|
Being very clever, I managed to completely smoke my SBITx board.? (don't ask).? I am planning on purchasing just the board but want to make sure nothing has changed in the basic "box" that would preclude me just replacing the broken main board.? ?Can anyone comment on this?
|
I can't answer the question - but I wanted to mention I completely burned off a length of power trace near the MOSFETS. It was a mess and smelled terrible. I was able clean the board off and solder a heavy solid wire between the remaining trace ends. It now works well and after a month or so the smell has receded. Even if it looks bad you may be able to save yours.
--
73
??? Bob? KD8CGH
|
Thanks for reply.? Actually I melted the Mosfets and a couple of other components.? Tried replacing the mosfets but it just dies if I try to transmit.? So I am? sure I did in lots of other stuff.? I did not, however see that the power trace was damaged.??
|
Yeah - it takes a special mistake to turn it into a toaster. I initially used a current limited bench supply which is safe but limited to a max of 5 amps. After a few successful uses I thought the sBITX was safe. When it blew yet another MOSFET I didn't rush to turn it off, thinking the bench supply current limit had tripped. I forgot that the previous session I had moved the sBITX to the 30 amp main power supply. The trace separated before the 25 amp main fuse blew.
Amazingly enough, after fixing the trace and replacing the MOSFETS, it worked.
BTW - no problems since I polished the heat sink, switched to aluminum nitride insulators and added back to back zeners.
--
73
??? Bob? KD8CGH
|
That’s why I did all of those upgrades also
I suspect if you reverse the polarity you can really screw up the whole board.?
For me, this is a lot of money invested in 2 very experimental radios. ? So I have polarity protectors on both of these expensive experiments!!!!! ??
Powerpoles are nice, but the way that everybody always does the smoke-letting is they reverse the Clips on a battery or on a power supply that DIDNT have power poles….. ?It’s not the power poles. It’s the thinking when you’re tired and you have to reconnect something with Clips or spade lugs or something?
I have it on my go box also. And we have it on all the rigs down at the EOC. ?The relay/diode idea would also work just fine. No argument against that.?
Everybody gets to pick how they want to do things. ? I just know I can do stupid things. ? Been there, done that?
toggle quoted message
Show quoted text
On Dec 11, 2023, at 19:16, Bob Benedict, KD8CGH <rkayakr@...> wrote:
?Yeah - it takes a special mistake to turn it into a toaster. I initially used a current limited bench supply which is safe but limited to a max of 5 amps. After a few successful uses I thought the sBITX was safe. When it blew yet another MOSFET I didn't rush to turn it off, thinking the bench supply current limit had tripped. I forgot that the previous session I had moved the sBITX to the 30 amp main power supply. The trace separated before the 25 amp main fuse blew.
Amazingly enough, after fixing the trace and replacing the MOSFETS, it worked.
BTW - no problems since I polished the heat sink, switched to aluminum nitride insulators and added back to back zeners.
--
73
??? Bob? KD8CGH
|
Hello,
i have a question that’s been on my mind for awhile. Would the v2 mainboard work in the Developer Edition case?
I have had a few problems with my Developer Edition mainboard. That darn guy who was doing the 2nd, I believe was the last upgrade, upgrade burnt up quite a few of the traces. Opps ?I forgot that guy was me, (don’t ask). So I thought since there have been quite a few improvements in the newer edition main board that it would probably be easier to just buy a new mainboard.?
what does everyone think, will it work? I know there has been changes to ?where the mosfets have been placed so I would have to make some changes for the heatsink placement. What about the access to the Raspberry Pi’s ports also? The power plug would have to be resoldered. By the way I really like the idea of reverse power protection. Is there any other changes I have missed, besides the whole mainboard is now vertical instead of horizontal, Hi Hi.
take care , 73
Robertt, AG6LK?
|
Hello,?
someone has to have some thoughts on this idea, I hope.
73,
Robert, AG6LK?
|
1. The v2 and v3(which is v2 with a few component values changed) can't be mounted in the old cabinet. It will require pretty brutal work to stuff it in. The side panels will have to be redone and the back panel too. 2. I developed all the versions on rpi 4 with 2gb RAM. The sbitx runs even on the rpi zero 2w. I keep going between the two. - f
On Thu, Dec 14, 2023, 8:42 AM Robert AG6LK < amrmedic@...> wrote: Hello,?
someone has to have some thoughts on this idea, I hope.
73,
Robert, AG6LK?
|
Ashhar,
thank you for the information.
is there any thoughts on selling just the v2 case and mainboard together yet?
Thank you, 73
Robert, AG6LK?
|
By old cabinet do you mean the development one.? I purchased the V2 and that is the one where I want to replace the main board with the one that is currently for sale.? So my question was would that board fit in the case I have.
Thanks for the response.
|
The sBITX v3 was just announced on this list. You can buy the board only for $180, or the complete radio (including case, display, and 2GB Raspberry Pi 4) for $399.
By old cabinet do you mean the development one.? I purchased the V2 and that is the one where I want to replace the main board with the one that is currently for sale.? So my question was would that board fit in the case I have.
Thanks for the response.
|
Well this is fun!!!? ?I purchased the V3 board, installed it and all looked good.. BUT? when I tried to transmit (ssb) I got 0 watts out no matter what the "drive" was set at.? ?Maybe there is something incompatible? between the V2 case and the V3 board.? Expensive experiment.? Guess I'll put this box on the shelf as a decoration and go back to my cheap Chinese qrp boxes that work sometimes:)
|
There's also a Mic Gain setting - did you turn that up?
Have you checked power output in CW or 2tone mode?
How well does it receive?
73; Steve, N3SB
|
Mic gain is/was fine.? I tend to run FT8 a lot, so that is what I did early on.? Set drive at about 30 and did a CQ.? The display show that it was trying to transmit but showed 0 watts.? Also the power monitor I had connected to the supply side did not change while it as trying to transmit.? That suggest that, internally, the system didn't even go into transmit, i.e., it was drawing no power.? One strange thing.? When it goes into transmit it displays both power (watts) and SWR.? The SWR always seem to be 1.0 .? My antennas are not that good:)
|
FYI,
You need to make sound into the mic to get power out on SSB.? A long and loud HEEEEEELLLLLLOOOO is a good test.
73
Evan
AC9TU
|
Nomadg360,
Did the band scope display show the audio signal when you tried the CQ?? If so, then the radio IS going into transmission.? The issue is the final amp is not working, or the hw_settings.ini file does not have the correct values.? Be sure to use the microSD card supplied with the board rather than the one that came with the V2 radio.? If that does not work, post again, and we can try other tests to track down the issue.
73
Evan
AC9TU
|
You should see a couple hundred milliamps of current increase when you go from receive into transmit, just from the bias current the final transistors draw.
If you don't see that current increase, then check the resistance from the drains of the finals to the power input connection - it should be less than an Ohm.
It's also possible that the bias potentiometer got bumped and there's no longer bias voltage being applied to the gates during transmit.
Might we get your callsign and name so that we know how to address you?
73; Steve, N3SB
|
By band scope I assume you mean the display about mid display which shows, in ssb a wave form and in FT8? a solid yellow bar.? Yes I got that display each time? I did install the microSD card that came with the board. I looked for the hw_settings.ini file but not sure I found the one that is used by the radio when it is running.? I think it was in the sbitx directroy,? maybe under the data sub-directory.? That one seem to have values that made some sense.
In testing ssb, i found a clear point on the 20 meter band and called my call sign and test, test test as well as trying to respond to a POTA cq.
On the board, are there check points,? where I can test the voltages and some where i can find what values I should be seeing?
|
Hi Steve abd Evan.
As I mentioned I saw no change in the power on transmit.? I'll open it up tomorrow and see what the meter says on the finals.? (It looks like they included another set of finals with the board??)
?Gene, K4GNE
|
Gene - I believe HFSignals is providing a spare set of finals with the board. Hopefully you don't need them....
On occasion - the sBitx will start up in a "strange" mode where it doesn't receive properly. If you don't hear the typical FT8 activity on 7074 or 14074, then shut down the app and start it again. You don't need to completely power down the Raspberry Pi.
A LOT of troubleshooting can be accomplished by just observing how the radio behaves: Can you hear signals / can you see signals on the band scope / can you see transmit audio on the monitor scope, etc.
73; Steve, N3SB
|
Bob Benedict, KD8CGH
Shirley Dulcey KE1L