It really is a nice radio. In AM mode for transmission, with the low level modulation, it isn't the greatest for that mode (there are mods to improve AM ALC reaction found on the NET). Really nice in SSB but its only capable of about or a little over 3/khz transmitted bandwidth. If "eSSB" is what you're looking for, there are better choices, nice receiver though.
with a schematic diagram and knowledge, you can easily modify the AM AF bandwidth for TX.
most low level modulation transceivers utilize an IC for low level AM/SSB modulation like the SN16913, its as simple as finding the input pin, disconnecting the rest of the audio circuit prior to it and connecting your own input, its the audio amp circuit prior to this input pin which changes the AF frequency response.
the Yaesu FT-757GX (MK1/MK2) is an easy example of this, you can achieve as low as 20Hz and as high as 20Khz AF though i dont really see a reason to go beyond 10Khz AF for music/speech, with this radio, its as easy as disconnecting the copper trail to the input pin and adding a 50K input resistor (leaving the tantalum caps and 100K resistor in place for input balance), this will allow you a 0.5VPP input with an AF range of 20/20 for AM TX though i recommend using an AF filter to cutoff anything above 10Khz.
with this type of knowledge, you could TX in more modes than just AM/SSB, a few examples of additional modes are DSB (USB+LSB) or a choice of upper/lower suppressed AM.
when it comes to modulation, the limits are only set by the design of transceiver that you use.
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