Success Stories

[F5SWB Dimitri]

Hello everybody,
I have done a light version of the wonderful Portsdown digital transmitter (only 437 Mhz) for now but how is my pleasure to show you the result :
many thanks to all for your help !!!! but the adventure will be continued

[KenW6HHC]

Just an update that I now have all three camera video modes on Portsdown working correctly using my Portsdown/RPi-3/DATV-Express test set-up.
The Pi-CAM and an NTSC home video camera via EasyCAP (BATC VideoDVR unit) all work well.
* Mpeg-2 - video displays correctly
* H264 – now video displays correctly
* EasyCAP – now displays H.264 video correctly


Block Diagram of Portsdown/RPi-3/DATV-Express using either Pi-CAM or EasyCAP or even JPEG file as video source

So a Portsdown newbie can succeed.

Time to start testing audio inputs for Portsdown and creating the extension-cable for my Pi-CAM.

73...de Ken W6HHC

[DG8KD]

Hi Ken,

Good to know that you succeed and everything works.
Regarding the PI camera extension:
I spend a few dollars and bought this:https://www.tindie.com/products/freto/p ... extension/
Good quality and fast delivery

Regards
Rainer

[g0mgx]

Mine is up and running, just waiting for a few bits to finish the PA for 146.5MHz and I am waiting for an enclosure for the touchscreen from a 3D printer to mount it on the case front.

Mark
G0MGX

DSC_0082.JPG (319.85 KiB) Viewed 7228 times

Signal 146.png (25.19 KiB) Viewed 7228 times

[g0mgx]

Hi All,

I've now completed a BPF, LPF and a PGA44 preamp from 'DDK:

http://g0mgx.blogspot.co.uk/2017/06/fil ... lters.html

I can provide build details of the filters if anyone is interested. The PGA144 is a tiny bit low in frequency which I need to address - but I think it will be OK for the time being.

IMG_0261.JPG (82.47 KiB) Viewed 7206 times

Mark
G0MGX

[g8gtz]

Hi Mark

All looks great - it would make a good CQ-TV article

Don't know how I'd missed the PGA144 from Sam, looks just what we need on 146 - I run the DG8 from GM3SEK but is no longer available - I'll update the wiki.

We can put the filter designs on the wiki for all to enjoy.

Noel

[g0mgx]

The filters look pretty good.

all.png (34.14 KiB) Viewed 7196 times

The Yellow is the PGA144 with 20dB attenuation on the tracking generator - so the gain is 20dB. The notch is supposed to be 98MHz but mine is at more like 92MHz so it's all just a little bit "low" but will be OK as-is I think.

The Blue is the BPF and the Purple the LPF.

I'll draw a quick schematic of the filters and post them here.

Mark
G0MGX

[g0mgx]

Filters:

Filters.PNG (35.79 KiB) Viewed 7195 times

[g0mjw]

I have mine nearly working now it is in a case. At the moment, the 2m performance isn't good, I can't demodulate the transmissions. 70cm is better and 23cm good. Performance improves at higher symbol rates. 70cm 333ks has a wide spread in the constellation, so time for trouble shooting. I am concerned the switching PSU I used may be injecting noise onto the power lines.

Incidentally. I had not updated for some time. When I came to test after updating I had a few issues. I used the reset to defaults option and this fixed it.

I will post a picture. We need a better way to mount the touch screen - that has proven the most difficult part of the project. My first screen didn't work properly for touch.

Mike

[G8GKQ]

Mike

Are you using a new Serit tuner? You might want to check that your phase noise problems are not in the receiver first. Put a 10dB pad on the tuner input and see if it improves matters at 70 cm and 146.

Yes, I'm about to need a bezel. Flat to an Aluminium panel. Has anyone on the Forum got a successful 3D print design for this?

Dave