Re: Intermittent REF UNLOCK error message on 8591A Spectrum Analyzer
开云体育Anders, ? So, in green is the active bias stage, R66 serves as the current sense. In my case, I have 5.186V, which means that the collector current of Q13 is about 9.8mA. ? In blue is the oscillator with CR1 as a varicap for frequency control. Now, the frequency range of your circuit is too low, I would be tempted to try adjusting with R68, but make a mark on R61 to note the current state of the adjustment, because if it doesn't work, you can reset it to its original position. Since the frequency is lower than expected, and if R68 doesn't change anything, then the capacitive load is too large, I would suspect the varicap CR1 as the first suspect. ? You can always experiment by disconnecting C81; the frequency should rise higher. ? Yves ? ? De?: [email protected] <[email protected]> De la part de Anders L??v via groups.io ? Thanky you for the valuable information Yves!
? My 300 MHz VCXO range is 299.872 MHz (10 MHz Ref disconnected) to 299.959 MHz (10 MHz Ref connected) - A total range of 88 kHz which is a bit smaller than yours 111 kHz. This time I have meassured the frequency at the Cal Out to make the meassurement easier. ? I have desoldered and checked the R68 potentiometer and it was fine. |