Date   
Re: IRF510 insulation question #v5

Jerry Gaffke
 

Looking again at the ebay listing, those guys are much thicker than the TO-220 insulators I am used to.
Listing says they are 1 mm thick, so 40 times thicker than I was calculating for.
So the temperature rise across that insulator is 40 times what I calculated, or 0.085*40 = 3.4 degrees C
for 10 Watts of heat out of a TO-220 tab.

Makes sense, they are ceramic, anything too thin would fracture easily.
There are much thinner insulators, but they are made of material (such as mica) with much lower heat conductivity.
Given that these are ceramic and will not conform to metal surfaces when compressed, 
an appropriate heat sink grease is especially important.

Jerry


On Thu, Jan 2, 2020 at 05:25 PM, Jerry Gaffke wrote:
That is less of a temperature difference than I expected, perhaps someone will see an error in my math?

Re: ND6T's AGC and Nextion display issues

 

Solved my issues with the AGC board.  Open wire (DUH, some wire can't get any cheaper) and then I replaced the .1uF input cap (from the audio hi side) with a .01uF.  Now the overall audio is not effected, yet the S meter works just fine...
Your mileage may vary,
JR

Re: IRF510 insulation question #v5

Jerry Gaffke
 

Don,

The math of heat transfer is not just too bad.
Here's how I would calculate it:

What does 29.3 w/m*k mean?
Assume you have a huge cube of this material that is 1 meter on a side.
Apply heat to one side of the cube, and have a heat sink at a fixed temperature
on the opposite side of the cube.  We assume no heat is otherwise lost to the environment.
If 29.3 watts of power is applied, that side of the cube will (eventually) be one degree Kelvin
hotter than the heat sink.   

A change of one degree Kelvin is the same as a change of one degree Celsius,
so I will just use Celsius from here on out.


Assume your insulator is 0.025 mm thick, or 0.000025 meters.  (About a thousandth of an inch.)
The surface area of the IRF510 from which we conduct the heat is around 1 cm by 1 cm, or 0.0001 square meters.
You are getting 10 Watts of RF out of that single IRF510 at 50% efficiency, so it is dissipating 10 Watts as heat.
How hot will the IRF510 tab be if the heatsink can be kept down at 30 degrees Celsius with a fan?

We divide the thickness into the area and reduce those dimensions to a single value of 0.0001/0.000025 = 4 meters.
Not terribly intuitive, but that's all we need to know about the geometry to do this heat conductivity calculation.
As the area increases, the amount of heat that can be transferred increases proportionally.
But as the thickness is increased, the heat has a proportionally harder time moving through it.


The material will have a 1 C temp rise with 29.3 Watts applied and a 1 meter figure of merit for the geometry.
Our 10 Watts is less than their 29.3 Watts,  so that temp rise to be (1 degree C) * 10/29.3 = 0.341 degrees C
Our geometry has a large area for the thickness, so the temperature rise is even less: 0.341 / 4 = 0.085 K

So the IRF510 side of the insulator is 0.085 degrees Celsius hotter than the heatsink side.
And is at 30.085 degrees C.
That is less of a temperature difference than I expected, perhaps someone will see an error in my math?


Inside the IRF510 it's a different story.
Page 2 of the datasheet says thermal resistance from silicon junction to the tab of the IRF510 case 
is 3.5 degrees C per Watt, plus an additional 0.5 degrees C per Watt from tab to a well greased heat sink.
    https://www.vishay.com/docs/91015/sihf510.pdf
So the silicon die inside the IRF510 is at (10 Watts * (3.5+0.5)) + 30.085 = 70.085 degrees C. The datasheet also states that the IRF510 will work OK with a die as hot as 175 C (though it likely won't last very long).
The interface from IRF510 tab to the insulating material and from the insulating material to the heat sink
is surprisingly problematic, given the 0.5 degrees C per Watt figure from the IRF510 datasheet. There will likely be another 0.5 degrees C per Watt temp rise between the insulator and the heat sink. Without heat sink grease, these temperature differences will be considerably greater. Using appropriate heat sink grease appears to be far more consequential than choosing the correct insulating material.

Jerry, KE7ER



On Thu, Jan 2, 2020 at 03:23 PM, Don - KM4UDX wrote:
Ted and Co...this insulator has a Thermal conductivity: 29.3w/m.k.  And that number is bigger than the silicon type insulator (but I can't find the number for that....suspicious? sure...)

Yes I have too much time on my hands...but these look like the bomb.  And given that the net heat transfer is a bunch of terms multiplied (or divided), then a higher number improves heat transfer.

Note, I don't actually know what that means really, but the math looks like a bunch of linear operations, so if one term changes by half, then the end thing changes by the same relative amount. Clearly I'm at the end of my technical understanding. But...

https://www.ebay.com/itm/10x-Alumina-Ceramic-Transistor-Triac-Thyristor-Insulator-Protection-mica/153508779960?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Don

Re: IRF510 insulation question #v5

Don - KM4UDX
 

Ted and Co...this insulator has a Thermal conductivity: 29.3w/m.k.  And that number is bigger than the silicon type insulator (but I can't find the number for that....suspicious? sure...)

Yes I have too much time on my hands...but these look like the bomb.  And given that the net heat transfer is a bunch of terms multiplied (or divided), then a higher number improves heat transfer.

Note, I don't actually know what that means really, but the math looks like a bunch of linear operations, so if one term changes by half, then the end thing changes by the same relative amount. Clearly I'm at the end of my technical understanding. But...

https://www.ebay.com/itm/10x-Alumina-Ceramic-Transistor-Triac-Thyristor-Insulator-Protection-mica/153508779960?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Don

Re: Nextion Display issues

Mark Hatch
 

Joe is 100% right here. The Spectrum display, CW, Signal strength, and any other graphs have to be changed programmatically. And it gets real ugly, really fast. Load up one of the screens in the Nextion editor and go look at the "timer" tabs and try to sort them out. You have to figure out where the top and bottom of the graph are located on the display, scale the data to fit into that location, draw one color for the signal, one for a peak (in some case) and black for the other ones to blank things out (and I think you do this top down). And then, if you have any vertical red lines like a couple of the display, you need to draw them too.

Not trying to dissuade you here. Very doable. "Just Math". But plan on spending 5+ hours per graph....

73
Mark
AJ6Cu

Re: Nextion Display issues

the.chaotician@...
 

Amazing,

That did the trick, many thanks Mike!

Cheers,

Matt H

Re: ubitx #v6 Screen Speed Mod #v6

Reed N
 

Hi Joel,

You gave me quite the scare! I'm relieved to hear the black bar is not a real issue :)

I'll take a look into the phantom button press stuff and see if I can sort that out tonight (after work), since the USB/LSB switching definitely is a usability issue.


Reed

Re: ubitx #v6 Screen Speed Mod #v6

 

Reed,

The black space on the right side of the display is normal, sorry,  it is kind of dead space  where the address lines interface to the display.

Joel
N6ALT

Re: ubitx #v6 Screen Speed Mod #v6

Reed N
 

Hi Joel,

Thanks for the feedback!

With regards to the dial being sensitive, I've noticed the same thing. It's definitely something there should at least be a "sensitivity" option for. I don't plan on tackling that particular thing until I'm happy with the screen, though.

I haven't looked into the setting storage/retrieval routines, so there may be a simple fix for the USB/LSB issue you're seeing, or it could be something else going on. I think I recall noticing that there was a phantom button press near the screen center at startup at one point, so I may have to investigate that aspect too, since a phantom button press on USB (which is near the center) would cause that issue too.

I have no such black/empty space on the right of my screen. Can you send over a picture? I just uploaded a comparison clip to https://www.youtube.com/watch?v=CCpBttBYg20&t=0m53s. It's not going to be identical to what you see, since it's a few commits old, but it's representative of what I'd expect you to see, importantly with no large blank space on the right.


Reed

Re: Alternatives to Baofeng mic?

Steve Sawicki
 

Dave and All,
At one time I was the point for purchase of  100 UV-5R's  "packages" which included the high capacity battery and the speaker/mike to be used as club "give always"  for new licensed members.
What we discovered after assembling and programing the radios was that the  speaker/mike came from a different "manufacturer" .we had to do ALL of the clean up portions with drills and the interesting parts where that some of the mikes where not even soldered, incorrectly soldered.
After the rework and the installation of a foam backing the mike and speaker where total acceptable.
Did that to my Kit mike ,suriosly thinking in activating the speaker.
I guess that was partly the explanation as to why we got the UV-5R "package" for under $20 each
73's
Best Regards.
Steve AB2ET/4.

Re: uBITX V6 Headphone Jack not Working Correctly

howard winwood G4GPF
 

Easy to convert the jack to output to stereo phones. Yes! The audio is mono but is nice to have output to both L and R ears. It will not affect the lm386.

Re: ubitx #v6 Screen Speed Mod #v6

 

Hi Reed,

One more thing on a positive note, the display seems to be a lot higher resolution now, it looks sharper and clearer than before. Nice.

Joel
N6ALT

Re: ubitx #v6 Screen Speed Mod #v6

 

Hi Reed,

The upgrade was very straight forward, it worked first time. A few things I've noticed is, every time I turn the radio on it goes to the 40 meter band where I left it, but its on USB every time even though I was using it on LSB when shut off. Also I find the tuning to be very critical, I just slightly touch the encoder and its gone off frequency, also is very hard to precisely tune to the exact frequency. I noticed that there is a 3/16 slice of black on the right hand side of the display that could be utilized, (I'm sure you know about this already). The style is okay the way it is, maybe there is a better way but I don't have much imagination in this regard, as long as it is functional I am happy. I have had all afternoon to use it since my last post and I find it quite usable now. Thanks for your hard work in this regard. I would be happy to test any further changes you make.

Joel
N6ALT

Re: Damage?

Mark Hansen
 

More info - I can access the menu and Setup while the rig is in transmit mode. I can do the Calibrate operation - sort of - and if I select some value and save it, the rig drops out of transmit. No receive audio, tho, nor can I tune to a frequency. When I exit setup, it goes back into CW transmit. I don't believe it is actually transmitting a signal into my dummy load.

The rig was operating normally until I messed up the connections.

Re: Nextion Display issues

Mike WA0YCN
 

Go to the Files section (at the left) and search for "3.5".  You'll get a list similar to the one in the image below. 

At the bottom of that image are the two .tft files (dated 4/30/19 and 5/1/19) that have worked for me - one for the Basic Nextion, the other for the Enhanced.

Re: ubitx #v6 Screen Speed Mod #v6

Reed N
 

Hey Joel,

Sounds like you got it up and running! Thanks for trying the code out. Did you run into any specific issues? Were you able to use the radio normally after the update?

What tuning/improvements to the UI would you like to see? Is there a certain style or layout you think would be better?


Reed

Re: uBITX V6 Headphone Jack not Working Correctly

Dennis Zabawa
 

Referring to the schematic, the Ring and Tip of the Headphone jack are wired together and connected to the output of the audio amplifier.  The switched contacts of the Headphone jack are wired together and connected to the 2 pin Speaker header.  When a headphone, mono or stereo, is plugged in, the internal speaker should be silenced.  Since that is not happening, something is wrong with the jack, installation or PCB.

Re: Nextion Display issues

Joe Puma
 

Yes, not only do you have to resize graphics, you have to reposition all the layer objects and the custom graphs for spectrum analyzers needs to be changed programmatically too. I reworked a 5“ inch and it was completed by Mark Hatch which are in the files  section.  

Joe
KD2NFC 



On Jan 2, 2020, at 4:18 PM, the.chaotician@... wrote:


You must resize it on your own. It’s not an easy task though. 
Do you mean that I'm going to have to redesign the UI myself using the Nextion software?

Also, I don't think that I'm getting communication between the Raduino and the Nextion, is there some sort of troubleshooting process I can go through?

Thanks for your time,

Matt H

Re: Manual for v5 #v5

 

James,

Look on the back right corner of the main PCB near the antenna connector.  The version number is printed there. 

Be sure to check ubitx.net, hfsignals, and the wiki here for info. 

73,


Mark

Re: Nextion Display issues

the.chaotician@...
 

You must resize it on your own. It’s not an easy task though. 
Do you mean that I'm going to have to redesign the UI myself using the Nextion software?

Also, I don't think that I'm getting communication between the Raduino and the Nextion, is there some sort of troubleshooting process I can go through?

Thanks for your time,

Matt H