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Warren: The fifth and the 7th are at -45dB now. You are missing my point. The design of the filter directly effects the level of the harmonics. Yes, the stray? capacitance creates a "sneak" path

First there are two issues one being poor harmonic filtering and Kees is addressing that here. The other is spurs from inadequate filtering above 17M,? That requires band pass filters before the

Kees: Why manual band switching? Could not the code select the proper filter according to frequency the user selects on the uBitx? Could not the RF Switching be done using pin diodes or FET switching?

Howard When I measured 80 meter harmonics the particularly troublesome ones were 5th at 18 MHz and 7th at 25 MHz. In both cases the attenuation of the stock uBitx at those frequencies was limited by

Kees & Group: Please Clarify: I thought I was told some time ago on this post that only passband filters would address the uBitix issues. If that earlier statement was correct, why are people working

I previously mentioned that I would try to reduce the harmonics by changing the output to 25 ohms and adding a step up transformer to go back to 50 ohms for the output. This would allow tripling the

An alternate improvement is replace Q10/11/12 with mmbt2369 or BFr106 as the 3904 is not impressive at 45mhz. Allison

Henning, There are errors in the diagram and the levels are really different than shown. Looked at your diagram and its assumptions are wrong.? If the final mixer can accept -1dbm without producing

Lawrence G., I tried a few things along that path.? made matters worse and that was also tried with external level 7 mixer and level 17 external mixers.? ?It was then a rock fell on me and I

That’s funny! Best little joke today!! Even a novice in my day knew that kind of stuff. Oh how times change !!

MRM, The not so funny part Is I've been saying that for over two years and especially the last two months. The whole idea of minimally filter 3-30 mhz radio is wishful thinking.? When I first said

I solved the root cause, an open wire. But, now the Arduino does strange things, it locks up, sometimes I get very distorted CW xmit waveforms. The mystery continues.

There is also the outstanding, yet related, issue with switching sidebands on CW (i.e. CWU to CWL or vice versa) with KD8CEC's code which I had? previously documented.? Try this on any commercial

Gordon. we have people with their extra that can't figure out how to connect the key to their radio (not just bitx radios, commercial too). How do you figure they're able to detect their band edges on

Hello Allard, I am a CW-only ham, so your 1.27.7 sketch made me love the BITX40. Today I tried to upload the 1.28 upgrade but, surprisingly, it does not sense the key and transmit CW any more.

Gordon and all, His software is on our group website in the "Files" section. Jim, W0EB http://www.w0eb.com we do not use github

Ron Where do I go to look for your group software? Now that I got my harmonic somewhat more under control, I’m going to want to pick out good software modify it if needed and have it ready for our

Sort of… I added a second receiver to my uBITx on VFO B. It’s great for DXing. I, like you, do like the uBITx receiver. You can even do some clever things with the audio (stereo channels one for

Dear members you can check: 1. Add parallel to R12 C=470 pF: in my analiser I could see 3 dB gain rising on 30 MHz, 0805 smd resistor over R12; 2. Added two 100 Ohm? to collectotrs Q11 and Q12 (had

W.r.t the current discussions on ubitx transmitter woes ... the route forward that I chose was to order LPFs plus the relay board from QRP Labs. My thoughts were to use a 2nd Arduino Nano clone