I have been bitten too by wrong footprint on a board. These days if its a foot print I haven't used, I print the board to paper and wait until I have the part to test fit before ordering. As a side note, I have switched to diptrace for schematic and pcb, in my opinion so much better. they have a free version that is just as powerful and I was able to use it for about a year before I purchased a higher version
I always like to print off the Gerber’s so I can get a good idea whether I’ve got it right or not before sending them off. I can’t always get a feel for the pads on the screen, but on paper and with the parts it’s easy.
I think KiCAD connector footprint is made to use a regular through hole connector. You can usually place it diagonally and then the footprint makes sense.
There are 3 SMA Edge Connector footprints in the standard Kicad library that cover the three main sizes, the one shown here was the first in the list and the largest. Kicad now has a measure tool in its selector so you can double check !
Emissions: “For transmitters installed after January 1, 2003, the mean power of any spurious emission from a station transmitter or external RF amplifier transmitting on a frequency below 30 MHz must be at least 43 dB below the mean power of the fundamental emission.” Sec. 97.307(d) I like your SMA pads; better than a thin pad the iron can’t reach well.
A KiCAD design decision was to put emphasis on a library. I never, ever use someone else's PCB library, and never one that can somehow update out from under you. Of course I don't draw all my own footprints, but if on rare occasion I use someone else's footprint I check it. I've found a personally known good library is an essential design principle. Little things that look right but aren't matter, especially with SMD footprints where surface tension plays a large part in centering the part in automated assembly.
What do you think of stitching vias, to strongly connect both ground together ? That may decrease the ground impedance and increase the filter performance.
for this low frequency I don't think it matters, for higher frequencies yes it is a good idea. here is a video where I used them: ua-cam.com/video/29YcNXSB9KM/v-deo.html
not neccessary, there are different types of SMA edge connectors I think the footprint is designed for www.meridiancableassemblies.com/wp-content/uploads/2020/03/134569029_l-1024x680.jpg
Check the kicad stock libraries back nothing 3d or footprints shapes....tryin to find them....remember that include those libraries for sm rf coaxial connectors ..a name like: sma molex edge mounting ...tks
But you do not want 50ohm impedance in the interconnections of the filter. You want to minimize the connections in their size and length, and if length required, then to just add them to the inductor values.
I agree many circuits will have a high impedance say 3000 ohms. This filter was designed as a transmit filter between the PA and antenna to reduce harmonics. 50 ohms is required.
You have just picked the wrong footprint. I have just set out a very similar board for a 7Mhz BPF. in Kicad 6 The connector: Connector_Coaxial:SMA_Samtec_SMA-J-P-X-ST-EM1_EdgeMount In the Connector_Coax library is a very close match for the ebay SMA connectors that are like the one on you show The pads are on 2.7mm centres So I needed to tweak them to 2,54 The Molex coinnectors listed have much larger pad spacing. >4mm Andy
Nice little board! My pcb layout rule number 1 always check the footprint and data sheet, rule two alway 100% check connector pin numbering and pin location. Connectors are so easy to screw up, not all suppliers count the pins the same. Had to laugh at your escaping Metcal hand piece, that happens to me all the time. Your instinct is to try and catch it, not a good idea, dont't ask me how I know. The stand just doesn't hold the hand piece all that well, I have the holder with the ferrite core that throttles back the heat and it has the same issue. Got the same Rigol SA, have you hacked yours to 3GHz?
I *like* the logo/name in the copper! I set up a few boards with Kicad, made some silly mistakes too, it's easy to do ua-cam.com/video/CyGOf58iypY/v-deo.html I've been using a proto board from W7RLF for RF tinkering, it's quite useful, the edges are spaced nicely for SMA connectors. Can be ordered from PCBWay or I guess you could download the Gerbers and have any PCB service make it.
@@IMSAIGuy Ha! I’m guessing since you have the luxury of getting new boards made for free that you are less careful. I triple check everything. The time delay would be annoying too.
Comes naturally and easier on simple boards. The PCB suppliers need to have a selection box on the order form. Fabricate the PCB as I envisioned: Fabricate the PCB per submitted data:
I have been bitten too by wrong footprint on a board. These days if its a foot print I haven't used, I print the board to paper and wait until I have the part to test fit before ordering. As a side note, I have switched to diptrace for schematic and pcb, in my opinion so much better. they have a free version that is just as powerful and I was able to use it for about a year before I purchased a higher version
I always like to print off the Gerber’s so I can get a good idea whether I’ve got it right or not before sending them off. I can’t always get a feel for the pads on the screen, but on paper and with the parts it’s easy.
yes, I was lazy on this one. I usually print them. I always get the capacitor hole spacing incorrect the first time.
Squeak !
Love your simple pi-filter with demonstration of design, implementation, and testing. Thank you.
The SMA connector still works. But you used the Amphenol (?) footprint and not the standard chinese SMA conn footprint.
The default install for kicad has two sma connector footprints. Standard 6.3mm and Amphenol 1cm (8.5mm pin spacing). Everyone gets caught out by this!
Very cool. Wow... that iron really does heat those pads quickly!
I think KiCAD connector footprint is made to use a regular through hole connector. You can usually place it diagonally and then the footprint makes sense.
There are 3 SMA Edge Connector footprints in the standard Kicad library that cover the three main sizes, the one shown here was the first in the list and the largest. Kicad now has a measure tool in its selector so you can double check !
Emissions: “For transmitters installed after January 1, 2003, the mean power of any spurious emission from a station transmitter or external RF amplifier transmitting on a frequency below 30 MHz must be at least 43 dB below the mean power of the fundamental emission.” Sec. 97.307(d)
I like your SMA pads; better than a thin pad the iron can’t reach well.
Looks like a surface mount N connector pad area!
A KiCAD design decision was to put emphasis on a library. I never, ever use someone else's PCB library, and never one that can somehow update out from under you. Of course I don't draw all my own footprints, but if on rare occasion I use someone else's footprint I check it. I've found a personally known good library is an essential design principle. Little things that look right but aren't matter, especially with SMD footprints where surface tension plays a large part in centering the part in automated assembly.
All the footprints I end up liking, I"ve been putting copies in a separate library, so they are fast to find and already self approved.
I don't use any footprints I haven't designed myself, but I don't do any SMD work.
What do you think of stitching vias, to strongly connect both ground together ?
That may decrease the ground impedance and increase the filter performance.
for this low frequency I don't think it matters, for higher frequencies yes it is a good idea. here is a video where I used them: ua-cam.com/video/29YcNXSB9KM/v-deo.html
Thanks for the demo. That connector footprint looks like a BNC size to me. Try one just to see.
not neccessary, there are different types of SMA edge connectors I think the footprint is designed for www.meridiancableassemblies.com/wp-content/uploads/2020/03/134569029_l-1024x680.jpg
no, there are different size SMAs
I made exactly the same mistake with the SMA edge connector. There are two footprints and you chose the wrong one...
Check the kicad stock libraries back nothing 3d or footprints shapes....tryin to find them....remember that include those libraries for sm rf coaxial connectors ..a name like: sma molex edge mounting ...tks
I did exactly the same once by using a Kicad SMA footprint that didn't fit the Chinese connectors.
But you do not want 50ohm impedance in the interconnections of the filter. You want to minimize the connections in their size and length, and if length required, then to just add them to the inductor values.
I agree many circuits will have a high impedance say 3000 ohms. This filter was designed as a transmit filter between the PA and antenna to reduce harmonics. 50 ohms is required.
You have just picked the wrong footprint. I have just set out a very similar board for a 7Mhz BPF. in Kicad 6
The connector: Connector_Coaxial:SMA_Samtec_SMA-J-P-X-ST-EM1_EdgeMount
In the Connector_Coax library is a very close match for the ebay SMA connectors that are like the one on you show
The pads are on 2.7mm centres So I needed to tweak them to 2,54
The Molex coinnectors listed have much larger pad spacing. >4mm
Andy
Does the PCBWay board have the SMA footprint corrected?
no
Could you maybe to an design-guide to 50 Ohm PCBs?
I did: ua-cam.com/video/29YcNXSB9KM/v-deo.html
and this: ua-cam.com/video/QhNwoOQ15VM/v-deo.html
Nice little board! My pcb layout rule number 1 always check the footprint and data sheet, rule two alway 100% check connector pin numbering and pin location. Connectors are so easy to screw up, not all suppliers count the pins the same. Had to laugh at your escaping Metcal hand piece, that happens to me all the time. Your instinct is to try and catch it, not a good idea, dont't ask me how I know. The stand just doesn't hold the hand piece all that well, I have the holder with the ferrite core that throttles back the heat and it has the same issue. Got the same Rigol SA, have you hacked yours to 3GHz?
I remember in shop class, if you drop something, let it fall. yes the SA is 3GHz now
I *like* the logo/name in the copper!
I set up a few boards with Kicad, made some silly mistakes too, it's easy to do ua-cam.com/video/CyGOf58iypY/v-deo.html
I've been using a proto board from W7RLF for RF tinkering, it's quite useful, the edges are spaced nicely for SMA connectors.
Can be ordered from PCBWay or I guess you could download the Gerbers and have any PCB service make it.
I did a video that showed that RF board. not sure which one
Just goes to show, Free Sucks !!!
it was my mistake for using the wrong footprint, not the program
How can you make mistakes on such a simple board? 🤦🏼♂️
It's easy for me!!!
@@IMSAIGuy Ha! I’m guessing since you have the luxury of getting new boards made for free that you are less careful. I triple check everything. The time delay would be annoying too.
@@jimomertz 100% true
Comes naturally and easier on simple boards. The PCB suppliers need to have a selection box on the order form.
Fabricate the PCB as I envisioned:
Fabricate the PCB per submitted data:
@@craigs5212 That would be a great option, the 'easy' button