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bitx20 problems
I have been a radio amateur since 2007.
over the years I have made many contacts worldwide? using comercile radios like ts-450 and ic-703. nevertheless, I always thought that was a bit of cheating, a shared honor with icom and kenwood.
there is a lot to be found on the internet concerning homemade transceivers.
on some websites you see diagrams, explanations, photos.
sometimes it all looks so simple. like you just build the simple circuit and you're done. But that is not my experience. sometimes I think it's a bad design or I'm just a stupid builder
in 2012 i started building the bitx20. clean with a printed circuit board that I had made.
it was many years and failed project, But now I? want to make an attempt to finish it
the receiver works, but not completely clean. I hear many mixing frequency products.
the recipient was deaf. in ssb they were only very strong stations. who came through it.
the transmitter: almost no carrier suppression
the pre hf amplifier (q14) functions as an attenuator.
i am not sure regarding the rf transformers. TV balun core is a vague description. Can it also function well with a ft37-43?
i also built the hf amplifier with? 6?? 2n2018 transistors.
i used an hf oscilator (ne602 with a bit of external gain) to test the hf amplifier.
there was power gain, I had 250mW not the expected 5W
it is not specified which diode it must be.
I managed to get a 1N4001 in it I hope you can give some advice in the hope of resolving technical issues. |
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Re: ubitx s-meter swr-meter help
#bitx20
#bitx40
#bitx40help
#arduino
#calibration
Adrian,
check out kd8cec video on his swr meter that connects to his standalone signal processor. I think that is the functionality you are trying to achieve? ? The Nextion to sketch code is a little complex (basically kd8cec fills a buffer with commands and data and sends them to the nextion to do the work.) In the two nano configuration, both nanos are talking to the nextion which does the display at request of either nano. So you will want to look at the sketch in the ¡°standalone signal processor¡± not the sketch that is currently running on your ubitx at the moment. Perhaps you can lift some code there.? You might also want to checkout how much memory you have left on the sketch you are currently running in you ubitx. I suspect that kd8cec went to the two nano configuration because he was running at of cpu power and memory. Sorry I can¡¯t be of more direct help here! 73 Mark AJ6CU |
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Re: Antuino support group opened -- early antuino question
I agree.
toggle quoted message
Show quoted text
The nanoVNA cannot do all of the many things an Antuino can do, and vice versa.? Nor does either one replace an inline SWR meter. That said, the nanoVNA looks like a very nice addition to the toolbox. Jerry On Fri, Aug 16, 2019 at 02:07 AM, Gerry Kavanagh wrote: Different use case, IMO. I have a NanoVNA, and it's great for measuring passive devices' S11 & S21 parameters, but for signal measurement (spectral purity, power level) it is useless. This is why I ordered the Antuino. |
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Re: VOX Issues to be aware of. Or, suspected new digital mode.
Tom,
lol Snoring as a digital mode! I wonder if your brain in encoding some diagnostic information on the snore? Research funding? I wonder if the voiced/unvoiced decision could be ripped from CODEC2? Maybe for a syllabic squelch for an hf receiver but probably too slow for a Vox on tx. bob wm6h ? |
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VOX Issues to be aware of. Or, suspected new digital mode.
Hi,
I don't if many people have added VOX to their uBitx, but here is a reason to be careful. Maybe a DSP VOX controller could be built to guard against accidental digital mode emissions. Kind of like the computer keyboard filters that were supposed to detect and reject keystroke when your cat walks across your keyboard. Wonder how well the narrow CW filters would work with this mode interfering. Here is a video of a HAM trying to determine what this new digital mode is.? https://youtu.be/TJSctUv5lUc?t=274 Tom, wb6b |
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Re: Narrow filter for CW
#ubitxcw
Oh sorry, forgot to mention.
This is not an audio filter, but a second crystal filter chain on 4MHz while the CW wide and SSB filter is at 12MHz. Alex |
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Re: Narrow filter for CW
#ubitxcw
Hi all,
Jerry mentioned my efforts for a second filter for CW. Just to have an indication how it performs here is a link to a short youtube film I am very happy with the result. 73, Alex PA1FOX |
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Re: Carrier suppression on uBITX v5 - -35 to -40 dB ok?
Rob,
To answer your question, -35-40 is what I have measured using an SDR Play RSP2 and the spectrum analyzer software (this is the only tool? that I currently have that can get a low enough resolution band width RBW to make the measurements). I did use a two tone generator on the mic input to verify the audio vs carrier.? Simple matter of turning on and off the tones while keeping the uBitx in transmit mode. There are two possible causes for carrier leakage that I have fund: 1 - mixer diode issues as you have pointed out 2 - BFO out of alignment I found that by changing the BFO setting I will get some carrier injected back into the signal, even if the mixer is OK. I tested the mixer diodes by injecting an ac signal into the BFO transformer across the output coil coming from the BFO to the mixer and measuring the common connection of the mixer diodes with an oscilloscope to verify a half wave looking signal.? If they were bad, should not get a full wave rectified waver form.?Not sure if it is the best way to verify the mixer diodes, however seemed to work for me. NOTE: in doing the transmit test I first established the power level at frequency using CW and an SWR/POWER meter in the line between the rig and the dummy load.? I then adjusted the tone generator output to be at the same or slightly lower level, and that the distortion on the measured spectrum was minimal.? As Ashhar stated, there are audio programs or recorded wave files that can provide the constant 2 tone audio.? There are also good kits that can provide a very pure tone/tones. Also of Note: I am not at my QTH so cannot get to the actual rig and verify the connection points for the mixer diode verification test. FWIW 73 Evan AC9TU |
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I have 4 uBITX radios and the first one had stuck the left side relay early on. I replaced it with a stock component and it has worked fine. None of the other machines has had a problem. This relay only carries signals on the receive side so no chance of spurious emissions.
Good luck with your repair. I approach repairs from the viewpoint of a repair technician rather than that of an engineer. I always get a chuckle with those who think they need a wall full of test equipment to fix these critters So far I have been able to resurrect all 3 uBITX radios determined to be junk by previous owners. 73 all Dave |
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Re: Carrier suppression on uBITX v5 - -35 to -40 dB ok?
Gordon Gibby
¿ªÔÆÌåÓý?A significant number of sound interface systems will have a TRANSFORMER here and there.? ?It is important in most cases to provide DC isolation to prevent the transformer from dramatically changing the biasing conditions of the mic input amplifier of the
radio to which it is connecgted.? ?This blindsided me once when I connected a homebrew isolator (with transformers) to an icom 2 meter rig to do packet -- and the signals sounded horrible.? ?You won't damage the transformer, but you can throw the linearity
of the mic-amp stage out the window.? ?A Signalink in the same situation did FINE -- because it had capacitor dc-isolation.? ?I learned the hard way to DC isolate.
Cheers, Gordon
From: [email protected] <[email protected]> on behalf of Tom, wb6b <wb6b@...>
Sent: Saturday, August 17, 2019 4:04 AM To: [email protected] Subject: Re: [BITX20] Carrier suppression on uBITX v5 - -35 to -40 dB ok? ?
Hi,
I just double checked the schematic. It looks like there is adequate DC blocking capacitors in the mike input circuit. Also, the mike input already has a DC voltage applied to power the microphone. So, unless the sound card doesn't like the DC voltages and causes distortion, it is likely not the source of the carrier leakage. I'm not sure how much is good or bad, but the topic of carrier suppression and fixes has come up on this group. Hopefully, other may be able to shed more light on what level is acceptable. I have had good success with connecting the high side of the volume control directly to the microphone input of a USB sound dongle. And the headphone output of the USB sound dongle directly to the microphone input of the uBitx. Some sound adaptors may work better or worse in this configuration, but the generic adaptor used seems fine in this arrangement. It is possible some sound adaptors might not like the DC voltage (but low current) the uBitx puts on the microphone input applied to the headphone output. Tom, wb6b |
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Re: Carrier suppression on uBITX v5 - -35 to -40 dB ok?
The carrier to signal ratio needs to define the signal level as well. A 'Haaalllowww' is usually insufficient (though I use it all the time). You could download a wav file of two tone and play that into the mic. That is the simpler way to do it properly. - f On Sat 17 Aug, 2019, 1:34 PM Tom, wb6b, <wb6b@...> wrote: Hi, |
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Re: Carrier suppression on uBITX v5 - -35 to -40 dB ok?
Hi,
I just double checked the schematic. It looks like there is adequate DC blocking capacitors in the mike input circuit. Also, the mike input already has a DC voltage applied to power the microphone. So, unless the sound card doesn't like the DC voltages and causes distortion, it is likely not the source of the carrier leakage. I'm not sure how much is good or bad, but the topic of carrier suppression and fixes has come up on this group. Hopefully, other may be able to shed more light on what level is acceptable. I have had good success with connecting the high side of the volume control directly to the microphone input of a USB sound dongle. And the headphone output of the USB sound dongle directly to the microphone input of the uBitx. Some sound adaptors may work better or worse in this configuration, but the generic adaptor used seems fine in this arrangement. It is possible some sound adaptors might not like the DC voltage (but low current) the uBitx puts on the microphone input applied to the headphone output. Tom, wb6b |
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Re: Calibration success
#ubitx
#calibration
Thank you Leonard. This particular mic doesn¡¯t have a preamp....so no chance of over driving.
Dean |
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ubitx s-meter swr-meter help
#bitx20
#bitx40
#bitx40help
#arduino
#calibration
Hello i am using the 1.80 firmware from KD8CEC?on my ubitx with a 2X16 lcd display? and i have noticed the s-meter bargraph? is working only in Rx mode, but when i switch to TX gets stuck with the last value . I want to use the bargraph while transmit to measure the power or the swr. i think? the display update is disabled while tx in the source code. any help wil be appreciated, thanks in advance 73! YO4HUJ Adrian.
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Re: Narrow filter for CW
#ubitxcw
Regarding a CW filter , a simple audio filter with 2 or 3 Amps from a Quad-opamp might be a simple start for good CW listening. There are many circuits on the Web.
Frank??? ,??? EI7KS |
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Re: Narrow filter for CW
#ubitxcw
My reply is for limited use at audio level. Sorry. May not be relavent.? On Fri, 16 Aug 2019, 9:11 pm Mvs Sarma, <mvssarma@...> wrote:
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Re: Narrow filter for CW
#ubitxcw
Why not use max7400 as a n lpf. It is a nice 8 pin dip and/or sm? Spend a while to study the datasheet. It can become variable lpf. On Fri, 16 Aug 2019, 4:38 pm _Dave_ K0MBT, <davesters@...> wrote: Yes I was hoping to steal someones design and spend less than 10 dollars. |
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Re: Narrow filter for CW
#ubitxcw
For those who don't get the joke... On Fri, Aug 16, 2019 at 8:48 AM Gordon Gibby <ggibby@...> wrote:
Dale Hardin 24750 State St. Unit 487 Elberta, AL 36530 251-597-9256 --
Dale Hardin, KS4NS Elberta, AL |
_Dave_ AD0B
Dale Hardin KS4NS
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