Tomato Tomahto

Robert W5AJ

it’s another reason why use FSK data mode – the rig handles it  


The rig automatically handles if lsb or usb (LSB for RTTY) and has tones and filters all setup

no brainer

easy in contest….


If your rig has a DATA mode, pick the ASFK or FSK mode and move on

Typical, widely accepted, and/or standard is LSB



The original question was  “What is the convention USB /LSB??”


it’s LSB (can you do USB, clearly yes – don’t – stick with the convention of LSB and get on the air)


73 W5AJ



Midland, Texas


From: [] On Behalf Of Ralph Mowery via
Sent: Thursday, October 08, 2020 9:39 AM
Subject: Re: [MMTTY-SB-RTTY] RTTY nets?


When using a ssb transceiver it does not matter which sideband is selected if using an audio only interface.


Due the the way ssb and audio tones work for rtty you select the sideband you want to use and then normal or reverse mode on the demodulator.


For normal ham rtty of 170 hz shift it does not even matter with in reason what audio tones are used as long as they are 170 hz apart.  Just your dial frequency will be different than others.  Just do not use tones much below 1500 or above 2200 hz.  Too low and the sideband suppression suffers and too high and the power output will suffer.


Normally you use lsb and 2125 for the mark tone and 2295 space tone  and normal for on the demodulator.


You can use usb and 2125 and 2295 space tone for the mark and reverse on the demodulator and there is no difference.  


The only reason for 2125 for the mark tone is many of the older demodulators used fixed filters and either AM or FM audio is used mainly on the 2 meter and higher bands where they are legal modes.


There are some operating military style on the ham bands.  I am not sure what they are using,but think they use USB, normal on the demodulator and 850 hz shift.  If trying to use that mode, set the mmtty or other interface for the low tone option.  I don't recall the audio frequency to use, but again you could just use 1200 hz and 2050 for the audio tones.  Just your dial frequency will show different that the other stations.


Ralph ku4pt




On Thursday, October 8, 2020, 09:06:56 AM EDT, Kai-KE4PT <k.siwiak@...> wrote:



You can use Upper SSB (on all bands, like every other digital mode on the planet) but in MMTTY make sure that "REV" for reverse is selected.
The Detailed explanation: the MARK tone must be the upper tone when viewed at RF on a spectrum analyzer.
Kindest regards,
Kai, KE4PT


Kenneth Williams

Since this topic just begs for comment, and rightfully so, I feel compelled to add that using FSK mode on ones rig is not necessarily a slam-dunk.  I know that some rigs have a software setting that allows one to select if key-down (switch closed) is a MARK or a SPACE, and I believe that this setting is not consistent among manufacturers.

Personally, I got so confused when setting up for RTTY, that I hooked a scope to my rig to monitor the output frequency, went through the settings on both MMTTY and my rig (TS-570) to see what settings gave me what results.  I am not recommending this but it was the only way I could be sure that I really knew what I was sending.