Re: Sbitx high swr on a 1 to 1 antenna
Will open things up later this weekend. ?Also notice another change, on 20 meters getting more power out for a give drive setting, a (FT8) setting of 65 was good for 2 watts, now 7 to 8( measured on the out board meter). Sent from me and my iPad
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On May 17, 2025, at 8:26?AM, Scotty R via groups.io <Theroadcalls1@...> wrote:
? Have you made any progress?
Scotty On Thu, May 15, 2025, 12:40 PM W1WCI via <timothy.macdonald= [email protected]> wrote: Sbitx - antenna switch - swr/power coupler - antenna
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Previously radio showed power and 1.0 swr on 15, 20, and 40 meters with similar readings on the off board meter.
As of this morning swr on the radio and the off board meter show high SFR 2 to 3:1.
Removed the radio from the antenna line and replaced it with an antenna analyzer, it shows a perfect 1:1.?
Another radio shows 1:1 on the radio and the off board meter.
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Previously, maybe a month ago I had the same problem, spent time chasing down the antenna to no avail. Then one day all was well with no intervention at or in the radio.
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All bands that were workable for the antenna show the same behavior today.
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Trouble shooting help welcomed.
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Tim
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Re: ZBitx Shutdown Function
#zbitx
This has been covered in another thread fairly well.? The TL;DR is that even though the main computer is running an OS, very little data is being written, so it's safe to operate it like a controller and pull the plug.
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Even well behaved Pis corrupt and SD card from time to time, so it's "always" a good idea to have a ready backup or three regardless.
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73, Andy
(Sysadmin/netadmin of a mixed Windows/*nix/Solaris monstrosity in a past life.)
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Re: Sbitx high swr on a 1 to 1 antenna
Have you made any progress?
Scotty
On Thu, May 15, 2025, 12:40 PM W1WCI via <timothy.macdonald= [email protected]> wrote: Sbitx - antenna switch - swr/power coupler - antenna
?
Previously radio showed power and 1.0 swr on 15, 20, and 40 meters with similar readings on the off board meter.
As of this morning swr on the radio and the off board meter show high SFR 2 to 3:1.
Removed the radio from the antenna line and replaced it with an antenna analyzer, it shows a perfect 1:1.?
Another radio shows 1:1 on the radio and the off board meter.
?
Previously, maybe a month ago I had the same problem, spent time chasing down the antenna to no avail. Then one day all was well with no intervention at or in the radio.
?
All bands that were workable for the antenna show the same behavior today.
?
Trouble shooting help welcomed.
?
Tim
?
?
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On May 16, 2025, at 02:24, Jon / W2JON via groups.io <sigmazgfx@...> wrote:
Ahh, okay..
Thanks for clearing that up.
Why not do some development for the z?
It could use some love in certain areas. Yep. And of course the goal is to run the same software on both anyway. That¡¯s what I do. The pi in the zbitx is not as fast, but still ok to compile on, actually. I remember when a Pi 3 was the fast new kid on the block, and it¡¯s as fast as that.
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Re: ZBitx Shutdown Function
#zbitx
This is not about the sBitx - as you can see by the subject, this shutdown is for the ZBitx that is designed to be shut down by just pulling the power plug.?
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Karl Heinz - K5KHK
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Re: ZBitx Shutdown Function
#zbitx
If you can log in via a terminal, that¡¯s of course easy to do, but when portable without a computer (or, if you don¡¯t have an active terminal connection) then you need a way to properly shut down the Pi Zero. The Pico is not running an operating system or has any external storage that needs to be synced , there is no risk in just disconnecting the power.?
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Karl Heinz - K5KHK
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Re: Update On Shipping Delays from HF Signals
Hello Randy Rxxxxxxxx,
Your Order# 3948 has been shipped.
The tracking details are :
Transporter : DHL
Tracking ID: 790xxxxxxx
On its way!!!
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Thank you,
randy.ab9go@...
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Re: zbitx, compiler optimizations
#zbitx
Great work , Laci!! ?This system will get better !! This is real ham radio?
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gordon kx4z?
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Re: zbitx, compiler optimizations
#zbitx
It would be worth investigating the possibility of shading. Shield the entire front panel and the connecting ribbon cables.
In sbitx, I shielded the cable from the RPi to the display controller and the area between the RPi and the pcb.
As a result, I can control the reception sensitivity (IF) to a value of 80-90 instead of 60 (depending on propagation).
I insulated the shielding with 50 mm wide copper foil and the copper surface with Kapton tape of the same size. (Kapton can withstand higher temperatures).
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?rdemes lenne megvizsg¨¢lni az ¨¢rny¨¦kol¨¢s lehet?s¨¦g¨¦t. A teljes el?lapot ¨¦s a hozz¨¢vezet? szalagk¨¢beleket is ¨¢rny¨¦kolni.
Az sbitx-ben az RPi-t?l a kijelz? vez¨¦rl?h?z men? k¨¢belt ¨¦s az RPi ¨¦s a pcb k?z?tti ter¨¹letet ¨¢rny¨¦koltam.
Ennek k?vetkezt¨¦ben a v¨¦teli ¨¦rz¨¦kenys¨¦get ?(IF) 60 helyett 80-90 ¨¦rt¨¦kig (terjed¨¦st?l f¨¹gg) tudom j¨®l szab¨¢lyozni.
Az ?¨¢rny¨¦kol¨¢st 50 mm sz¨¦les r¨¦zf¨®li¨¢val ¨¦s a r¨¦zfel¨¹letet ugyanolyan m¨¦ret? Kapton szalaggal szigeteltem le. (Kapton magasabb h?m¨¦rs¨¦kletet elvisel).
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Gyula HA3HZ
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Re: ZBitx Shutdown Function
#zbitx
RPi4 is built into the sbitx, the command line exit is not enough here either, after that the power supply must be switched off as well.
If you don't turn it off, it will remain under constant power. I have been using the command and power off for a year and a half now.
So far I have forgotten to turn off the power once and after about 5 hours I couldn't start it, I had to use the backup to restore.
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Gyula HA3HZ
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Re: zbitx, compiler optimizations
#zbitx
HI! I found that all the noise is caused by the front panel and the front panel communication. I set it up with an external monitor and without the front panel. The radio became silent without the front panel. It would be a great improvement if the display and the market could be turned off in the menu. The display could turn on the next time it is turned on. If this is not possible, I will install a mechanical switch. HA8LKT Laci 
Sgawn, i think Dbus may be used for that
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Bought a Zbitx in Dayton es no receive, ?Hook a long wire to it es there is no change in signal or noise.? Guess it's back to the booth to have a visit with Ashhar in the morning?
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Re: zbitx, compiler optimizations
#zbitx
Sgawn, i think Dbus may be used for that
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https://www.baeldung.com/linux/dbus
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Re: Z bitx poor sensitivity
I've had display noise stuck in my head, but that doesn't seem to be the issue.? Decided to do a quick noise test before bed and the display is very noisy, but nearly none of the noise makes it through the upper PCB.? Had to be careful without a insulator on the probe.? Only noise I was really seeing under the top was around where the display pins that stick through the upper board as seen around 33 seconds in the video.? Almost clipped the pins of to shorten the 'little antennas', but need to get to bed.?
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With how the case is made the 4 corner screws don't electrically tie the back plane and the 2 PCBs together.?
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Re: Z bitx poor sensitivity
It's just a pin header.? I'm just starting with the zbitx, so lots of things on my list of "hows this work" still lol?
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Re: Z bitx poor sensitivity
Look at the schematic and try to figure out what speed of communications is happening between them. Then try to match the type , cabling or shielding to match what would work there. ? I once tested a 6 foot I2C line and it worked perfectly.
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On May 16, 2025, at 21:06, Cory Lytle KO4SWI via groups.io <clytle374@...> wrote:
? Well, the difference between 500W and 5W is 20db, so I can by that much easily.? It seems that the receiver has plenty of gain as I can get the noise very loud.??
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One thing is that switching between dummy load and antenna is less than S meter bar difference.? And the bands were very noisy that day.?
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I'm going to build a little cable for between the main and display board, think I can get away with a couple inches before I get errors??
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Re: Z bitx poor sensitivity
Well, the difference between 500W and 5W is 20db, so I can by that much easily.? It seems that the receiver has plenty of gain as I can get the noise very loud.??
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One thing is that switching between dummy load and antenna is less than S meter bar difference.? And the bands were very noisy that day.?
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I'm going to build a little cable for between the main and display board, think I can get away with a couple inches before I get errors??
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Re: zbitx, compiler optimizations
#zbitx
Any sensitivity issue should be solvable. And at the worst, you might have to add a one transistor preamp. Ashhar maximized dynamic range somewhat over sensitivity so it would work in highly congested environments.?
I suspect there are digital noise signals that will have to be tamed with a wee bit of shielding
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On May 16, 2025, at 18:50, Jody - K3JZD via groups.io <k3jzd.jody@...> wrote:
? Shawn,
?
You are thinking out into the future much more than am..? Quite honestly, I'm just trying to justify the purchase of my zBITX.? My focus has been on getting the mode that I like to use (Straight Key CW using QRP) to the point where it is usable.? However whenever I read the parallel posts talking about poor sensitivity, I have to wonder if I'm beating a dead horse.? If I cannot hear other QRP signals after I get it sending Straight Key CW to my satisfaction and put it on the air,, it will collect dust on the shelf.? ?I am not going to tear into the hardware and throw more money at it.?
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72,
Jody - K3JZD? ??
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Nice contributions, Gyula. Many thanks.
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Bill VK7MX
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Re: zbitx, compiler optimizations
#zbitx
Shawn,
?
You are thinking out into the future much more than am..? Quite honestly, I'm just trying to justify the purchase of my zBITX.? My focus has been on getting the mode that I like to use (Straight Key CW using QRP) to the point where it is usable.? However whenever I read the parallel posts talking about poor sensitivity, I have to wonder if I'm beating a dead horse.? If I cannot hear other QRP signals after I get it sending Straight Key CW to my satisfaction and put it on the air,, it will collect dust on the shelf.? ?I am not going to tear into the hardware and throw more money at it.?
?
72,
Jody - K3JZD? ??
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Scotty R
Randy.AB9GO
HA3HZ
Cory Lytle KO4SWI