________________________GreenKeys mailing listHome: http://mailman.qth.net/mailman/listinfo/greenkeysHelp: http://mailman.qth.net/mmfaq.htmPost: mailto:GreenKeys at mailman.qth.net>>> Jordan Spencer Cunningham's GreenKeys Search Tool: https://teletype.net/gksearch>>> 2002-to-present greenkeys archive: http://mailman.qth.net/pipermail/greenkeys/>>> 1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html>>> Randy Guttery's 2001-to-2009 GreenKeys Search Tool: http://comcents.com/tty/greenkeyssearch.htmlThis list hosted by: http://www.qsl.netPlease help support this email list: http://www.qsl.net/donate.htmlMessage delivered to duncanancy at earthlink.net
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