LOWE HF225 mute's at 11 MHz
 

recently my HF225 mute's reaching 11Mhz while tuning the vfo, or
while using the keypad!
When I use the 1Mhz knob 10- 11-12-13-14_15(sound again) The radio
mute's at 11Mhz until 15 MHz

although when switching off the set while i am in te trouble area
(11-15MHZ) and power on again. the radio works just fine!

Could it be the diode D1 needs replacement

tanx for your time
regards
bram