I have made a set of lp and band pass filters. Here is a 40LP. s21 (ch0) for logmag (yellow) 10dB per vertical line s11 (ch1) for swr (pink) .5dB per vertical line

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Add 50 ohm resistors across the input and output. Aug AG5AT

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I'm a little embarrassed with this project for the silly thing that I did when I assembled this thing. I ohmed the connections from the SMA to the PCB pad. I should have done it to the connector itsel

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Hi Syd, have you got your ground and rf in/outs swapped on your jig for lpfs? 73 ken g4apb

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Hey Sid, I have a (probably) dumb question. I can't really tell from the photo, but is it possible you have the filter plugged in the wrong way around? There is only one correct direction the way thes

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I'm experimenting with a few LPFs and a BPF so I put together a NanoVNA demo bd (pix) and I made an adapter bd (test-jig) to plug in some QRPLabs LPFs. On the test jig I also wired in a LPF circuit se

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Ronald, yes I used an external DVM to measure the voltage with the negative lead on the board ground and the positive lead on the pin. I will check R35 and C21. I didn't think to check R35 on the inpu

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Russ, since you see about 2.7v on IC9 pin 5, then I assume you are using an external DVM instead of the built in one. If that is the case then pins 1,2&3 readings are all very low. The bias for IC9A c

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I did a visual inspection, but I wouldn't hurt to re-flow the joints and see if it makes any difference. Thank's for the suggestion.

#calibration #filter #problem #rcvr #troubleshooting

Russ Check the solder connections around at at IC9. Since some of the voltages are good, much more likely you have a connection issue than a bad IC. I have heard of no common parts issues with the qcx

#calibration #filter #problem #rcvr #troubleshooting

I just completed a new QCX+ 20m transceiver kit. But, have run across some trouble while trying to align it. I was able to peak the band pass trimmer capacitor, but the audio level of the signal gener

#calibration #filter #problem #rcvr #troubleshooting

Correction: 100 m watts not 100ma.

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I run my U3S on WSPR 10M -80M. I got my first NanoVNA V2 and tested my filters. Found one bad, 15M. I have ordered and received an additional relay board and a full set of filters 6-160M. I am looking

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Jules, I'm at the same point. Have 4 filters done, in Diagnostic Mode waiting for the last filters and attach antenna. Maybe I'll hear yours and I hope mine gets out as far as you. We'll see. John NA3

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Thats a nice collection you got there Jules with good values. Well done.

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Just finished building several filters for the U3S and delighted with the results as tested on a VnaNano H4 (good excuse for buying one was to make sure the filters were working properly). Thanks to L

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Hi all, I also get a good IL of ~1dB when properly tuning the 40meter BPF version. I used a HP70000 series SA+TG combo for characterising; please find the plot attached. All the best, Adrian, YO6SSW

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I really hate the on line editor as it has enough lag to get old versions. (groups IO and net issue). Seems there is a lot of mixing of LPF and BPF, they are not the same thing and expected result is

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The LPPF for 20M should be 773nh for the ends and 904 for the middle. Start playing with that and you get bumps and lumps. Allison ------------------------------- Please reply on list so we can share.

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Bob, Coincidentally I constructed a QRP-Labs 20M BPF just last night. When I saw your post today, I went to work characterizing my filter. I don't have a VNA, but I do have a Siglent SA/TG here, and a

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