¿ªÔÆÌåÓýHi, there are various reasons for this. It looks as if the transmission curve has shifted upwards. That could mean that there are too few turns on the coil, or the capacitors have the wrong value. I would first check whether all the soldering points are making contact and then re-solder them. You can use an ohmmeter to check whether the coil wire is making proper contact. ? 73 Reinhard DL3AS ? Von: [email protected] [mailto:[email protected]] Im Auftrag von Sander [VK6PI] ? Hi, I recently built the QDX (for 10m - 20m) and it went really well. So far, I haven't been able to test with an antenna because of the weather, but I have used the internal test tools. ? Doing an RF sweep, I noticed that most bands are good (or acceptable for some), but the 20m doesn't seem right. ? Here are measurements for 10m and 20m: ? RF Filter Sweep at 10m ? RF Filter sweep at 20m ? As you can see, sweep doesn't look great for 20m. ? My first question is, am I measuring this correctly? I didn't want there to be any spurious transmission signal, so I hooked up a 50? dummy load. Is that necessary or shouldn't I do that? (If this is mentioned in the manual, I must have overlooked it.) ? Secondly, given the response in the second image, what could be wrong? Perhaps something wrong with the toroid (number of windings), capacitors? I'm just trying to determine how I can get to the root cause quickest. I have some measurement equipment, like DVM and oscilloscope. ? Any input would be greatly appreciated! ? 73 Sander [VK6PI] ? |
Reinhard Gr?nz