Review: Oscar’s Backpack VTX (OBVTX)

I am working with AKK on a new VTX – the OBVTX (Oscar’s Backpack VTX). It has some unique features and can be mounted on the back of a micro FPV camera, hence the name “backpack”.

Buyer’s Guide: How to choose VTX?

Update (23 Sep 2018) – Problem with Standoffs

There is an issue with the supplied standoffs – they are too big to fit the Runcam cameras. I brought up the issue with AKK before the official release, but they released it anyway without actually addressing the issue.

I am truly sorry for those who are affected by this problem. I have asked AKK for a solution and how to compensate those who are affected. If you want to buy this VTX and intend to mount it behind the FPV camera, please hold off for now. I will update again when the issue is resolved.

Update (July 2019) – Avoid AKK

AKK removed my name on this VTX quietly, which means they don’t want to give me any credit for the work I’ve done on this VTX.

Also they keep ignoring my request to address the issues with the wrong standoffs provided with the VTX.

What can I say… Avoid them at all cost.

Where to Buy?

The Oscar’s Backpack VTX will be available end of August, you can pre-order it now from AKK.

What’s Special about the OBVTX?

I am always searching for the ideal VTX, there are some really good options on the market, but something is missing. I told AKK about my “ideal VTX” and they decided to make a product based on the features and specs I want.

I have been testing and helping AKK to develop the OBVTX for over 4 months, and I cannot wait to share it with you guys.

The OBVTX is not the first VTX that can be mounted on the back of a camera, but there are something unique about it.

TX200U with fragile IPEX connector

Features and Specs

  • VTX Control using SmartAudio
  • Built-in Mic
  • MMCX Connector
  • 5V Input
  • 25mW and 200mW Switchable Power
  • Pitmode
  • Solder pads
  • 19x19mm
  • 2.8g

The unit I have is just a prototype, it doesn’t reflect the the build quality in the final version.

There are two holes for mounting on the back of a micro FPV camera with screws and 3mm standoffs provided. Because of the tiny form factor, you can also mount it anywhere in the mini quad you see fit :)

The mounting holes are perfectly compatible with Runcam’s cameras, but because Foxeer’s have slightly smaller mounting pattern, you might have to push the standoffs inward to get it to fit. (though I need to verify when I get the final version)

Due to the limited space, AKK is using the same LED indicator design as their Nano2, which I personally find quite confusing when changing settings. But if you are only using SmartAudio it’s not a problem at all.

It has a robust MMCX connector, and a built-in microphone for audio. At first AKK told me it was impossible to fit a Mic in there, but they managed it in the end so kudo to them! We also spent a few weeks on audio quality and it has been improved considerably from the first prototype.

I used the OBVTX when I was testing the Rapidfire, take a look at the performance.

Further Testing

I haven’t even got the production version myself (only prototypes). But I will test this VTX like I normally do when it arrives.

29 thoughts on “Review: Oscar’s Backpack VTX (OBVTX)

  1. Markus

    I use this VTX for a while now. Now I did the first build using BF 4.1.1 and I needed to setup the correct VTX-table. As Jack has asked for it I share it here. But is has just been basically tested so far – but channel-setting and power control seems to work. Just copy them to the CLI and exit with command “save”:

    vtxtable bands 5
    vtxtable channels 8
    vtxtable band 1 BOSCAM_A A FACTORY 5865 5845 5825 5805 5785 5765 5745 5725
    vtxtable band 2 BOSCAM_B B FACTORY 5733 5752 5771 5790 5809 5828 5847 5866
    vtxtable band 3 BOSCAM_E E FACTORY 5705 5685 5665 5645 5885 5905 5925 5945
    vtxtable band 4 FATSHARK F FACTORY 5740 5760 5780 5800 5820 5840 5860 5880
    vtxtable band 5 RACEBAND R FACTORY 5658 5695 5732 5769 5806 5843 5880 5917
    vtxtable powerlevels 2
    vtxtable powervalues 0 1
    vtxtable powerlabels 25 200

    Cheers,
    Markus

    Reply
  2. Jack

    Hi Oscar,

    Love this little vtx and I have three of them. in BF 4.1 we need to definite the vtxtable. I was wondering if you please share the vtxtable for this vtx in particular the power level setting line. Thanks in advance.

    J

    Reply
  3. Julius

    Hi Oscar,
    AKK updated the description in their store: “Dsigned by Oscar Liang, Developed by AKK.”.
    Is it ok to buy again?

    Reply
  4. Scott

    Hi Oscar:

    I thought you might want to know that AKK, being the typical Chinese company, has whored off your design!
    amazon.com/Wolfwhoop-Transmitter-Betaflight-Backpack-Configuration/dp/B07GLJRL6V
    Wolfwhoop now sells your BackPack on Amazon, and for much less than direct from AKK! I hope this shoots them in the f00t! :(

    Scott

    Reply
  5. David FPV

    Hi Oscar,

    I just bought 3 of these. I’d like to 3D print a little mounting bracket for the VTX to be placed in a 20×20 stackk. In order to do so, I’d like to know the exact dimensions of the holes in the PCB.

    I initially measured it with a caliper but my first two prints did not align up. Can you let me know what the exact dimensions are?

    In return I’ll place the bracket on thingiverse.com such that others can benefit from using it.

    Cheers,
    David

    Reply
  6. Forrest

    I bought some new screws/spacers and managed to get my backpack vtx mounted to my camera. I have some extra hardware that I’ll sell at-cost to help someone out- see ebay.com/itm/Mounting-Kit-for-Oscars-Backpack-VTX-and-Runcam-Micro-Cameras/183784554611 (Oscar, I hope it is ok to post this link)

    Reply
  7. Sam

    I’m trying to find some self-tapping screws that will go right through the vtx, then through a spacer and into the camera case. Does anyone know the required screw diameter? I’m thinking they are 1.2mm but I don’t have any calipers to measure…

    Reply
  8. mark w

    Oscar, it’s been months and the standoffs still don’t for Runcam cameras. I bought three, can’t mount them.

    Reply
    1. Oscar Post author

      Exactly why I still recommend against buying them if you plan to mount them behind the camera.
      I’ve asked AKK multiple times, they told me “yes, yes, yes”, but never addressed the issue. I’ve almost given up on them.

      Reply
  9. babi

    I like this vtx a lot, mic is good. Only minor thing is: connector sticks out. And PIT mode cannot be changed via smartaudio it seems.

    Reply
  10. Javier Alonso

    good, also happens to me the same I try to mount it in a runcam micro sparrow pro2 and it does not leave me, I have sent mail to akk to see what solution they propose me, with what they tell me I am telling you, greetings to all. and you are a crack hahaha

    Reply
  11. Tim Ware

    Was there ever a solution to the stand offs? I just bought one from RDQ, and of course the standoff threads are way too big for any micros I have (runcam, caddx, foxeer).

    Reply
    1. Oscar Post author

      I am really sorry, AKK kept promising but I still don’t see a solution. Being thousands of miles away, there is very little i can do apart from warning people on my blog and keep sending them emails…
      Just to be clear, I am not making any money off this product so far.

      Reply
  12. E-Bone

    Hi Oscar,
    This VTX is great; however could you try if you get a chance for a second revision to make one with the connector coming out the bottom or an L connector facing back?
    For pods you cant use the backback because of the height once you attach antenna.
    In order to allow this vtx to fit my builds I just wrapped them in heat shrink and stuff them in the pod, it would be great to secure them to the camera as intended.
    Also is it possible to upgrade the firmware so you dont have to use legacy tbs sa?
    Thanks,
    -E-Bone

    Reply
    1. Oscar Post author

      Thanks for your feedback! It’s not the easiest to work with Chinese manufacturers when it comes to products :) I highly doubt there will be a V2.
      But as for what we have, try to get a right angle adapter/pigtail i think that might fix the problem you have :)
      I don’t get your second point about smartaudio, what’s wrong with it?

      Reply
  13. Ben B

    I bought several of these when I found out about them. Without smart audio connected, is there a way to have it not boot up into pit mode? Mine always starts up with the green power level LED flashing. If I connect to smart audio, go into the config screen and change from race to free and set it, then it will boot on the respective power level e.g. green lit solid for 25mw. I’m running a matek f411 mini with BF 3.5.1 RDQ AKK fix (or something like that). Not sure if the special firmware is even necessary, it just seemed like the right thing to do at the time.

    Reply
      1. babipsylon

        hi Oscar

        betaflight can’t change pit mode, is that correct?

        Nice idea about this 1500 value. I did put these settings in the modes tab. However, even though aux 5 is working properly and betflight shows I can toggle pit mode, I’m under the impression the vtx power does not change. It’s the akk backpack vtx, so it supports PIT mode. I can change the channel trough betaflight osd via smartaudio, so that’s not the issue.. .

    1. wade

      I have an answer. The standoffs see to have a larger diameter thread than those on my foxeer micro preditor. So I couldn’t get it to fit

      Reply
  14. Ched

    Looks good but any chance of it coming with a 90 degree MMCX to sma pigtail. Reason being that the straight one pictured on the sales page will make the pigtail wire stick out of the side of a small quad build.

    Reply
    1. Oscar Post author

      Yes i might play with different MMCX locations. At the moment I prefer to put the antenna directly on the VTX. If I am using a pigtail, I am mounting it inside the frame, not behind the camera.

      Reply

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