Look at the schematic for the Bitx40.
Long ago, the "Tuning" connector went out to a pot, was used to apply a DC voltage to the varactor diode at D9.
But that analog VFO was not stable enough.
The solution was to add the Raduino in late 2016, all Bitx40's shipped from Dec 2016 on went out with
a Raduino, and with L4 removed.? The Raduino injects a VFO signal into the "DDS" connector,
and with L4 removed the caps at C93,94,95 and D9 are removed from the circuit.
The si5351 on the Raduino is what determines the frequency of the VFO.
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On Sat, Nov 24, 2018 at 06:56 AM, Scot McMath wrote:
Looking on the components side of the Bitx 40 board right side about 1/2 way, I see a 2 prong connector labeled TUNING. My instruction sheet from HF Signals shows nothing, no connections. anyone have any idea if this is connected and where to?
