TX Filter Settings for FT8?

Neil D Friedman N3DF

I enjoy operating my 6600M on FT8 with reasonable success.  The radio is set to DIGU at 5 kHz.  My question is this:  the transmit menu (i.e., pushing the mic/speed knob) is set to 100 low and 2900 high.  Is this wide enough for optimum FT8 or should the settings be wider apart?  Do these settings matter?Thank you for any advice.

Duane_AC5AA

They do matter, I believe.  Set it as wide as possible.  I usually use 3K bandwidth but you could set it for 4K since I think that's the upper limit of what FT8 decodes.  Now, someone can tell me I'm wrong.  Oh, and I have been using USB rather than DigiU simply because that's where it opens when I use FT8 software to change bands.  I'll let someone straighten me out if needed! 

KY6LA_Howard

Definitely use DIGU not SSB because DIGU disables DSP


The FT8 XMT signal is actually quite narrow but I usually have mine set from 0 to 3000 to match my RX albeit I generally stick my TX Frequency to a fixed frequency and I do not follow the RX Frequency  Work a lot more DX by not transmitting on his frequency

WD4EGF

I let WSJT control the 6600 via cat. It then shifts the tx freq and tone freq to keep it close to the center of the tx passband during tx. The other station cant tell this was done, but it keeps your output consistant at any given tx tone freq. I'm away from my rig until late friday, but can provide more specifics if you like then. 73, Don, wd4egf

KY6LA_Howard

Don


You are thinking Legacy Radio.. SDR's don't care where you transmit

Best Advice is to look for an open TX frequency and set the radio to transmit there so that you are not doubling with someone else.. That way the DX Station will copy you in the clear.

In the first year of FT8, worked 201 countries and 173 confirmed doing it that way so results matter...

WD4EGF

Good afternoon Neil. I did a few quick tests this morning. As Howard indicated, DigU is the way to go with these radios. I used the tune function on test tones from 200 to 5000hz. In DIGU the response is flat, regardless of the TX Audio filter settings. These do come into play if you are in SSB only. These tones are the limit for WSJT output though the Flex may respond wider, but i didn't persue further. The action I was referring to (tx freq shifting) can and should be used on 'Legacy Radios). The actual tx freq is then centered in the tx passband. This is enabled by setting 'Fake It' on Split Operation in WSJT's Radio setup tab, and having cat working. The feature is really intended, i suppose, for EME op, to allow for doppler shift. Howard, FB on working split. Yes, thats how I work as well. If i dont get an answer after a few calls, i'll pick another, clear (Hopefully to the DX) freq, often making the contact. I've also been hearing more dx using Fox/Hound too, works vy well, and uses split dynamically. Sweet 73 Don Wd4egf

Neil D Friedman N3DF

Don, at present, when i see a station i want to work, I move my receive and transmit to his or her frequency.  Are you saying I should move my receive frequency while leaving my transmit frequency where it is?

Duane_AC5AA

I misread your question on the first pass.  Your "listen" frequency isn't really that important - it just allows the station there to be printed in the right column.  You should place your TX frequency in a clear spot.  What happens today is a lot of folks double-click on the station calling CQ, which places both TX and RX on his frequency.  Now when transmit time comes, all are sending on the same freq, making a mess.  Find a clear spot, do a "Shift-Click" of the mouse to move the TX frequency there, and try that.  Remember that the frequency may sound clear to you, but may not be at his end, so if you don't connect in a few turnarounds, try another spot.

WD4EGF

Neil, check your 'Hold Tx Freq' box. When you double click a station, they will be moved to your right window pane, and i think enhance the sensitivity to their signal(?). Also, your tx freq remains the same, at your 'clear' freq. Like Duane said, its a mess otherwise. GL and 73 Don

Neil D Friedman N3DF

I did not realize that my transmission would appear in red to the station I am calling regardless of my transmit frequency.  This is helpful.  Thank you.