开云体育

Hmm, my analysis in post /g/BITX20/topic/6215251
might be full of beans.

The SiLabs document an619 shows that registers 16,17,18 can set drive
levels at clk0,clk1,clk2 to values of 2,4,6 or 8 ma.
With 8ma max into 50 ohms that's a 0.008*50 = 0.4v pk-pk square wave
across the 50 ohm load.
Farhan's ubitx has a 6db pad between the raduino and T1, so the primary
of T1 sees 0.4v/2 = 0.2v.
T1 has two windings driving the diodes, a step-up transformer, so the
diodes see a 0.4v pk-to-pk.
But a single schottky diode has a forward voltage of around 0.4v at
10ma, I have no idea how this
0.4v signal source can drive two schottky diodes in series.

But the ubitx apparently works.
What am I missing here?
I'll have to put a 50 ohm load on a si5351 someday, see just how much
drive the si5351 can give.

Might be best to include a buffer amp, if only to reduce all the
crosstalk you would get between si5351 channels
when asking it to deliver maximum drive.



On Mon, Oct 23, 2017 at 02:54 am, Gordon Gibby wrote:

think you're off a decimal point there.... 2 mA into 50 ohms is 1/5
of a milliwatt so it wold not be 3dBm....

------------------------------------------------------------------------
*From:* Kelly Jack <kellyjack1968@... *Sent:* Monday, October 23,
2017 5:30 AM
this page indicates that setting the drive at 2ma equates to 3dbm
into a 50ohms load.

<>