70cm digital input on YT?

What's coming up in the future? Ideas or suggestions welcome.
Post Reply
User avatar
G8NZR
Posts: 64
Joined: Tue Jun 16, 2015 8:17 am
Location: Mirfield

70cm digital input on YT?

Post by G8NZR » Tue Oct 25, 2016 8:18 am

The latest idea/addition may be 70cm digital receive. Analogue video on 70cm is no longer possible, but with the reduced bandwidth of digital signals, you can have digital receive on 437MHz at a symbol rate of 2Ms/s. :o ... Obviously the output would still be on 1316MHz digital.

Several other TV repeaters have this facility, and it may be a useful addition to GB3YT. Again this is a project which would not happen overnight!

Any thoughts anyone :?:

73, Kay
G8NZR

GaryM1EGI
Posts: 30
Joined: Mon Jun 29, 2015 8:55 pm

Re: 70cm digital input on YT?

Post by GaryM1EGI » Sun Nov 06, 2016 3:49 pm

It certainly wouldn't do any harm to have this feature added.
May be more use in terms of DX for people like Rob M0DTS?

Also in the very near future we will be seeing the use of raspberrypi as a common road into DATV, and from what I have seen 70cms will be the most accessible in terms of not requiring a NOV or the need to up-convert to 23cms.

73s Gary M1EGI

G8DKC
Posts: 1
Joined: Tue Nov 08, 2016 10:10 pm

Re: 70cm digital input on YT?

Post by G8DKC » Wed Nov 09, 2016 10:25 am

GB3GV is running the Tutioune Usb Rx in software on 146.5, but after several years of playing with 437Mhz using Hardware and
TT-1600 board in Pc Tutioune Rx, we came down in favour of Hardware.

The modified SUP2400 up converter was found to be very sensitive, early start shows simple DG0VE filter and HabAmp preamp,
this worked well as test, but found GB3LE 70cms Rpt getting in, also GB3CF Tx 3 x 145.6 = 436.8 :-(

Just to finish us off GB3LEU 70cms beacon got in as well, Plus the usual primary user stuff on 70cms.

Bearing in mind voice repeaters and beacons on same site as GB3GV.

Undaunted and with Nigel M1NAS tuning up various filters, we now have...

The big brass one under shelf to knock out most things, including 2 notches for GB3CF x 3, one of the cavities to notch out GB3LE and a pair to remove GB3LEU.

Pictures... https://www.dropbox.com/sh/8n4211w7zr36 ... Bkcva?dl=0


Pew, and it all works with a SSB or Down East Microwave preamp,(not sure if they are doing preamps now?) and Wimo Big Wheel.

I have got in from Edge hill 40 miles south, and during slight lifts signals getting in from Arthur and Steve in Luton area.

Also ran mobile locally.

We are still using the same Sat Rx and SUP2400. You may not have the same problems, remove add filters as necessary :-)

I'm putting up a 19ell beam on 70cms at home, so look forward to getting in to GB3YT.


73

Peter

G8DKC

User avatar
G8NZR
Posts: 64
Joined: Tue Jun 16, 2015 8:17 am
Location: Mirfield

Re: 70cm digital input on YT?

Post by G8NZR » Mon Nov 14, 2016 8:48 am

Hi Peter

Interesting to read what sort of results you have had with various equipment for GV. I've always been a personal fan of dedicated harware rather than software, and I'm just in the process of building version 3 of the repeater controller! This is only because we've gone from one input up to three next year (2 at present), and my originial unit only has 2 max. The controller is all discrete logic - no software involved!

I've also been playing with the SUP2400 and found the same - it does seem quite sensitive on its own, so coupled with a nice pre-amp, we should be good to go on 70 next year - I don't think we'll go down to 2m RB though.

We are also lucky that there is no other TX in the vicinity (for anyone), so we don't have to contend with any interference issues apart from our own TX.

Take-off to the South is not the best I'm afraid, but would like to hear if you have any success with YT. Rob (M0DTS) 100km away can receive the repeater under favourable conditions.

73 Kay

Post Reply