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Without the BS170’s my receive current is the same. ?I am measuring the current from center pin of power connector with + probe and touching the - probe to the ground of coax. -- Marc N8LO

I would put getting the RF out of your power supply high on the priority list.? First rule of troubleshooting is to fix what you know is wrong. I would not be comfortable with my power supply voltage

OK, so I pulled the BS170’s and made a simple circuit to test them. ?The LED lights up on all four. ?Is there a better test? -- Marc N8LO

This will be an informative article for you. A DDS VFO for the TS-520S | KV6O ( https://www.kv6o.com/wordpress/2014/10/10/a-dds-vfo-for-the-ts-520s/ )

I think Colin meant *Re: QDX v3 Lost transmit on 20/30/40* From: Colin Kaminski ( colinskaminski@...?subject=Re:%20QDX%20v3%20Lost%20transmit%20on%2020%2F30%2F40 ) Date: Sun, 14 Aug 2022

Willie, This first step is to do a very close and?thorough inspection of the board for shorts or bridges between traces. What happens when you use the Terminal Transmitter Test program?? Does it

Thank you Hans, It took me a few days to check everything. I am only using the built in tools. They have changed since the manual and I didn't notice the scale changes till today. I am using a Rev 3

OK, so it's only one way, but it adds evidence that this little QDX - no bigger than a pack of cigarettes - has a good transmitter indeed ! Over the past 24 hours, I've made probably 50 or so 2-way

Just some final thoughts after rethinking and calculating the levels. When using a BS170 buffer you come up with something like 150mW output RF power on 50 Ohm.? This is the RMS voltage around 2V.?

Please have in mind also that the Si5351A CLK0 output is a square wave 5V signal with a 2.5V DC component.? TS VFO input must be a sinus AC signal.? So don't forget C1 to decouple. 73 Bojan S53DZ

Thanks Evan, I will pull the mosfets and test them. ?Hope that fixes my issues. ?I will let you know how it goes. -- Marc N8LO

But, no matter what that test might show to you I would suggest you do the buffer amplifier with BS170 to protect the Si5351A output. 73 Bojan S53DZ

Hans, In your design of the BPF (L12), did you assume, or measure, stray circuit capacitance? My calculations, using a nominal AL of 4.9nH per turn squared, suggest that the capacitance values need to

Hi Al, Thanks for pointing that out. I'm aware of the voltage drop and this is a price I'm willing to pay at the moment, I compensate with a bit higher voltage if needed. :) I can estimated by

Bertel, The Elecraft W1 power/SWR meter is the most RELIABLE. Charles Brown N4SO

Yes it can be connected but in that case it would not be 1V any more.? If the rig needs 1V rms at 50 Ohm then you still have to do. Anyway you can connect the CLK0 over C1 direct to the LPF input and

ON Semiconductor bought Fairchild. Same parts, different name. Individual builders generally have no reason to care whether the parts are loose or tape and reel, so buy whichever is cheaper or easier

Bojan, Have installed all capacitors C1, C4, C5, C6 C8 Jumpered W1-W0 and W2-W3. Jumpered PA to 5v+ Installed R6 Installed Q1 BS170/// Assembly instructions says Q1 and R5 pot not required for the VFO

Hi there, Yes, this was also my concern.? 74LVC2G17 propagation delay is around 3.6ns.? So it is on its limit already. But I was quite happy with the behavior.? The limit of my osciloscope is at

Bojan, I have been thinking of doing something similar to that.? However, I have a comment about the spectrum.? It has rather high levels of even harmonics.? A square wave should have very low