On Fri, Dec 6, 2024 at 12:02 PM, Jerry Gaffke wrote:
These boards are factory stuffed with no-lead solder, so you need some really hot soldering irons to melt it.
Thanks for your discussion of the VNA approach, Jerry!
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When I had to replace my SOIC gates after the finals in my QMX+ blew after experimenting with EEPROM settings in an ATU, I could not get the solder to melt with hot air until I was already far too fearful for the health of the PCB and nearby components, despite first masking surrounding areas with both 3M insulating fiberglass tape covered by 3M stainless steel tape. The technique I developed, which I've since learned is similar to the Chip Quik SMD rework kit, is I first used solder wick and an iron to remove as much of the difficult-to melt Pb-free solder as possible. Then I added some good 'ol regular lead/tin solder to the SOIC legs and more flux too. After "re-alloying" the joints, they melted quickly with hot air and I picked off the SOIC using tweezers like a dream! Nearby components and the board were unaffected.
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73,
Cal (AD8Q)
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On Fri, Dec 6, 2024 at 10:43 AM, Cal (AD8Q) wrote:
I just checked and I have that "bench" on 40m too. I do have better than -20dB at the 2nd harmonic frequency though (attached screenshot), which is the worst attenuation of all my LPFs/bands. Others are about -27dB at the 2nd harmonic or a little better.
