Ah, I see that Farhan responded, you're in good hands.
The only problem I see is that he will tell you how easy it is.
Which for him, it is, as he has debugged plenty of these radios.

He might even enjoy dredging up a few dim memories from his distant youth:
??

(Having written that, did a quick check and found your post of the schematic.
Exactly the one from the webpage above, created some 25 years ago.)??

Jerry

开云体育

That's a very long list of trouble.
And? a rather old Bitx design.
Most folks in this forum are now using either the Bitx40 or the uBitx from hfsignals.com.

Radio circuits are seldom simple to get working well, especially if you don't have
a couple thousand dollars worth of test gear and 40 years experience with it.
And sometimes, even when you do.
Even for stuff considerably more simple than your Bitx20.
A complete superhet SSB transceiver is definitely not simple,
though the Bitx design is getting close to being as simple as possible.

I suggest you get a $59 Bitx40 working, that might prove challenging enough:
???

If you really want to get this older Bitx20 working, you need to tell us which set of?
instructions you are working from, what you did different, where you had questions,
post a few photos, describe the test gear you have at hand, and a full description
of each problem as you take them one at a time.? Assume months, given your
initial description. And likely involve at least having a DVM and a 10mhz scope
(preferably better) and something like the Antuino available to help debug it.
Just getting the crystal filter to behave properly and the VFO stable enough
may prove to be significant "learning opportunities".

Jerry, KE7ER? ? Flora OR

Knowing that I might open a can of worms, here I go:

I have been monitoring this group for almost a year now, and have not seen any information posted on the original BITX20 during that time.? I also did a search on the files section and could not find information there, except on how to modify a BITX20 3 series to be multi band. Granted that I used BITX20 for the filter, and there may be a better choice.? Even the history document is not clear on what the early designs were for the BITX series.? I would assume that the design that you built is VFO controlled, rather than Si5351 based similar to the original BITX40 that later was modified to include the Raduino with Si5351.

There hopefully are others on the feed that did work with the original BITX20 that might make sense of your questions.? For me, I would need the schematics at least.? I would suggest that you point us to the information that you have on that original design so that we could make suggestions.

Alternatively, wait and hope someone that worked on the version that you built can chime in.


73 and hope someone can help you.
Evan
AC9TU

Yes, with 16v to the finals I get a few more watts. At 80m with 16V and 25w there is 1.6 amps running around -- and maybe more with spikes here and there?

I've asked multiple folks on 80m (where I get the most watts) if they see any artifacts in my PSK signal (for example), and I get fine reports. I have seen wickedly over driven PSK signals with echos on the right and left of the PSK railroad tracks -- and I never want to send that out!!

I confess when I got my uBITX I was clueless oh how to monitor, adjust, and control my drive levels.? In the early days I'm sure I sent out a bunch of majorly over driven stuff. i'd like to go back in time and apologize to anyone who saw the mess I was sending, hahaha.? But, all I could say was...I'm sooo sorry I'm just learning how to figure out all this stuff.? And even the volume control took a while to understand. hahaha.

Don
km4udx

Tom+++

I built an little Easy digi interface kit with small transformers, DC blocking cap, to bridge the ubix audio i/o to the laptop audio i/o.? Then I realized by laptop audio i/o jacks were all broke, so I had to use a cheap external usb sound card just to gain good audio i/o jacks from the laptop. Going from uBITX audio i/o to EasyDigi i/o to cheap usb sound card dongle i/o to laptop usb port all worked 100% fine.

But.

Is the EasyDigi interface totally redundant given that I have to use a external sound card anyway?? I don't need the audio transformers for isolation -- the external sound card does that function, and nothing is bothered by the mic+v so? I don't need the blocking DC cap either.? Can I remove the EasyDigi from the audio i/o chain and go straight from uBITX audio i/o to sound card i/o??

Thanks oh wise ones for the insight and guidance!

Don

Symptom: uBITX doesn't recognize the straight key. Electrically, the CW key line checks OK.
Solution: Go to settings->CW->Hand key[Select]

in 2012 i started building the bitx20. clean with a printed circuit board that I had made.

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

I agree.
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

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
?

On Sat, Aug 17, 2019 at 07:47 PM, Tom, wb6b wrote:

https://youtu.be/TJSctUv5lUc?t=274

Th link did not get linked. Here is the linked link.

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

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

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

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

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

开云体育

?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