Switching ON and OFF of the VBF always interacts with RGO ONE receiver Automatic gain control system (AGC). Since VBF reduces noises in RX path – from the ether and from previous IF amplifier, AGC system will act slightly different. Let’s discuss these cases:
1. VBF is not in use (or not installed) AGC treshold is aligned with R26 on IF/AF board in order to obtain S1 or no indication on S-meter. (This procedure has been already done by manufacturer)
2. VBF is installed and is selected (B01 – B10) via pressing FLT button. IF signal + noise is decreased and then AGC response and action will be decreased. Reading on S-meter will fall down. AGC treshold must be realigned with R26 potentiometer in order to have proper AGC response and S-meter reading. But if you decide to switch VBF off and use standard filter again – S-meter reading will not be valid and R26 must be realigned again.
How to deal this issue.
Suggestions:
1. If you like to achieve best AGC response and you are mostly CW operator and you are using mainly narrow filters – then engage VBF and align R26 to null S-meter reading with no antenna connected to RGO ONE 50 ohm input. First rotate R26 counterclockwise and when S-meter starts to raise – slightly and carefully return back till S1 on S-meter flickers or no segments appear lit on LCD. In order to achieve true S-meter readings – always use VBF – for CW and sideband modes – just increase or reduce bandwith with encoder 1 on the front panel.
2. If you are not using narrow filter much – align AGC treshold with R26 when VBF is off or do not align it if S-meter reading is null (with no antenna connected). Though S-meter reading might not be accurate on some filter bandwiths when VBF is on. Received signal strength won’t degrade or been lost with this adjustment. Just S-meter reading will show some S units.
