Pro Stick Plus - Very Hot


#1

Folks,

I’ve been a subscriber to Flightaware for some time and lately been submitting ADS-B data using a relatively cheap USB wide band TV tuner connected to my Raspberry Pi Zero that is able to receive 1090 data.

Was quite excited when I saw the FlightAware Pro Stick Plus available so purchased it.

Not happy with the heat developed, the USB and antenna connections were both quite hot to the touch (Not ouch but surprisingly hot) so what temperature the inner components were reaching I don’t know. It is after all 5V and 300mA - not exactly a power hungry device.

The puzzling bit is my cheap tuner also has a Realtek chip (Not the same) and runs cooler.

Being unhappy with hot electrical devices that are expected to run 24/7 unattended I have reluctantly returned the item.

What are other users impression of heat created?

Geffers


#2

The r820t is known to be fairly power hungry (and therefore run pretty hot). The prostick preamp adds a little too. The USB/SMA are basically acting as heatsinks - you have to get the heat out somehow.

5V @ 300mA is 1.5W which is not much but if you only have a small area to dissipate it, that does get hot.

tl;dr: it’s normal.


#3

I bought an rtl-sdr.com aluminium case with thermal pad for passive cooling of my Pro Stick Plus. It does a nice job of dissipating heat.

Though I don’t see the case alone listed for purchase on their web store site any longer, you can email them a request and ask if they will sell you their case separately.

rtlsdrblog@gmail.com

rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/


#4

If you can hold it, it’s not that hot.

If touching it blisters a finger, it’s getting warm.

If parts slide off the pcb because the solder is reflowing, then it’s hot!

60 - 70 C isn’t a problem for modern electronics.

Yes, cooler is better, and I’ve added heat transfer materials (chomerics silpads) to transfer heat away from components (more for frequency stability).

On the (MacPro) computer I’m using to write this, the CPUs are running at 57 C, IO controllers at 62 C, DIMMs around 44 C, system ambient displaying 32 C.

cheers

bob k6rtm


#5

Neither was it a problem for classic electronics of vacuum tube era :slight_smile:


#6

Great reply Bob :laughing:

Appreciate electronics get hot but mainly I was comparing with my existing much cheaper tuner which also has a Realtek chip and doesn’t feel nearly as hot/warm/mild as the flightaware device.

My Pi devices I can touch the CPU and heat is very mild, they record between 40 and 50C but the entire device feels quite mild with no cooling other than passive.hence my query.

Geffers


#7

I believe they discontinued them and had a sale on the remaining ones. Don’t know if any are left. :frowning:


#8

That’s too bad.


#9

I like the comment about vacuum tubes – yeah, they ran hot, they had to (that thermionic emission thing). And for transmit tubes (like the 6146B), not only did they run hot, the voltage on the exposed anode connector could/would/wants to kill you.

Yet these designs were manufactured to be reliable, and they were and still are. In the ham radio area, the Collins S-line of receivers, transmitters, transceivers, and power amplifiers are still prized today – and they’re filled with vacuum tubes. They were designed to keep the hot stuff (tubes) on one side of the chassis, and a lot of the other parts away from the hot stuff.

Our modern stuff I believe is more reliable (at least the hardware side of things – software is a different story entirely).

One reason is our reliance on surface-mount electronics, and the reflow soldering process.

That reflow process preheats the board and all its components to between 150 and 180 C and soaks them in that 150 - 180 C range for a few MINUTES. The actual reflow ramps the temperature up (over a minute or more, a change of 3 C per second max is the usual spec) to around 230 C for 10 to 30 seconds or so to get the solder paste to reflow, and then cools down (controlled cooling, usually 3 C per second max).

I would not like to take most of the components of a Collins S-line box through the modern preheat and soak temperature cycle! Most of the components won’t survive! They weren’t designed to!

If we look at a Raspberry Pi based ADS-B system, the Pi and the SDR are both surface mount boards – they’ve gone through the oven, quite literally. All their parts are designed to survive reflow assembly temperatures. Depending on what curves you use, that’s 6 to 8 minutes or more above 150 C. The total time spent above 100 C can be much longer, possibly 10 minutes or more.

Using a quality (micro) SD card is important – I’ve not had problems with legitimate Samsung memory. (And there are things that you can do in software, like run certain parts of the system in tmp directories that stay in RAM to reduce wear and tear on the SD card – and newer versions of the PiAware software use all these tricks).

But the core hardware has been through the oven. Even the PiAware filters are surface-mount and reflow inside (well, the connectors look like hand solder after the reflow process).

After going through that surface mount assembly process, running at 60 - 80 C isn’t a big deal.

cheers–

bob k6rtm

(You can look up components on sites such as Mouser and Digi-Key and see what their manufacturers recommend as far as reflow temperature/time profiles. You can also look up reflow soldering. Adafruit has some great videos of their automated assembly lines, from applying solder paste to boards to pick and place of components, and through the reflow oven. There are industry standards, but as as been oft stated, the great thing about standards is there are so many of them.)

(I picked up a great t-shirt that aptly summarizes the state of the art in software. https://www.amazon.com/gp/product/B01ALNJ6GY – please take a look, and congratulate obj and the PiAware dev crew for the efforts they put into building stable,reliable code. It ain’t easy!)


#10

6146B Beam Power Tube
Plate Voltage 615 Volts
Plate Input 94 Watts


#11

I miss the old tube days a bit. Look up an 833 tube, with 5000 volts on the plates and current of one amp. Huge power supply. We used this in a naval 5000 watt transmitter, with push - pull 833’s feeding a huge rhombic antenna. This was just the output amplifier, ad consumed around 7000 watts. Yes, rewiring the building was required.

Must admit, working with the Pi computers and parts is much easier.


#12

833 Vacuum Tube

833 Vacuum Tube - Push Pull Matched Pair

Push Pull Pair At Work - Cathodes Heated Red Hot to Provide Thermionic Emission


#13

Looks like a furnace rather than electronics! :open_mouth:

Pro Stick Plus temperature cannot beat this one.


#14

Tempurature thread I started in December.
http://discussions.flightaware.com/ads-b-flight-tracking-f21/flir-images-rpi-2-and-pro-stick-t38426.html

I have since purchased some of the metal cases while they were still available. The metal case gets very warm to the touch so it must be doing some good.


#15

Bob,

Superb explanation, don’t think it is the heat so much as the potential fire risk I don’t like. My logic says it’s got to get VERY hot before flames appear so cooler the better.

There is my problem, little bit of knowledge creates a worry that more knowledge can eliminate.

I do have one that ‘appears’ to run cooler, same chip manufacturer but different chip.

Geffers


#16

Autoignition points are typically at least 200C so you have a lot of headroom there.