I have been fighting bad band noise on all of my sBitx's from the DE to my V2 and V3, finally decided and set out to find another solution. I researched the most quite Buck converter that the RC and Drone users are using and they mostly agree that this is the best one,? I tried it in my V3 and found it works great with no rf noise that I can see anywhere and the general noise floor is much lower than before and the best part, it runs cool to the touch after 5 hours. I'm now going to install one in my DE now. YMMV.

Joel
N6ALT

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Hi Barry, no I haven't tried that yet, I only just saw your post regarding the .1 cap today, that would be a good fix alright and I might try that on my DE. The "Beefy" regulator that I used has the exact same specifications as the one that comes in the radio, it's 12V to 5V at 3 amps max but the CONVERSION EFFICIENCY is over 95% which makes it run pretty cool and the shielding and filtering makes it RF quiet. My V3 used to get pretty warm over on the left side of the radio because of the Mini 360 regulator, now it runs stone cold on that side. All in all, I think it's a improvement.

Joel
N6ALT

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Joel,
I would like to suggest that you read the Drok converter discussion on the keithsdr forum.
Just a small note. You put it in the v2 box and at the same time blocked the possibility of ventilation inside the box.
I just want to say that you have not placed the converter in the best place.
Of course, if you also cool the current large heatsink with an external fan, it also creates a suction from the box.
These are just the insights of an outside observer. Please don't take this as a big problem.
--
Gyula HA3HZ

On Wed, Jan 17, 2024 at 03:32 PM, Joel Caulkins/N6ALT wrote:

I have been fighting bad band noise on all of my sBitx's from the DE to my V2 and V3, finally decided and set out to find another solution. I researched the most quite Buck converter that the RC and Drone users are using and they mostly agree that this is the best one,? I tried it in my V3 and found it works great with no rf noise that I can see anywhere and the general noise floor is much lower than before and the best part, it runs cool to the touch after 5 hours. I'm now going to install one in my DE now. YMMV.

Hi, Joel.

I am finding my V3 heat sink gets very hot to the touch when running ordinary software on the Pi 4.? This means I'm not running the sbitx app, I'm just using it as a general purpose Pi host, and the heat sink gets very hot.? ?This means the heat is coming from the regulator and not from the sbitx final transistors.

So when your title says 'hot' I presume you mean this regulator can reduce temperature?

Do you have more details on how to install it?

I believe the critical section of the schematic is:



So you are simply detaching U8 and replacing it with the?DROK 12v to 5v Volt Converter?

Any other guidance?
?
--
Regards,
Dave, N1AI

Hi Dave,

Note that you are using the DE schematic rather than the V3.? I would be careful as there are differences.? The correct V3 schematic is in the sbitx folder on the RPi:
sbitx_v3_production.pdf

You should also check that R203 and R204 are not the devices causing the heat.? They dissipate around 1/2 watts each, even if the sbitx software is not running.? That is a large part of the 400 ma draw when the power is turned on before the sbitx software starts.? There are no published mods that I know of to turn off this power use.? Try removing the two resistors and see what the power draw and heat dissipation are like.? DO NOT start the sbitx software with the resistors removed.? For sure, do not transmit, as the bias for the output switching diodes is removed without those resistors.? The receiver will not work either.

There are other advantages to switching out the 5-volt buck converter on J1.? The suggested replacement has been reported as more efficient and generates less RF noise.

73
Evan
AC9TU

Hi Dave,

On the Developers Edition the HFSignals team removed the LM7805 regulator and installed a Buck regulator that just floated in free air, I just replaced this with the Drok regulator. You couldn't even touch the little regulator that they used but the new Drok regulator runs cool. On the V2 and V3 they put a female header on the main board and just plugged the Buck regulator into the header, I just mounted the Drok regulator to the back panel and soldered some pins onto the wires and plugged it into the header, over all the radio runs much cooler and is way more RFI quiet. I've included a picture of the regulator on my V3.

Joel
N6ALT

On Sun, Feb 25, 2024 at 02:59 PM, Evan Hand wrote:

Note that you are using the DE schematic rather than the V3.? I would be careful as there are differences.? The correct V3 schematic is in the sbitx folder on the RPi:
sbitx_v3_production.pdf

Yes, you are correct, I had a few tabs opened and picked the wrong one.

?has the right one for the board I'm currently concerned with.

You should also check that R203 and R204 are not the devices causing the heat.? They dissipate around 1/2 watts each, even if the sbitx software is not running.? That is a large part of the 400 ma draw when the power is turned on before the sbitx software starts.?

Are these thermally "sunk" by the heat sink?? My primary observation is that the heat sink is what gets hot.? My understanding is that the only things that the heat sink "sinks" is/are the two final transistors and the 12V-5V regulator but I am probably wrong on this, based on what you and Joel are saying.??

There are no published mods that I know of to turn off this power use.? Try removing the two resistors and see what the power draw and heat dissipation are like.? DO NOT start the sbitx software with the resistors removed.? For sure, do not transmit, as the bias for the output switching diodes is removed without those resistors.? The receiver will not work either.

What is a good way to measure power draw from the 12v battery?? I have a multimeter but don't know its current limit and probably would want fusing and a good harness to make connections are solid, etc.??

There are other advantages to switching out the 5-volt buck converter on J1.? The suggested replacement has been reported as more efficient and generates less RF noise.

Agreed.

On Sun, Feb 25, 2024 at 03:15 PM, Joel Caulkins/N6ALT wrote:

On the V2 and V3 they put a female header on the main board and just plugged the Buck regulator into the header.

Is this plug J1 on the schematic above?? ?If not, which?

Is the 'Buck regulator' shown in the schematic?? If so, what is the device 'U' number?

From your text it seems this 'Buck regulator' still just floats in air on V2/V3 and is not "sunk" by the heat sink?

Do we have any good markings on the PCB and/or a close up picture so I can locate exactly where the plug you are describing is?

Sorry I'm asking so many questions but my workarounds for this issue are no longer good enough for me.

Bonus question: Can I just plug a 5V USB-C power brick into the Pi4's USB-C power port to offload the sbitx 5V supply, or will this lead to sparks, flames, and catastrophe since we'll now have two "sources" providing 5V to the Pi??

I just mounted the Drok regulator to the back panel and soldered some pins onto the wires and plugged it into the header, over all the radio runs much cooler and is way more RFI quiet. I've included a picture of the regulator on my V3.

Thanks, and if/when you get a chance, can you post a well-lit closeup of the jack where the wires are inserted?
?
--
Regards,
Dave, N1AI

To be clear there are two issues I'm trying to address:
1) Heat sink gets very hot when Pi4 runs a moderate to heavy workload that does not utilize the sbitx radio hardware at all
2) USB devices plugged into the Pi4 fail, presumably due to low voltage

--
Regards,
Dave, N1AI

Dave,

Here is a picture of the regulator mounted to the board, circled in blue, and R203 and R204 are circled in red.



J1 is on the first page of the schematic.? There is not a U number for the device.? Joel may be able to identify the proper pins for the DROK converter.

I currently have issues with my back and can not get to my V3 in the basement for pictures with the regulator removed.

The best way to measure the power supplied to the V3 is to measure the voltage and current.? There are power meters available online if you want to purchase one.? I have this one I used for another project:


73
Evan
AC9TU

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Hi ya'll,

First let me thank those who noted the RF noise spikes that I too was getting on all bands and ordered the DROK 12v to 5 v buck converter from Amazon to hopefully correct it.

Just my 2cents to help in figuring out on how to wire it up after reading this message string from everyone.

Researching on how to install to replace the existing one as shown below by Evan's picture - AC9TU - and reading the post from?Joel - N6ALT - who has already done it;? it actually looks simple as the pin descriptions are printed on the bottom of the little regulator circuit board for ref.

Using the image below for reference, there is a 4 pin header socket that the original board is plugged into, and using the PIN #'s from the V3? Schematic? for J1 - From left to right they are...

pin 4 =>? V out

pin 3 => Ground

pin 2 => V in

pin 1 => NC - No Connection

As I haven't received the regulator yet, not certain if the ground leads from the in & the out are common & tied together, but i suspect that they are as the picture from Joel - N6ALT - doesn't show that the output side ground is hooked up.

Comments and additional details are welcome as we all can benefit from them.? I have already benefited from this group over the years working with my uBitx v6 with everyone's point of view and knowledge.

Brian - N9NAZ

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Hi Scotty,

Yes I still recommend the Drak regulator, it runs cool and has reduced noise and birdies by about 80%. Over all the radio is just more quiet than before.

Joel
N6ALT

Scotty,

I suggest using a Dupont header with the wires soldered to it and then plugging it into the mainboard socket.? The alternative is, as Joel has done (based on his picture), using crimp-on pins to the ends of the wires of the Drok.

Here is a kit from Amazon:?

You can use the solder on pin headers cut to size, or if you have a crimping tool, use the single or 4-pin plastic holders for the male pins.? ?Use the solder connectors to save the cost of a crimper.

73
Evan
AC9TU

Found a lower cost option if you are going to solder the leads:


73
Evan
AC9TU

Scotty,

Sorry for not getting back to you sooner, I have been away from home. I used a Dupont header and some heat shrink tubing to make sure there is no shorts then just plugged it into the existing header on the main board. On my DE version I actually soldered wires to the main board and drilled and screwed the Drak regulator to the side of the cabinet.

Joel
N6ALT