How to solder new antenna on VTX03?


#1

Hi guys, the antenna on my VTX03 came off in a crash and I couldn’t find it. I realize now what a loose connection it is and I should have used some heat shrink or hot glue to secure it.

So, I don’t want to order another antenna with the connector.
I want to desolder the connector and solder a new antenna on.

BUT, I see this little thing that looks like a diode on the back side of it.
Anybody know what it is?
I’m pretty sure it is going to come off during my soldering so is it going to be a big problem to remove it permanently?
Thanks!!


#2

I first learned of this little guy from @tronaton
Maybe he can explain, in the mean time I’ll look for the thread.


#3

Not sure, but I think it’s a cap - I know of a case where that “thing” had a bad solder joint and the device was sending “all over the place” - it did work - but only for the guy with the bad VTX.

The easy way to remove the SMA from the PCB: Just apply a bit of solder to the whole thing and wait until it “desolders” - this will destroy the SMA connector, but I found it very easy to remove it this way (I don’t want that SMA connector anyways).


#4

I think the little component does some kind of filtering (not an expert on this I read something in a thread) but I have some destroyed VTX03’s so I could give it a try tonight and see how easy it is to remove the connector without removing the little component on the back. I’ll let you know!


#5

you can also solder a new antenna to the back and leave the connector alone.
keep the component there. :wink:


#6

I’m going to do just that! Thanks!


#7

That’s smart @tronaton hehe
I’m still gonna try removing the connector for science (but I forgot it this night…)


#8

I have the new vtx03 and gob soldered a uhl antenna on it, but now reception has some static. I also switched to lemon diversity receiver with longer antenna, maybe interference there? I had almost zero static with the stock whip antenna.


#9

Alright, soldering on a new antenna was a success. I used Kapton tape to secure the cap so it won’t come off if my iron slipped or I heated the joint for too long.


#10

Hi There,

I’m trying to perform the same with my Vtx02. If I check continuity between signal and ground I get short. Is that normal due to the little cap\diode?


#11

What kind of antenna? Cloverleaf antennas are electrically connected between signal and ground so they always read as a short, dipoles are not (the one we use anyway).


#12

Thanks for the reply. I’m using a Dipole(Whip) and the short actually is measure at the point of the signal output and GND (Where the diode\cap\resistor is - Look at the above image)


#13

Took me forever, but I finally had a moment to measure a vtx03. The signal pad does have a very low ohm connection to the ground pad on a brand new in box unit I just received.


#14

Yeah that caps for impedance matching.