  The production of K$^+$, K$^-$ and $\varphi$(1020) mesons is studied in Al+Al
collisions at a beam energy of 1.9A GeV which is close or below the production
threshold in NN reactions. Inverse slopes, anisotropy parameters, and total
emission yields of K$^{\pm}$ mesons are obtained. A comparison of the ratio of
kinetic energy distributions of K$^-$ and K$^+$ mesons to the HSD transport
model calculations suggests that the inclusion of the in-medium modifications
of kaon properties is necessary to reproduce the ratio. The inverse slope and
total yield of $\phi$ mesons are deduced. The contribution to K$^-$ production
from $\phi$ meson decays is found to be [17 $\pm$ 3 (stat) $^{+2}_{-7}$ (syst)]
%. The results are in line with previous K$^{\pm}$ and $\phi$ data obtained for
different colliding systems at similar incident beam energies.
