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Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Posted: Wed Sep 12, 2018 4:21 pm
by G4GUO
I use an old Sandpiper helical beam for 23 cms, mainly for it's wideband nature, it used to work well into the IOW repeater
until they lost their site. I even worked DL on SSB with 10 watts with it.

- Charles

Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Posted: Wed Sep 12, 2018 8:46 pm
by G0EID
There was also an interesting discussion during the "BATC CAT12 - Antennaes and Baluns that work" presentation.
Posted on BATCOnline YouTube channel.

Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Posted: Thu Sep 13, 2018 1:38 pm
by M5TXJ
My 5.6GHz gear is coming together, a bit of a rats nest but it seems to work ok. Just need an aerial now, where does the best deal guys?
73 Dave.

Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Posted: Fri Sep 14, 2018 4:29 pm
by radiogareth
Me too :-) Are aerials cheaper than 5.8 GHz coax relays??

Gareth
2018-09-14 17.21.11.jpg
2018-09-14 17.21.11.jpg (1.65 MiB) Viewed 826 times

Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Posted: Fri Sep 14, 2018 11:12 pm
by G4EWJ
Gareth,

A 2.4GHz version of the helical would be useful for an Es'hail-2 uplink. Does the material cause any loss? A minimalist version would also save on 'ink'.

Brian

Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Posted: Mon Sep 17, 2018 7:59 am
by radiogareth
I'm going to microwave a sample today and report back. The www is surprisingly vague about the RF properties of PLA.

*** And the great news is that it seems unaffected. 1 minute in a 800 watt microwave with a cup of water, plastic came out stone cold. So it seems suitable for RF....how much of a helical would be good for an uplink? I can search for existing designs or possible do the cad to enable reliable replication. **

Gareth

Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Posted: Tue Sep 18, 2018 11:35 am
by G4EWJ
Sounds good. There'll be some dielectric effect, so the bare minimum of supporting framework would be best.

There's some info here on a helical feed for offset dishes: http://www.g6lvb.com/60cm.htm

Around 5 turns seems to be optimum, but if the framework could support 6 turns, it would allow for experimentation. I wonder if it could be made so that it could attach to the standard 40mm LNB holder?

There's more info here, including a design for prime focus dishes: http://www.w1ghz.org/antbook/conf/Helic ... tennas.pdf

ISS and Es'hail-2 use RHCP, so the helical feed should be left hand to allow for the reflection off the dish face: anti-clockwise when viewed from behind the ground plane.

Brian

Re: ATV on 6cms - It's Cheap and Easy on 5665MHz

Posted: Fri Oct 05, 2018 1:37 pm
by G4EWJ
Weather radar stations on 5.6GHz.

Select Band=C and Country=United Kingdom and click on the dot at the centre of the circle to get the frequency. It might explain some de-sensing if you're near one or beaming at one.

Brian

http://eumetnet.eu/wp-content/themes/ae ... index.html