I had a similar experience, but the problem was not with the radio. It was a poor solder joint at the antenna.
Once I would transmit the problem would go away then start to fade until I would key the transmitter. I could run a few watts of power to have it clear up. Drove me nuts for a while.
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Barry
K3BO
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Last night I was thinking about it and I believe the first thing I'll try is cold spray. A bad solder joint could be the problem and cold spray sometimes reveals those.
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Possible bad relay noted... But the gradual fading doesn't very seem consistent with a bad relay. In my experience those are more on and off type failures.
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I am fairly sure that this is a real loss of sensitivity rather than an audio problem, but I can determine that easily once it's on the bench.
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Thanks for all the suggestions, and I'll let you know how it works out.
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You really have to scratch up these old memories. the same thing applies to the contacts for the Vibroplex Bug Brown Paper worked best as t was a little more coarse. Change out the relay take the old one to the bench, dismantle and clean the contacts check the tension, and set aside for the next occurrence.
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Aha, before shortening/bypassing You can try open the radio and delicate knock K3 and K1 relays with screwdriver or similar tool. Sometimes phenomena/failure reacts on this - then You can be 99% sure - this is a relay. Another thing might be some cold soldering point.
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the traditional way to clean relay contacts depends on being able to carefully pry the plastic case off.? ?Usually this can be accomplished.? May require small "jeweler' " screwdrivers.
Then take a narrow strip of paper and draw it between closed (gentle pressure) contacts.? A smudge of BLACK at the beginning is proof of dirty contacts. I have been amazed at the ability of dirty contacts to disrupt signals.? ?This was the bane of vacuum tube transceivers back in the day.? ?For this reason, the higher priced units had SOCKETS for those relays, so you could change them more easily
Gordon KX4Z
On Sun, Oct 20, 2024 at 8:11?AM tomekdm sp7etd via <tomekdm= [email protected]> wrote: ?Hello,
I will not write too much more than previous colleagues - I also would start checking relays. Yes, relays. RX path goes through TWO relays K3 and K1 (type HFD27/012-S relay).?
By default RX path is shorted with pins 11-13 of K3, but also M1-M2 points just before audio amplifier are shorted during RX with K3 4-6 pins.
K1 relay shorts RX path through pins 4 and 6, but also powers RX or TX sections through second pair of contacts. So there are a lot of relay contacts which are influencing correct TRX operation. Not only passing radio signal through, but also powering of RX/TX sections. So in first place correct relays operation must be confirmed before we will go further. Contacts view from the bottom:
?  ?
I would start from bypassing (shortening) of pins 13-11 and 4-6 of both relays (K3 and K1) and would check for correct RX operation - all middle pins of K3 and K1.
!!!BUT be aware not to perform transmit during bypass because You will BRICK the radio! Replacing relay is difficult and needs good preparation/strategy.
It is large component with 8 legs - it is difficult to heat all them together and not break the PCB traces - via holes. Someone will use hot air, someone two irons and big drop of tin to heat up all legs simultaneously and carefully lift relay. Second person help may be also useful. Do no hurry. Another way is to carefully destroy/break the relay and try remove carefully leg one by one. Most important not to destroy the PCB/delicate via holes. So as You see replacing relay might be a challenge - so first make sure one of them is a root cause. If You will decide to swap - You can watch for better quality ones. I think OMRON G5V-2 12VDC is also a replacement. They are widely available. Or am I wrong? Good luck. Give us feedback. Regards. Tomasz
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?Hello,
I will not write too much more than previous colleagues - I also would start checking relays. Yes, relays. RX path goes through TWO relays K3 and K1 (type HFD27/012-S relay).?
By default RX path is shorted with pins 11-13 of K3, but also M1-M2 points just before audio amplifier are shorted during RX with K3 4-6 pins.
K1 relay shorts RX path through pins 4 and 6, but also powers RX or TX sections through second pair of contacts. So there are a lot of relay contacts which are influencing correct TRX operation. Not only passing radio signal through, but also powering of RX/TX sections. So in first place correct relays operation must be confirmed before we will go further. Contacts view from the bottom:
?  ?
I would start from bypassing (shortening) of pins 13-11 and 4-6 of both relays (K3 and K1) and would check for correct RX operation - all middle pins of K3 and K1.
!!!BUT be aware not to perform transmit during bypass because You will BRICK the radio! Replacing relay is difficult and needs good preparation/strategy.
It is large component with 8 legs - it is difficult to heat all them together and not break the PCB traces - via holes. Someone will use hot air, someone two irons and big drop of tin to heat up all legs simultaneously and carefully lift relay. Second person help may be also useful. Do no hurry. Another way is to carefully destroy/break the relay and try remove carefully leg one by one. Most important not to destroy the PCB/delicate via holes. So as You see replacing relay might be a challenge - so first make sure one of them is a root cause. If You will decide to swap - You can watch for better quality ones. I think OMRON G5V-2 12VDC is also a replacement. They are widely available. Or am I wrong? Good luck. Give us feedback. Regards. Tomasz
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A dirty relay was my first thought, but the fading doesn't seem consistent with that. I'm just getting started with the problem.
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I have a fairly complete test equipment suite. Once I get inside I'll probably just try signal tracing. But it's intermittent, and the way things go for me typically I'll take it apart and the problem will go away.
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Re: Hendricks BITX20 C18 Procrastinator Question
JP
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Let's try what you have. Often the receive preselected is forgiving. Don't initially solder it flush, maybe on a couple leads. If your jukebox part doesn't have enough capacitance, put a small fixed capacitor in parallel with it
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Curt
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Here is a copy and paste of my logbook on what I have done so far:
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Upgrade the operating software for sBITX-V3 / 581EFC18613 From sBITX-3.021 to sBITX-V4
Starting with fresh SanDisk Ultra 128 GB microSDXC UHS-I Card
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Backup sBITX.db and hw_settings.ini files: Open up the sBITX file system and go to the following file location: /home/pi/sbitx/data and I copied the following files to USB Thumbdrive:
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create_db.sql
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default_hw_settings
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default_settings
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display_log
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ft8.mc
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hw_settings
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hw_settings_v2
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hw_settings_v3
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result_rows
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sbitx
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user_settings
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Download the sBITX 64BIT operating software from the following link:
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Upon going to the above link another page appears with the following message:
Google Drive can¡¯t scan this file for viruses.
Sb64p2.img.xz (2.2G) is too large for Google to scan for viruses. Would you still like to download this file anyway? I clicked yes and downloaded the file to the following location: C:\Users\K5ATG\Downloads
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Opened up Raspberry Pi Imager v1.8.5 and performed the following actions:
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Raspberry Pi Device: Raspberry Pi 4
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Operating System: Use Custom: C:\Users\K5ATG\Downloads and selected the following file: Sb64p2.img.xz
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Storage: Generic STORAGE DEVICE USB Device ¨C 127.9 GB Mounted as G:\
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Clicked: NEXT
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A window popped up: Would you like to apply OS customization settings? Edit Settings
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OS Customization Window Appeared the following settings we applied (Under General Tab):
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Click: SAVE
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A window popped up: Would you like to apply OS customization settings? YES
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A window popped up: All existing data on ¡®Generic STORAGE DEVICE USB Device¡¯ will be erased. Are you sure you want to continue? YES
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At this time the Raspberry Pi Imager v1.8.5 will start burning the file Sb64p2.img.xz to Generic STORAGE DEVICE USB Device
I rebooted the sBITX/RPI and this is where my path has taken me so far. In the Ham Radio menu the sBITX and sBITX Apps icons are both blank.? When I click on the sBITX Icon a pop up window appears that says: Invalid desktop entry file. '/usr/share/applications/sBits.desktop'
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Personal Note:?When I reboot the sBITX/RPI the 64bit sBITX logo appears as the system is starting up. I'm guessing here but I think that I have the 64bit OS installed but not the sBITX software itself.?
--
'72
Aaron?
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Could be dirty contacts on a t/r relay.?
toggle quoted message
Show quoted text
On Oct 19, 2024, at 14:15, DaveW, KL7HJF via groups.io <david@...> wrote:
? Also, are you using stock firmware or something else?
What aftermarket modifications have been done? (such as an added AGC or AVC circuit)
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Check the transmit/receive relay On Sat, Oct 19, 2024 at 7:31?PM Demonmariner via <Propinquityslo= [email protected]> wrote:
I have a uBitX V6 that I've been using off and on for a couple years that has recently shown a tendency to intermittently fade its receive sensitivity. Triggering transmit (usually ) immediately brings the sensitivity back up, and after a few minutes it fades again.
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Can anyone point me to someplace to begin troubleshooting the problem? Thanks
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Also, are you using stock firmware or something else?
What aftermarket modifications have been done? (such as an added AGC or AVC circuit)
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I wonder... is the issue receiver sensitivity or audio volume?
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What test equipment do you have available? (AC/DC voltmeter, oscilloscope, etc.)
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I have a uBitX V6 that I've been using off and on for a couple years that has recently shown a tendency to intermittently fade its receive sensitivity. Triggering transmit (usually ) immediately brings the sensitivity back up, and after a few minutes it fades again.
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Can anyone point me to someplace to begin troubleshooting the problem? Thanks
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Can you test that the wm8731 works? Just open the browser and play something from youtube.
Hi Dean,?
I had a faulty si5351, and the screen shows up, it's frustrating when a software you never used does not work. I have a I2Cbb fault that could be the Attiny that is not yet wired. And it says unable to load init file now I go on with a bit mechanics to get it stable.
Thank you and best 73s
Hubert F6duk?
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I have this for my uBITX and have gotten good results from it over the stock mic. I'm wondering if it would work for the sBITX also
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--
'72
Aaron?
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Re: Components sourcing Europe
Hi!
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Im really not "that" guy, but just go eBay and filter for Europe, it never let me down.
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J.
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Homebrewer and sleep provider (anestetist)
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Hi Dean,?
I had a faulty si5351, and the screen shows up, it's frustrating when a software you never used does not work. I have a I2Cbb fault that could be the Attiny that is not yet wired. And it says unable to load init file now I go on with a bit mechanics to get it stable.
Thank you and best 73s
Hubert F6duk?
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Aaron,
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Here's what I used with success but it was V3. For subsequent versions I used the ./update option.
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Release sBitx 64 bit v3.02 RC1 ¡¤ drexjj_sbitx ¡¤ GitHub.pdf for guidance
balenaEtcher-1.5.109-x64.AppImage running on Ubuntu 20.04
sb64b2.img.xz as the image file
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73, Bruce, W4BRU
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Re: Si5351 frequency controled by GPS
Those who seek will find. We are waiting for the photo of what you created.
--
Gyula HA3HZ
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VE6LX
tomekdm sp7etd
Aaron K5ATG
Bruce W4BRU
HA3HZ