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Old 10th Jan 2019, 3:07 pm   #1
Steve G4WCS
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Default Anyone on 70cm ?

looking at putting a mast up with rotatable antennas as this years project.
my station transciever has 70cm capability, and antennas are relatively small.

Was wondering if anyone is on there and has any advice eg

what sort of antenna gain should I be going for ?

Is there any activity on there ?

whats it like for DX ?

Co-ax cable requirement ( 40ft run ) ?

etc

thanks
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Old 10th Jan 2019, 3:26 pm   #2
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Default Re: Anyone on 70cm ?

I guess it depends where you are: round here 70cm is even quieter than 2M! (I'm surrounded by Chalk escarpments to one side and a dense forest to the other). Can't hear any repeaters on either band!

There's *some* working on E-M-E using digital modes (JT44/JT65) I gather - the advantages being that your antennas are relatively small and also can be only a few feet off the ground, and the computer just keeps bashing-away until the other-end responds.

See http://www.ok2kkw.com/next/dj3jj_70cm2010.htm for examples. This is the sort of thing you could easily control using a Raspberry Pi or an old laptop.
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Old 10th Jan 2019, 4:33 pm   #3
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Default Re: Anyone on 70cm ?

I am lucky as I have half a dozen VHF/UHF repeaters within handheld range from me, I can usually get a contact at any time. My interest is in pedestrian portable operation, you have got to love what they put into a weeny HT (handy talkie). Back to the question, it may be fun to access repeaters a long way away (at least you get conformation with the "ping back") and then get to people like me with HTs. 40ft run, RG213 is cheap and good at 430MHz. Otherwise it's down to scheds and just seeing if it can be done.
 
Old 10th Jan 2019, 4:50 pm   #4
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Default Re: Anyone on 70cm ?

For 70cms, it's worth keeping an eye on Willaim Hepburn's Tropospheric forecast...

http://www.dxinfocentre.com/tropo.html

(Choose the 'North West Europe' region using the small drop down box, centre left on the first page).

The higher bands are sometimes even more spectacularly enhanced by good tropo propagation than the VHF bands - but only when the event gets up to and beyond a certain strength.
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Old 10th Jan 2019, 10:29 pm   #5
G4YVM David
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Default Re: Anyone on 70cm ?

Not for me. I like a challenge but.....

2m is as high as I go.
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Old 10th Jan 2019, 10:38 pm   #6
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Default Re: Anyone on 70cm ?

We don't call it 70 Cemetery for no reason around these parts

40ft of RG213 will give you around a 3db loss - not ideal, and if you are going for some form of performance to allow a reasonable chance of working DX, then you need to reduce this as much as is possible.

There are other "flexible" coax cables that give better performance, but you cannot beat Heliax. LDF 4-50 will give about 0.8db loss at that frequency for the same length of run - it is about the largest diameter cable that is still managable.

It is normally picked up at radio rallies for about £1 a metre on the surplus market - connectors are normally around £8 each.

As for antenna gain.....

Well, are we talking a beam, or a vertical?

For any SSB work, a beam is almost essential - really the boom needs to be as long as you can safely manage, and as many elements as possible - Gain is your friend - it will tend to help overcome the feeder losses, by giving you a better budget for loss, it is also reciprocal - both the TX and RX path see the benefit.

If you are just talking a vertical, then as big as you can - again, more Gain is good.

In all cases, height on 70cm is king - the more clear sky your antenna can see the better, if you have local obstructions (hills, high rise buildings etc), these will all either reflect or refract signals on 70cm.

Bigger is always better when it comes to VHF and UHF DXing

Cheers
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Old 10th Jan 2019, 10:53 pm   #7
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Default Re: Anyone on 70cm ?

Just bought a bnib Philips FM1000 to program up for some simplex and repeaters. There are 2 repeaters which I can hear with my scanner with rubber duck, possibly another few with decent aerial.

Had some PMR stuff on 70 years back. Still have a Storno CQP 800, but the battery pack is dud and one of the repeaters I crystalled it for is no longer on air

Thought I would give it a go. I need to put up a new vertical for 2, so I'll get one if those white stick dualbanders Thinking along the lines of the diamond X50. Any other recommendations?

Not interested in SSB on 70 at the moment. I don't think the level activity here justifies more metal in the sky.
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Old 11th Jan 2019, 1:39 am   #8
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Default Re: Anyone on 70cm ?

I spent years on 70cm in the 80's with just 1 watt from a Yaesu FT790 feeding a Tonna 19 ele on the chimney. FM was reasonably busy and even SSB could see several QSO's per day.
Sadly it all tailed off over the years and all I hear now is the odd 'clique' on FM who don't like being interrupted and those dang data bursts. SSB only comes to life during contests.
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Old 11th Jan 2019, 7:40 am   #9
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Default Re: Anyone on 70cm ?

Yep, the community has forgotten the fun to be had on VHF /UHF as they clamour to the exotic HF bands. I wish i had a time machine sometimes...1980 here I come. Tandys, Maplins, VK on a watt and wall to wall 2m!!
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Old 11th Jan 2019, 10:30 am   #10
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Default Re: Anyone on 70cm ?

Extract from archives

"GB3NF - Operational 1981 - 1995
The repeater was switched into operational use at 19:00 hrs on the 4th November …. sharing the bottle of bubbly we had bought along for the occasion." I was there but I have removed all the names for data protection.

It was shut down when the shared mast was removed.

Happy days, I was newly licenced and this was my main window to the radio world with a pair of Pye PF1's on 70 cms. luckily you could whistle the repeater up in those days so long as you got 1750 held in pass band for a second or so. I could also jus receive GB3PH in Portsmouth but needed to focus the signal on the PF1 using a metal bin lid!!! ( later progressed to a Pye PF2 with a portable beam)

Pete

Last edited by G4_Pete; 11th Jan 2019 at 10:32 am. Reason: Typo ""
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Old 16th Jan 2019, 8:50 am   #11
Steve G4WCS
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Default Re: Anyone on 70cm ?

thanks for the replies, Im taken with the idea of the antennas being small enough to set up a few for EME work.

Ive just picked up cheaply a 2 element "Innovantennas" 2 element loop fed yagi for 50MHz, they always look bigger till theyre up in the air, Imagine that back in the days of band 1 TV these sized antennas would have been the norm.
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Old 16th Jan 2019, 10:53 am   #12
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Default Re: Anyone on 70cm ?

It's pretty good here in London 70cm and 2m. I have had a few good QSOs on both. I usually lurk on the top of hills and car parks and only at weekends. There's no dB loss if you get yourself up high.

As yet I haven't even touched a repeater. I need to learn how to use them properly still if I'm honest.
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Old 16th Jan 2019, 8:28 pm   #13
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Default Re: Anyone on 70cm ?

If EME is your aim, then Heliax (as big as you can manage) and antennas (as many and as much gain/decent f/b ratio) as you can manage too.

I know these new fangled datamode things makes EME easier, but actually hearing your own signal return is good fun
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Old 16th Jan 2019, 9:06 pm   #14
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Default Re: Anyone on 70cm ?

This evening, for the first time in weeks, I heard a 70cms QSO via the local repeater. Two men discussing how to heat up a pizza. Mind gripping stuff!
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Old 16th Jan 2019, 9:37 pm   #15
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Default Re: Anyone on 70cm ?

We have a couple of pirates locally who sit on obscure frequencies having discussions that seem to be catalogues of profanities. On one occasion, they were sitting on the output of the Gloucester Hospital repeater. They completely ignore any challenges and unfortunately I have no directional aerials to DF them. So yes, 70cm is in use ;-)
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