Hello,

This is my first vtx.
I was testing (newly bought) the eachine vtx03 by just powering it on (without camera or VRx connected). First I gave it 5V and after few seconds it becomes so hot to touch (around 160F). I immediately powered it off. Then I gave it 3.3V and kept powered on for some 10 mins. This time it was not that hot (around 115F). Is this normal behavior? Should I be worried?

Thanks.

VTXs will get hot. You want to put on antenna to disperse the heat. Even with antenna, the VTX will get hot.

(23-Sep-2018, 05:58 AM)voodoo614 Wrote: VTXs will get hot. You want to put on antenna to disperse the heat. Even with antenna, the VTX will get hot.

I powered it on with the built in antenna on it. Is 160F still fine? it might go up if I run for few minutes. Wont it burn the components?

Don't forget that when the quad is flying outside it will be getting plenty of airflow so this will cool down the VTX.

I'm not sure what power setting you have it on but when working with your quad on the bench it would be a good idea to set it to the lowest power setting with the button on the side. For a lot of VTXs this is 25mW but in the case of the VTX03 you can actually turn it off completely (0mW). The lower the power setting the less hot it should get standing still on the bench, and unless you are actually testing the video signal on the bench you don't need it outputting a video signal at all, thus the reason to set it to 0mW until you finish working on your quad.

One other point to remember in case you didn't already know. Never power on the VTX without an antenna attached because there is nowhere for the power to dissipate to and it can result in a fried VTX if you're unlucky.

You can see in the video that the tiny LCD on the VTX is showing 3 horizontal lines in the power output display mode - that means it's sitting there, running 200 mW. For some reason the VTX comes set to 200 mW out of the box - mine was the same. You can just tune it down to 25 mW for the bench testing, then it gets barely hot even just sitting there.
In case you're not sure how to do it - long press the button on the VTX until the three horizontal bars starts flashing on the LCD, then short press to your desired power output setting.

I will change it to 25mw when testing next time.
How about the power supply voltage?5v or 3.3v? Will that also affect the heating?

I was powering mine from the 5V output of the FC. I'm not sure if the 3.3V vs 5V would make a difference in the heating, but I don't think so.

The VTX most likely has voltage regulation on board so it shouldn't matter whether you power it via a 3.3V or a 5V pad from the PDB or FC.

It's not clear how you provided 3.3v to the VTX on the bench because your video only shows you supplying it with 5v, but the only real explanation I can really give is that whatever you were using to supply it with 3.3v maybe couldn't provide enough current to fully power the VTX.

High power output may be the culprit here, but in my case I also had one of those vtx03 heating up way too much. Mine was missing one super small resistor or cap, can't remember. You can compare yours with some manufacturers photos, maybe that is your issue too?

My vtx stopped heating up after I soldered on that part.

In the video I used 5v BEC from an ESC.
I had used LM2596S DC to DC Step Down Adjustable Power Supply Module to provide 3.3V. It says Output current: rated current 2A, maximum 3A

I cut a small piece of heat sink from a bigger one from an old desktop motherboard.
I don't have thermal paste, will it be effective if I just place it on top the chip and use zip tie to hold it?
Should I reduce the length of legs?

I have always powered my VTX-03's (have used them since my first build and still do for lower power applications) with 5vdc and never have had any problems. If I let mine sit at 200mw (max output), all of them will get hot enough to not be able to hold them in my fingers within a minute or so. I always shift them to "pit mode" on the bench before installing. As they are always hardwired into the power, I want to be able to test everything else without burning them out when they are sans antenna.

Electronics are less heat sensitive than our fingers for the most part though and 160 degrees is not actually all that hot to the little board. Once you are move air across it, the heat will dissipate quickly enough. I have only had one burn out and that was because the IPEX connector on the board tore away, effectively leaving the unit without an antenna.

Without thermal paste, you will likely get only marginal results from your heat sync.

(27-Sep-2018, 05:25 PM)kaitylynn Wrote: I have always powered my VTX-03's (have used them since my first build and still do for lower power applications) with 5vdc and never have had any problems.  If I let mine sit at 200mw (max output), all of them will get hot enough to not be able to hold them in my fingers within a minute or so.  I always shift them to "pit mode" on the bench before installing.  As they are always hardwired into the power, I want to be able to test everything else without burning them out when they are sans antenna.

Electronics are less heat sensitive than our fingers for the most part though and 160 degrees is not actually all that hot to the little board.  Once you are move air across it, the heat will dissipate quickly enough.  I have only had one burn out and that was because the IPEX connector on the board tore away, effectively leaving the unit without an antenna.

Without thermal paste, you will likely get only marginal results from your heat sync.

I tested it.
Ran it for 5 minutes continuous in 25mw power. Before heat sink placed temp 145F. After heat sink placed temp 135F.

Tried the vtx on an Airbot Omnibus F4 nano V6 (which is with an LC filter) and then on an Omnibus F4 Pro V2 (clone)
I have recorded a video. Inset is Omnibus F4 Pro V2 (clone). Which has some grains on it.
Any idea how to fix it?



Also,

RSSI is coming always zero (I am using FS-i6 Tx and FS-IA6B Rx)
I had also selected windspeed horizontal and vertical, that is also not showing values.
Channel and Frequency not coming too.