Recommend DVB-T USB tuner for VDR (Ubuntu Trust and later Vivid)

Hi,
I just got an antenna mounted at the top of the building for DVB-T reception. I'm even very close to the transmitter tower, and the system was made by a professional, the signal is great!

I'm already running VDR as a backend with a DVB-S2 card for a long time and it is rock solid and stable.
At the moment I have a cheap Chinese off the eBay tuner for DVB-T. Basically it works, no problems at all, except that it uses mcx connection, so an UF to MCX cable needs to be inserted, and I guess I loose a lot of signal strength on that conversion, as it is a thick cable, but I can't confirm that, no ways to test.

The tuner is identified as:

62.955844] DVB: registering new adapter (ITE 9135 Generic)
[   63.038307] af9033 0-0038: firmware version: LINK 3.40.1.0 - OFDM 3.40.1.0
[   63.038325] af9033 0-0038: Afatech AF9033 successfully attached
[   63.038385] usb 1-3: DVB: registering adapter 0 frontend 0 (Afatech AF9033 (DVB-T))...
[   63.081765] it913x 0-001c: ITE IT913X BX successfully attached
[   63.192168] Registered IR keymap rc-it913x-v1
[   63.192709] input: ITE 9135 Generic as /devices/pci0000:00/0000:00:1d.7/usb1/1-3/rc/rc0/input12
[   63.196799] rc0: ITE 9135 Generic as /devices/pci0000:00/0000:00:1d.7/usb1/1-3/rc/rc0
[   63.196834] usb 1-3: dvb_usb_v2: schedule remote query interval to 500 msecs
[   63.196965] usb 1-3: dvb_usb_v2: 'ITE 9135 Generic' successfully initialized and connected
[   63.197130] usbcore: registered new interface driver dvb_usb_af9035

So it is an ITE device, and IT913x bx. I'm on kernel 3.19.0-28-generic #30~14.04.1-Ubuntu, tuner is found without need of media_build.

The only problem I have is with the HD channels, all the SD channels are working excellent. The HD channels are sometimes working good, there are only occasional pixelations on the screen, however, sometimes the video gets corrupted, and it "brakes/falls apart" and becomes green, and garbage on the screen. Switching to SD channel is perfect. After a restart, it usually works. I get full of this in VDR log:

Sep 17 08:48:00 serverpc vdr: [3788] frontend 0/0 lost lock on channel 153 (M1 HD), tp 722
Sep 17 08:48:02 serverpc vdr: [3788] frontend 0/0 timed out while tuning to channel 153 (M1 HD), tp 722
Sep 17 08:48:03 serverpc vdr: [3788] frontend 0/0 regained lock on channel 153 (M1 HD), tp 722
Sep 17 08:48:06 serverpc vdr: [3788] frontend 0/0 lost lock on channel 153 (M1 HD), tp 722
Sep 17 08:48:06 serverpc vdr: [3788] frontend 0/0 regained lock on channel 153 (M1 HD), tp 722
Sep 17 08:48:06 serverpc vdr: [3788] frontend 0/0 lost lock on channel 153 (M1 HD), tp 722

Why could it be, any ideas?

On the other hand, could you recommend me some cheap USB DVB-T (single) tuners that work fine without any problems on Ubuntu kernel 3.19 and onwards, and VDR?
Please list some specific names.

Thanks!

Thanks Wirbel

I'm not using a cheep indoor antenna at all, I have a professional antenna on the top of the building with excellent reception, mounted by a professional. The coax cable goes to my room where the server is, then I need to connect it with the mcx cable.
Not sure if my tuner is the weak spot here, as it is working nice sometimes, and then it starts the lost lock, regained lock and HD DVB-T channels. After a server restart it works fine. I assume it must be the tuner I use. Or?

I will look into the Ganiatech T230, especially if it is a recommended device. I don't see it nowhere except in China stores, any ideas for EU? But first I would like to see if the tuner I have is the problem or something different. Any ideas how to debug this?

I'm 99% sure that the problem is with the cheap stick I have. I already ordered the recommended Ganiatech T230, will take some two or more weeks until I get it, but that should be a fine stick and everything should work as expected.
Once I have it, I will report back here my findings.

Thank you guys for your help!