Re: DIY build your own N5ESE Ballpoint Pen RF Probe for cheap. Prefer a Sharpie RF Probe, yes we have that one, too.

Jerry Gaffke
 

I'd like to see some sort of RF probe built into the main board of the Bitx40 on any new PCB rev.  At least pads and traces laid out for it, to optionally be stuffed with parts obtained by the user.  Could be the N5ESE probe, though the $10 AD8307 chip would give far greater dynamic range as suggested in post 20308. Either way, the DC result goes into a Nano ADC pin.

OK, while I'm on a rant, here's some other debug tools that would cool to integrate into the rig.  Having such tools available to everyone that owns the board would make debug in the field much easier, and also simplify things considerably when giving help within this forum.


A basic DC voltmeter, going into a Nano ADC pin.

Use a Nano counter-timer output plus resistor attenuator to give a 1khz square wave (better, a PWM sine wave plus RC filter) of known amplitude into the mic input for transmitter testing.  Perhaps a two-tone test signal?

Use a Nano counter-timer plus a 74HC4040/74HC393 prescaler to implement a frequency counter good to 30mhz.  It's ok if it takes 30 seconds to get 1Hz resolution.

Use a spare Si5351 channel as an RF signal generator, can be set to any HF frequency.  A resistor network gives a selection of appropriate signal levels for injection into the various receiver stages.   (The A and C channels have good isolation and would go to the VFO and BFO, each with their own PLL.  The B channel is normally shut down to avoid crosstalk, but can use its fractional divider to generate a wide range of frequencies from the BFO's PLL.)

And furthermore!:  The Si5351 should be on the main board.   Users can use the preprogrammed Nano and 16x2 display from HFSigs, or choose any uC and display they want.  The relays strike me as relatively expensive and unreliable, all but the T/R switching into the antenna could easily be done in silicon.  At  ~10W signal levels, the TR switching could likely be handled as well.

Don't get me wrong.  The Bitx40 is a real bargain exactly as it is.  But making some basic debug tools available to everybody that owns the board would give us a common way of looking at things, greatly simplifying incorporated into the design would be cheap and give us a standard way 

Jerry, KE7ER


On Wed, Feb 1, 2017 at 08:52 am, Jack Purdum wrote:

I just bought this RF probe:

 

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