I tried both mods.
Not much improvements in audio quality.
I observed 59++ signals doing good with little distortion. Signals below 58 are heavily distorted.
?I have some small TDA2822 and LM 1875 amp modules in my junk. If I want use them as audio amp bypassing LM386, from where I take audio input?.
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Hello Praba,
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Two possible mods might help:
1 - Add a 10uF capacitor across C75.? If electrolytic, the + goes to pin 1. (see 9.2.2 in the datasheet)
2 - Add the bass boost circuit described in the TI LM386 datasheet section 9.2.5.
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73
Evan
AC9TU
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Re: Trying to update firmware in ubitx6.1
#v6
Issue fixed...
what i did is just made hex file from arduino IDE after compiling and the upload said hex file via Xloader.
success.?
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Makes sense. It does seem rather touchy and the effect on signal strength of the received signal is more like an on/off switch than a range, like you might expect. Anyway, it works and I am now comfortable proceeding with the bias adjustment
and band specific drive adjustment for the PA. Let me know if there is anything that I should be looking out for while I go through the process.?
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-------- Original message --------
From: "Evan Hand via groups.io" <elhandjr@...>
Date: 3/14/25 1:26 AM (GMT-05:00)
Subject: Re: [BITX20] reviving my sbitx v3
To be clear, both the receiver and the transmitter use that mixer.? It translates the signal from the 40MHz IF frequency to the operating frequency in both directions.
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73
Evan
AC9TU
-- Mike - K8MCB?
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The attached is Rx audio of my ubitx v6.1. Audio is too chirpy and unpleasant to hear. But Tx audio is good as per other hams reports. I tried several bfo adjustments. Anyone help me to rectify the issue.
Rx video clip? -
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To be clear, both the receiver and the transmitter use that mixer.? It translates the signal from the 40MHz IF frequency to the operating frequency in both directions.
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73
Evan
AC9TU
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I figured it had something to do with the reception, as when I first turned it back on and the receiver appeared to be "deaf", but yes, right around the halfway point it picked up again. I appreciate the help getting the Tx switching fixed too!
Thx and 73
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-------- Original message --------
From: "Evan Hand via groups.io" <elhandjr@...>
Date: 3/13/25 8:50 PM (GMT-05:00)
Subject: Re: [BITX20] reviving my sbitx v3
Glad you fixed it!? The other pot is used to adjust the "bias" for the mixer:
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The adjustment does not seem critical.? I would set it to the midpoint and verify that the receiver is sensitive and that the transmitted CW signal does not have spurs.
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73
Evan
AC9TU
-- Mike - K8MCB?
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Glad you fixed it!? The other pot is used to adjust the "bias" for the mixer:
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The adjustment does not seem critical.? I would set it to the midpoint and verify that the receiver is sensitive and that the transmitted CW signal does not have spurs.
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73
Evan
AC9TU
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Evan, I finally got it going! My problem was having more than one problem at a time. Once I replaced everything in the circuit, fixed dry or bridged joints, and put a new set of finals in, it now switches and has output. However, before I even
touch the bias pot, does the other pot have anything to do with this circuit? It doesn't appear to, but I mistakenly put it to full ccw with the bias pot too. What is the pot for and how should I set it?
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-------- Original message --------
From: "Evan Hand via groups.io" <elhandjr@...>
Date: 3/10/25 10:10 PM (GMT-05:00)
Subject: Re: [BITX20] reviving my sbitx v3
Michael,
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The first step is to verify that the Q10 Drain goes to zero when TX goes to 3 volts (or higher).? If that happens, Q10 is OK.? If not, it is bad.
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Once Q10 works, verify that the Q9 tab (Drain) goes to 12 volts when the TX signal drives the Q10 drain low.? If that does not happen, remove Q9 and check the operation of Q101.? Do this with Q9 removed to prevent damaging both devices again.
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Q101 drain goes to zero when TX and Q10 are off.? When TX is low, the Q101 gate should go above 5 volts to make Q101 turn on.? When Q10 turns on with the TX signal, Q101 should turn off.? If Q9 is removed, you can verify that the Drain-to-source resistance
is very high with an Ohm meter.? Q101 Drain to Source resistance should be close to zero when TX and Q10 are on.
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An alternative approach is to remove Q101 so there is no short on the 12V line during receive, Verify and replace bad parts, and then install a verified working Q101.? I built a test jig on a small copper-clad board with wires to insert into a component
tester.? I hold the device with tweezers to connect each lead to a separate pad.
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73
Evan
AC9TU
-- Mike - K8MCB?
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Re: uBITX v6 Low Audio - Back at it again - FIXED
Glad you fixed it and that I could be of help.?
73
Evan
AC9TU
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Re: uBITX v6 Low Audio - Back at it again - FIXED
Hello all, and thank you for helping me getting my uBITX V6 up and running again. I replaced C30 this morning and I now have audio. Next will be alignment, BFO, and the frequency display is off. So I'll tackle that soon and if I run into problems I'll start a new thread. Thanks again to all and Evan for sending me some new parts. You guys are the greatest. 73, Richard AG5M
On Friday, February 28, 2025 at 02:53:06 PM PST, Richard AG5M via groups.io <ag5m@...> wrote:
Unknown. I heated the end closer to the back of the PCB, and the cap fell right off the board, with a end still on the PCB. A check of the cap shows it is open, not surprising with the end missing.
Anyway, I found a 0.1uF cap in the junk box, just a tad too big, Hi Hi, to put in on the board, but connecting it to the board gives me LOTS of audio again. When replaced with an appropriate cap I'll be back in business. Then to calibrate the BFO, frequency, etc. And have it on the air again.
73, Richard AG5M
On Friday, February 28, 2025 at 02:25:59 PM PST, tomekdm sp7etd via groups.io <tomekdm@...> wrote:
Interesting why it cracked/failed... due to mechanical stress, like bent of PCB... temperature shock...? or was it already bad since new...
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I built a new trx ...12m DSB ft8.
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It is a simple TRX using one TA7358 and 7 x 2N2222 ... 800mW .
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73 de py2ohh miguel
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Re: RX uBITXv5 from scratch
Looks nice. Congratulations!
73s John N4HNO
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Re: RX uBITXv5 from scratch
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Hello everyone, I realize I'm late to the topic, but after a course by the ARI Parma association on the uBITX V5, I wanted to try my hand at designing a single-sided PCB for the receiver part only using Kicad and TH components.
I actually created two versions, the first educational, with well-spaced components and the second more compact and more suitable for being placed in a container. Both involve the use of Raduino and the low frequency part, separately. I also created the PCB for these two modules.
I'll make them available in case anyone wants to create the RX part only and suggestions are welcome.
Soon, I hope to be able to create the TX part too.
Thank you and 73 de IU7SUX
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/g/BITX20/files/IU7SUX
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Re: sBitx Mic input - assist request
I got this element and stuffed cotton balls in the housing and get GREAT audio reports?
PUI Audio, Inc. AOM-5024L-HD-R
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Re: sBitx Mic input - assist request
Was there a mic input modification for the sBtx DE because I am getting reports of bad or distorted audio.
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The mic element I am using was the one that came in the uBitx v3 kit.
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Was thinking of giving a Heil headset mic with the IC element in it a try. Just have to make a adapter cable for the PTT part and not short the mic.
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Do you guys think thats a good idea?
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Re: sBitx v3 - problem with nonstandard callsigns
I have cloned and added my suffixed callsigns to the test: OE/SP5DAA, DE/SP5DAA, SP5DAA/2, SP5DAA/P (in ft8_lib/test/test.c)
Only SP5DAA/P is encoded and decoded correctly. Three others fail.
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Below is one of the test cases:
Encoded [YL3JG] [DE/SP5DAA] [KO26]
Decoded [YL3JG] [<DE/SP5DAA>] [KO26]
FAIL: Condition '0 == strcmp(call_de, call_de_tx)' failed!
Encoded [YL3JG] [OE/SP5DAA] [KO26]
Decoded [YL3JG] [<OE/SP5DAA>] [KO26]
FAIL: Condition '0 == strcmp(call_de, call_de_tx)' failed!
Encoded [YL3JG] [SP5DAA/P] [KO26]
Decoded [YL3JG] [SP5DAA/P] [KO26]
Test OK
Encoded [YL3JG] [SP5DAA/2] [KO26]
Decoded [YL3JG] [<SP5DAA/2>] [KO26]
FAIL: Condition '0 == strcmp(call_de, call_de_tx)' failed!
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Another case:
Encoded [DE/SP5DAA] [YL3JG] [KO26]
Decoded [<DE/SP5DAA>] [YL3JG] [KO26]
FAIL: Condition '0 == strcmp(call_to, call_to_tx)' failed!
Encoded [DE/SP5DAA] [W1A] [KO26]
Decoded [<DE/SP5DAA>] [W1A] [KO26]
FAIL: Condition '0 == strcmp(call_to, call_to_tx)' failed!
Encoded [DE/SP5DAA] [W1A/R] [KO26]
Decoded [<DE/SP5DAA>] [W1A/R] [KO26]
FAIL: Condition '0 == strcmp(call_to, call_to_tx)' failed!
Encoded [DE/SP5DAA] [W5AB] [KO26]
So it seems that this fix still does not remove the problem, especially for those travelling abroad.
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73,
Wojtek
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I agree with most of Ken and Lee's points.? What is not mentioned is the enormous amount of software that Ashhar Farhan used that is open source and may not be available for the "lower cost/higher performance" options.? Also, note that the sbitx and zbitx can run digital modes without adding a computer.? Most of that is possible because of the Linux base that the Raspberry Pi uses in most of its forms.? That could also go away if another processor is selected.
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If the specs published for the zBitx are met, the closest competitor is the QMX+ from QRP-Labs.? The QMX line needs an external computer for most digital modes.? The QMX does include two more bands (160 and 6 meters) than the zBitx.? The QMX does not have a graphic touchscreen interface.? The QMX firmware is proprietary and not modifiable by the user.? The advantage of open-source SW is best exemplified by the 64-bit dev team (led by JJ W9JES) 's work.? That software is a HUGE improvement over the original get-to-market version distributed by HFSignals.? Both the zBitx and QMX+ cost the same with a case: $150.? Both specify 5 watts, with SDR-based digital filters for signal processing.? I will own both when my zBitx arrives.
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I am one of the original 250 "lucky" users.? I am anxiously awaiting my shipment notice and receipt of the radio.
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All good things take time.? Speculating on shortcomings before analyzing the product is wasted time and effort.
73
Evan
AC9TU
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Richard AG5M
IU7SUX Antonio