IK3OIL FREQUENCY LOCKED LOOP FREQUENCY COUNTER
PCB SET VFO AND FREQUENCY COUNTER
A little device which joins in a single microprocessor a digital programmable frequency meter and a control logic capable to lock a manually tuned VFO to its actual frequency.
The locking function is software inhibited when a manual tuning is detected, so as to provide a completely automatic working.
Technical Features of the FLL
Frequency stability aligned to the reference crystal, with a maximum +/- 15 Hz drift
Digital frequency readout, with programmable IF value and 10 Hz resolution on the LCD display · Manual frequency tuning, trough a multi-turn potentiometer ·
Automatic Lock/Unlock function, unlock status is signalled by a LED diode and entered during manual tuning or in case of an excessive VFO drift ·
Programmable lock range. It is the maximum allowed value for a “short term” (0.2 sec) frequency shift without exiting the locked status. This improves the capability to suit to various VFO circuits. ·
The overall (long term) drift compensation capability is limited to about 15 KHz (+/- 7.5 KHz), normally enough to stabilize a well assembled VFO, however I suggest not to exceed a 20/25 MHz limit, although the counter capability may reach 35/40 MHz
IK3OIl FLL frequency counter and microprocessor controlled VFO stabilizer being used successfully in many of our Bitx Kits.