Date   
Re: Ideas for AM, NB FM Demod and CW filter board

g8tdu
 

I have in fact created a FaceBook group to investigate the possibility of adding AM/FM to the uBITX and the older BITX. This group has attracted 120 members in less than 24 hours.!

I have had a few chats with Ashhar on this and he suggested using the IF frequency of 45Mhz. This limited the choice of IC's which would work at 45Mhz AM, the TDA1220 will work at this IF frequency. Kyocera make some nice 12.5Khz 6 pole filters which should work nicely with this IC.

In addition we also want to add CTCSS to the board for repeater use. Most of my VHF/UHF and above equipment is done via transverters, and i wanted FM especially for repeater use.

The new group dedicated to just this can be found here.... https://www.facebook.com/groups/2517941545160596/

Version 6 Arduino

Bob Bennett
 

I have the v6 and had up working fine (but for propagation). I tried to upload the latest sketch on Farhan’s site, but really need some guidance.

I put the ubitx_v6.3.1_code.ino in the sketch folder that when I verify it I get a fatal error that indicates that it is looking to include wire.h and EPROM.h.

Bob nz2z

--
Bob
NZ2Z

Re: ubitx #v6 Screen Speed Mod #v6

Reed N
 

I didn't see any phantom button presses in my test today, so it is one of:
a) an issue due to other code problems I was having in testing (lots of stack smash crashes early on)
b) an issue that only occurs sometimes
c) an issue that I only imagined

With two thumbs ups (N6ALT and NG1P), I'll make a PR, and take a look at setting save/restore next.

Reed

Re: IRF510 insulation question #v5

Jerry Gaffke
 

That 5.15 W/m*K means the grease is almost 6 times worse at conducting heat 
than your ceramic insulators, which were 29.3 W/m*K
.
But if that grease winds up being more than 6 times thinner than your 1 mm thick insulators,
the temperature drop across the grease will be less than that across the insulator.

Once you torque down the bolts holding the TO-220 IRF510 to your heatsink, 
that grease will be very thin indeed. 
I'd guess the grease will be more than 100 times thinner than your insulators.

I bet 99% of uBitx users just leave the IRF510 heatsinks as they found them.
No insulation (or grease) between the IRF510 and heatsink.
But they are careful not to have the two heatsinks touch each other
or anything else conductive such as a metal enclosure.

Jerry, KE7ER


On Thu, Jan 2, 2020 at 07:29 PM, Don - KM4UDX wrote:
Here is my thermal grease....5.15w/m.k
Is this stuff up for the job?

Re: No Thermal Compound #v6

Jerry Gaffke
 

I agree. 
Thermal grease is not needed for the uBitx.
On the IRF510, you would first run into trouble getting heat from die to tab.
Heat has not been a problem in normal use on the uBitx with the heatsinks provided. 

I hope my dive into thermal conductivity didn't leave folks thinking
this was something they needed to figure out.

Jerry


On Thu, Jan 2, 2020 at 07:19 PM, Ashhar Farhan wrote:
You won't need a thermal contact at these power dissipation levels. We have thousands of these working and we never reported a problem of insufficient heat transfer. On the other hand, the heatsinks themselves are insufficient over 10 watts of power. Larger heatsinks are tipping the cost of shipping over to the next slab!
- f

Re: IRF510 insulation question #v5

Don - KM4UDX
 

Jerry, many thanks for the walk through.  As normal, there is much more to everything than we think. Or at least I think.  So thanks a million (degrees C).

Re: IRF510 insulation question #v5

Don - KM4UDX
 

Here is my thermal grease....5.15w/m.k
Is this stuff up for the job?

Re: No Thermal Compound #v6

Ashhar Farhan
 

You won't need a thermal contact at these power dissipation levels. We have thousands of these working and we never reported a problem of insufficient heat transfer. On the other hand, the heatsinks themselves are insufficient over 10 watts of power. Larger heatsinks are tipping the cost of shipping over to the next slab!
- f

On Fri 3 Jan, 2020, 8:18 AM Bill, <groups191227@...> wrote:
My v6 finally arrived!  DHL found it somewhere and actually delivered this time, unlike last week!

It looks good and was packaged well.  All the parts are there with the exception of the notorious BNC nut (I have a spare).  Looking forward to building it!

While checking things out and planning the build, I did notice this:  There is no thermal compound between the IRF510s or the 7805 and their heat sinks.  I think it's a needed, so check yours before running it.

No problems with interference between pot RV3 and the amplifier heat sink some others have seen.


 - Bill KB3T

Re: ubitx #v6 Screen Speed Mod #v6

bill richardson
 

I tested and agree this is a great improvement. Thank you!

Bill ng1p


On Jan 2, 2020, at 12:03 AM, Reed N <greenkid336600+groupsio@...> wrote:

I don't have my full radio built yet, but I have spent some time speeding up the screen refresh. The screen speed increases are due to the fabulous work done by Xark: https://github.com/XarkLabs/PDQ_GFX_Libs , so my contribution on that front are purely the integration into this project.

I intentionally kept the UI fairly similar to Ashhar's original release, however it's now much faster and easier to change colors, layout, etc.

NOTE: While I've tested the UI a fair amount, I have NOT actually run a radio with this. I'd definitely appreciate feedback if anybody is willing to give it a go on a fully built rig!

https://github.com/reedbn/ubitxv6/tree/pdq_gfx_update

If the current state looks good and is working on a full-up rig, I'll create a PR before tackling other code updates.


Reed

No Thermal Compound #v6

Bill
 

My v6 finally arrived!  DHL found it somewhere and actually delivered this time, unlike last week!

It looks good and was packaged well.  All the parts are there with the exception of the notorious BNC nut (I have a spare).  Looking forward to building it!

While checking things out and planning the build, I did notice this:  There is no thermal compound between the IRF510s or the 7805 and their heat sinks.  I think it's a needed, so check yours before running it.

No problems with interference between pot RV3 and the amplifier heat sink some others have seen.


 - Bill KB3T

Re: Manual for v5 #v5

James Giercyk
 

Eureka.....I see it.  My eyes aren't what they used to be.  It is in fact a v5.  Thanks to all for helping a blind man see the light.  :)



Sent via the Samsung Galaxy S10+, an AT&T 5G Evolution capable smartphone


-------- Original message --------
From: Mark - N7EKU <n7eku@...>
Date: 1/2/20 4:27 PM (GMT-05:00)
To: BITX20@groups.io
Subject: Re: [BITX20] 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: Remote cooling fan indicator #ubitx

Don - KM4UDX
 

On Sun, Jun 17, 2018 at 07:04 PM, Joe wrote:
pi filter with a series resistor in the middle
Joe, is this the circuit? But where this has the inductor, I would use the 2-10 ohm resistor, right?

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