Re: DATV on 70MHz.
Posted: Thu Jun 28, 2018 1:30 pm
Grrr - despite saying I wouldn't, I have!
It's amazing what the junk box throws up and I now have 20 watts out on 71MHz from a RA30H0608M module driven by the Portsdown / Express combo - I do wonder how far a barefoot Portsdown at 10mw would go.
On rx I have an upconverter (old 70MHz to 1100MHz unit designed for testing modulators), just needs some gain and a filter - found this which looks nice and easy to build http://pa3csg.hoeplakee.nl/WP/?page_id=62
I even found I had a birdthru line element covering this band!
Just got to sort an aerial - maybe a dipole is a good place to start??
EDIT - just knocked up one of these - http://www.70mhz.org/coaxdipole.htm - seems a reasonable match after some tweaking - not sure how it will work but cost me £5 for the tubing and an hours work so worth a try - but even this is very big!
73 Noel
BTW - for more ideas there's a 71 MHz feature in CQ-TV out this week
It's amazing what the junk box throws up and I now have 20 watts out on 71MHz from a RA30H0608M module driven by the Portsdown / Express combo - I do wonder how far a barefoot Portsdown at 10mw would go.
On rx I have an upconverter (old 70MHz to 1100MHz unit designed for testing modulators), just needs some gain and a filter - found this which looks nice and easy to build http://pa3csg.hoeplakee.nl/WP/?page_id=62
I even found I had a birdthru line element covering this band!
Just got to sort an aerial - maybe a dipole is a good place to start??
EDIT - just knocked up one of these - http://www.70mhz.org/coaxdipole.htm - seems a reasonable match after some tweaking - not sure how it will work but cost me £5 for the tubing and an hours work so worth a try - but even this is very big!
73 Noel
BTW - for more ideas there's a 71 MHz feature in CQ-TV out this week