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Re: Need Help setting the PA Bias Current for sBITX
Aaron, you are doing great! As a former RadioShack tech, I can tell you that getting stable power in the item is always first. Although inconvenient,? this radio troubleshooting will make you an expert on the design and components.? As a teen in late 70s,? I had almost memorized the schematics of the Heathkit hw101 transceiver.? So many modifications and repairs led to that. This radio is completely different,? but keep up the good work and efforts. Document everything and be proud of your achievements. Scotty WD4PYT On Wed, Jun 12, 2024, 11:13 AM Aaron K5ATG via <Aaron=[email protected]> wrote: CORRECTION: |
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Re: Need Help setting the PA Bias Current for sBITX
CORRECTION:
This doesn't use a SI5351. What I was calling a SI5351 is actually a If anyone notices that I'm making a mistake like this or something then please correct me. I don't have a PHD in electronics and I have not been a ham who has been building this stuff for decades. Don't assume that I know it cause I don't. My goal here is to be able to get back on the air with this so I can start off learning easier to understand electronics and get more complicated as I go. Trying to figure this out, I mean yeah I'm learning some but still it feels like I have jumped in the deep end of the pool with cement shoes on.? I really appreciate all of the help that people has given me. I really don't know if I'm making more mistakes and making it worse as I go.? Now i have learned how to measure current (I even made a cable to do this) and how to replace parts, getting lots of experience in replacing parts. I try to look at the schematic and use that to find my way on the PCB but it is still way over my head.?? -- '72 Aaron? |
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Re: How hot is too hot?
I think your train of thought is missing a few things. The CPU is a circuit board corresponding to many transistors, the measurement is performed on this board. When you switch on the power supply, the temperature at the point of measurement rises very quickly. It is worth reading about it with the help of google. You can find a lot of useful and uninteresting information.
-- Gyula HA3HZ |
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Re: How hot is too hot?
JJ,
I don't think the CPU Temp gauge is accurate. This morning with my shop and my sBitx V3 at 64F, I booted my sBitx up to find the starting temp to show 30C or 86F indicated. If accurate it should have shown around 18C. Yesterday at end of day right before I shut the sBitx down for the night, the temp was indicated to be 76C or 169F, I find that to be a bit too hot being as I was only running the sBitx program all day. Am I looking at this right or am I missing something? Joel N6ALT |
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Thanks Gyula?
? I got JTDX working and on the sBITX and successfully used the sBITX Toolbox larger virtual screen. One anomaly I noticed is that output power is about half what I get in CW with the same drive setting. I suspect that the audio level is too low, even with the JTDX power slider all the way up. I didn't see a way to adjust the level. -- 73 ??? Bob? KD8CGH |
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Re: Need Help setting the PA Bias Current for sBITX
Aaron, Sounds like ur making headway. reverse polorizing a unit sometimes takes patience to work out all the weakened components or some that wont fail unless its under load. I dont own the SBITX yet, but it seems from the info you provided its now isolated to the transmit sections. I would start by looking at the si5351 area and where the Pi connect since you actually witnessed some smoke. where there is smoke, there is char, or holes in something or burnt traces. check driver transistors, and anything feeding the finals. Also check your interconnecting wires for any burn marks or punch thru holes .Since you are actually receiving stuff, i would say your si5351 and PI are good, unless the si5351 had one osc crap out .It has 3 outputs. order a si5351board asembly which are cheap, and replace the one in your Sbitx. . Also look for any interconnecting components leading to these items on the board such as traces burnt, resistors discolored, etc. You are doing great. you got the receive up and running!!!!!! . recheck ur fets and also any driver transistors and pre amp transistors.Also check ur biasing resistors for opens. Good luck on ur repair Aaron. You have made alot of headway since u are receiving stuff and power is flowing back into the unit. might check your voltages on your finals , and anything up stream from the finals. Sounds like ur getting very very close. GOOD JOB!!!!!! 73 David ac9xh
On Tuesday, June 11, 2024 at 10:42:15 PM EDT, Aaron K5ATG <aaron@...> wrote:
Hello All, Yup still trying to get my sBITX working again. Here is a recap.? Back in March I accidently cross polarized the transceiver First thing I did was to replace both IRF510's? Q16 & Q17 That didn't work so I found that D7 Needed to be replaced. I replaced it with another 1N4007 Diode ( I think that this is intended to protect the circuit in case of cross polarization. It didn't work that in my case.? I then replaced the voltage regulator with the suggested Drok Voltage Regulator I then would turn it on and would get wisps of smoke and the smell of burning electronics. I could not locate the source of the smoke but it was coming from the area around the SI5351 and RPI. A couple of days later I pulled the SI5351 out to look at it and returned it and powered up the transceiver and there was no smoke or smell of electronics burning.? I hooked it up to an antenna and it was receiving very good, 'Next I hooked up a dummy load to it and put it in transmit and it would completely shut off immediately Next I was told that I need to set the PA Bias since I replaced the IRF510's? in order to do that I had to follow these steps:
No idea on how to measure the current with a digital multimeter so I had to do some cinematic research on how to do it. I basically had to put the DMM probe in the right socket on the DMM and put the DMM in the circuit. Here is a pic of what I did (i apologize for the crudeness of the image, I just rushed through it)? When the sBITX is in Receive the DMM displays a 0.43, when it goes into transmit it jumps to 0.86. Before I hooked up the DMM to start adjusting the? ? ? ? ? ?PA-BIAS1 I set it to zero (full counter clockwise.) When I adjust PA-BIAS1 there is no change to the DMM readings in either receive or transmits.? This is where I'm at now and I'm unsure what tunnel in this never ending maze of tunnels to take in eventually getting this radio back on the air. I'm starting to wonder if it ever worked in the first place and my recollection of me enjoy using it is just an illusion within the confines of my cerebral carnival.?? -- '72 Aaron?
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Need Help setting the PA Bias Current for sBITX
Hello All,
Yup still trying to get my sBITX working again. Here is a recap.? Back in March I accidently cross polarized the transceiver First thing I did was to replace both IRF510's? Q16 & Q17 That didn't work so I found that D7 Needed to be replaced. I replaced it with another 1N4007 Diode ( I think that this is intended to protect the circuit in case of cross polarization. It didn't work that in my case.? I then replaced the voltage regulator with the suggested Drok Voltage Regulator I then would turn it on and would get wisps of smoke and the smell of burning electronics. I could not locate the source of the smoke but it was coming from the area around the SI5351 and RPI. A couple of days later I pulled the SI5351 out to look at it and returned it and powered up the transceiver and there was no smoke or smell of electronics burning.? I hooked it up to an antenna and it was receiving very good, 'Next I hooked up a dummy load to it and put it in transmit and it would completely shut off immediately Next I was told that I need to set the PA Bias since I replaced the IRF510's? in order to do that I had to follow these steps:
No idea on how to measure the current with a digital multimeter so I had to do some cinematic research on how to do it. I basically had to put the DMM probe in the right socket on the DMM and put the DMM in the circuit. Here is a pic of what I did (i apologize for the crudeness of the image, I just rushed through it)? When the sBITX is in Receive the DMM displays a 0.43, when it goes into transmit it jumps to 0.86. Before I hooked up the DMM to start adjusting the? ? ? ? ? ?PA-BIAS1 I set it to zero (full counter clockwise.) When I adjust PA-BIAS1 there is no change to the DMM readings in either receive or transmits.? This is where I'm at now and I'm unsure what tunnel in this never ending maze of tunnels to take in eventually getting this radio back on the air. I'm starting to wonder if it ever worked in the first place and my recollection of me enjoy using it is just an illusion within the confines of my cerebral carnival.?? -- '72 Aaron? |
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Re: sBITX 64Bit Pi Image Available
#sBitx
Ashhar, that's your reward for producing such a finished and professional looking transceiver. The uBitX, the -40, etc, were clearly experimental and not all done so no surprise.
As I crawl through all my tests on my V2 with TVS and V3 software plus the fixes I'm finding a better and better unit. The receiver is outstanding as have been your past designs. I expect in a year or so, all the issues will be done and a ham not so interested in experimenting, will find a fine transceiver. Since a separate computer is not needed for logging, digital modes, QRZ lookup, and web access, it is an impressive compact radio+computer. 73, Bruce, W4BRU |
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Re: sBITX 64Bit Pi Image Available
#sBitx
Remote ssb hf? On Tue, Jun 11, 2024, 2:19?p.m. JJ - W9JES via <w9jes=[email protected]> wrote:
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Joel Caulkins/N6ALT
Scotty R
Aaron K5ATG
HA3HZ
Bob Benedict, KD8CGH
Bruce W4BRU