TDA7492 External Bluetooth Antenna

Hi all. I am looking to install an external antenna on my TDA 7492. Normally, I would just cut the trace and solder a 31.25mm copper wire but this amp will be behind 1/2" oak and some other interference so I need an extended antenna mounted outside my enclosure.

I know will need a ground for the shield of my coax. Will the indicated ground from the datasheet serve as a suitable ground?
 

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@xrk971: Yes, I plan on soldering a U.FL connector in there so I have plenty of antenna options. Ebay is flooded with these, just search "TDA7492P Bluetooth". This is the particular model I have. The temporary switches on the red version have this weird 3rd leg and I cannot figure out how to use external switches (I will be routing my buttons to the top of the box for music controls).

@xrk971: Could you explain what you mean by "set over the resistor on board"? I think I see what you are saying with the GND pin routing through a resistor over the start of the active antenna.

@radiosmuck: Thanks, but having it mounted inside and having a simple looking, clean build are important to me, so I don't want to mount is outside. I've already built the basic frame. Also, the thick oak is really dense and I am losing range in stock configuration.
 

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Did had a look again into this, the CSR8635 is different at this area and this pin is truely GND.

Fitting an u.FL there might work like on the image attached.

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So cutting the board antenne, scratch off the traces silkscreen and some area of the groundplane, solder the u-FL tip and one side of the screen and optional attach a piece of wire to the "spare" pin on the left. Due to the trace is now going 90° to the u.fl, tuning might be needed. the already fittet resistor plus the 2 free 0402 footprints forms a pi-arrangement.
 

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? What's the intent of your post?

If it works for you, does it mean it works for him? Keeping transmitter/receiver close together isn't always possible and getting some range out of a Bluetooth connection should be the goal. :)

Pretty much all enclosures detune an antenna, but ymmv.

Even if they sell thousands of boards, does this mean they are perfectly made? Having an Antenna not at the boards outside isn't something I'd call a good design.
 
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I've bought more bluetooth receivers than I'd like to admit to. Some are definitely better than others, but by and large, they all benefit from an external, vertical dipole antenna mod. The PCB trace antennas are just in a terrible place with respect to optimizing range. So many bluetooth receivers will just drop out at 15 ft or so and it is a major pet peeve of mine so I tend to go a little overboard trying to extend range.

I also just enjoy tinkering and making something cheap that performs on the level of something more expensive.
 

Marcusrs

Member
2014-04-22 11:51 pm
What did you end up doing and what were your results?
I have a similar bluetooth tpa3116 amp on the way, and I would like to extend the range..
If I replaced the printed antenna with a 3cm copper wire pointing upwards, how much would it improve my range - if it would at all? It is - pretty much like yours - going to be encased in 12mm plywood in a halfinator.
 
What did you end up doing and what were your results?
I have a similar bluetooth tpa3116 amp on the way, and I would like to extend the range..
If I replaced the printed antenna with a 3cm copper wire pointing upwards, how much would it improve my range - if it would at all? It is - pretty much like yours - going to be encased in 12mm plywood in a halfinator.

Well after I messed up my previous TPA7492 trying to solder the uFL receptacle, I ended up just not even bothering with the replacement one. I went with a TA2024 amp and this BT receiver. Its a better setup for me in every way, even though it cost me an extra $20. It has the uFL solder pads ready to go so I was able to add the receptacle on there no problem and I just cut the trace to the PCB antenna and added some double sided tape and tin foil to shield the exposed area a little. Additionally, it supports APT-X, has a mic, aux input, and a connection for external control buttons that actually works. Ill try and add a pic or 2