TX Band settings

Transmit Audio Bandwidth – generally most HF transmission take the standard rule of thumb to stay within a 3khz bandwidth.  So for the new hams this means your audio fidelity would be from 0 to 3000 hz, or that of a typical phone call. Plenty good for voice communications, obviously not CD quality. AM broadcast transmission can go up to 10khz, but are typically in the 4 to 8khz range depending on the station.  FM goes all the way up to 15khz typically and thus sounds even better.What I’ve noticed is that most rigs default to about 2.7khz bandwidth on transmit. Nothing wrong with that but if 3khz is allowed and accepted why not maximize it for improved sound quality. Looking at my waterfall the vast majority of what I see these days is 3khz wide. Some rigs even allow Extended transmit bandwidths, and we call that ESSB. ESSB is for those transmissions exceeding 3khz up to 4 or 5khz. I’ve seen higher, but honestly doing so wastes precious frequency spectrum for others to use. If the band has little activity then it’s more acceptable but I would never recommend exceeding 3khz during crowded areas or contests. And for the record, I’ve had many QSO’s at 4khz wide, but the band was underutilized and I made an effort to not bleed into any nearby signals.Tradeoffs of wider transmit bandwidths. For one thing with a wider bandwidth, your transmitter is using the same power limits to energize a wider area of RF signal. This means if you are trying to work a weak station, they may have more difficulty hearing you. By reducing the bandwidth back down to 2.7 or 2.1 khz that 100 watts out of your rig will concentrate more of its energy to the signal you transmit. Take note too, that reducing the low frequency transmit bandwidth is just as important. If you have the ability to cut audio frequencies below 300hz this will reduce the low frequencies in your voice having to be transmitted wasting energy that’s not necessary to be understood . You might sound tinny but your transmitter will use all of its available power to generate a signal and concentrate that energy where it’s most needed to be heard. So if you want to get through a pile up or a marginal signal or in an emergency then reduce the bandwidth to make the contact.But when you’re not in contest mode, then enjoy the better sound quality of a wider bandwidth and open it up to 3khz, just be considerate of others if your experimenting with ESSB beyond 3khz.

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Hi Don, those settings set max RF power, Tune power and what jacks on the back are active when the PTT or key is activated. The PTT Inhibit prevents you from keying the radio on any bands that have it checked. So if you had an amplifier with a PTT input, you could check RCA TX1, then plug an RCA cable from the TX1 jack to the PTT input of your amp. Now anytime PTT is asserted (including tune and key closure), you will also key the amp. The last column is for hardware ALC in case you have an amp that really needs it.

I hope that helps.

73,

Len, KD0RC