A diode-pumped Q-switched ${\mathrm{Tm}}^{3+},{\mathrm{Ho}}^{3+}$ -codoped double-clad silica fiber laser is reported providing average powers of up to $12.3\mathrm{W}$ at $2072.7\mathrm{nm}$ and stable pulse widths of only $45\mathrm{ns}$ and repetition rates in the range $10–100\mathrm{kHz}$ . Instabilities in pulse shape occur at nonoptimum cavity alignment and were found to be linked to the mechanism responsible for self mode locking.