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

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M0AYF
Posts: 4
Joined: Sun Feb 07, 2016 2:41 pm

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

Post by M0AYF » Wed Jun 20, 2018 2:05 pm

Thanks Steve,

All understood and thanks for including the nice clear picture of your layout.

73,s

Des (M0AYF)

G4GHD
Posts: 8
Joined: Sun Nov 12, 2017 12:18 am

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

Post by G4GHD » Sat Jun 23, 2018 8:49 am

radiogareth wrote:
Mon Jun 18, 2018 12:09 pm
I know I've missed the activity weekend (business got in the way) but I have an opportunity to operate from Detling Hill next Saturday if anyone has a good path to it. I have a pair of flat plate aerials and a decent surveyors tripod and 2 watts. Just need to wire it all up to 12 volts.
I can have 2M talkback too.
Anyone likely to be around?
Latitude: 51.2983 , Longitude: 0.587641
Grid Reference : TQ 804586, QTH Locator: JO01hh
Thanks
Gareth
I sent you a message but no reply, so not sure if you read it or not, but a path should exist between there and my location:
Longitude : 0.55821 E (0° 33' 30'' E)
Latitude : 51.52406 N (51° 31' 27'' N)
QTH locator : JO01GM

I've explained my rx set up in the message, so not ideal, but, judging by my previous results on 13cm, I reckon I'll be able to see something, despite my low location.

G4HTZ
Posts: 165
Joined: Sat Aug 02, 2014 4:21 pm

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

Post by G4HTZ » Sun Jun 24, 2018 3:50 pm

Hi both
Intresting that there may be some activity in the Kent and Essex
I've just returned from 10 months holiday in Spain , so no 5ghz yet ....I've still got the portsdown , 20w 70cms amp and 70cms beam .....and 70cms pre amp with minitoune RX.

Need to sort a mast out for home qth which is great wakering, 4m east of Southend Essex JO01JN....but portable may be an option .

Cheers
Steve G4HTZ JO01JN
Steve G4HTZ
Great Wakering Essex JO01JN

G4HTZ
Posts: 165
Joined: Sat Aug 02, 2014 4:21 pm

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

Post by G4HTZ » Wed Jul 04, 2018 11:47 am

Looking at daves original posting with the pictures of the grid antenna , I was thinking that the grids look quite far apart ??? Don't really seem spaced close enough for 5.6ghz .....has anyone done any experiments with fitting fine mesh over the reflector/dish grid.

I've just ordered 2 x 27dbi grid dishs for myself and a friend so hopefully will be some activity from the south east of Essex soon .
Steve G4HTZ
Great Wakering Essex JO01JN

radiogareth
Posts: 124
Joined: Wed Jan 06, 2016 9:46 am

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

Post by radiogareth » Sun Jul 29, 2018 5:55 pm

Setting up my gear in the shack, 600mW into one of the 2.5 watt 'linears' into a microwave dummy load. I'm not getting a solid picture in the shack (solid state LCD mini-monitor), am I possibly overloading the poor old RX?

tnx....

g8vpg
Posts: 251
Joined: Fri Oct 11, 2013 9:35 am

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

Post by g8vpg » Mon Jul 30, 2018 1:20 pm

Gareth,
What is wrong with the picture? Is it noisy, rolling, tearing, distorted? Check that both tx and rx are on the same channel. Try the tx alone without the pa. if you feel that overloading is a problem, try reducing the tx power output if it is adjustable or putting some distance between the tx and rx.
73 Shaun.

radiogareth
Posts: 124
Joined: Wed Jan 06, 2016 9:46 am

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

Post by radiogareth » Mon Jul 30, 2018 2:20 pm

Yes, be helpful if I included some more info. I've spent time on it today exploring some possible issues.
Its not being overloaded, just the same if I take to PA off and run the 600mW. in the shack or down the garden.
I have vision buzz at 50 Hz. The picture is lacking horizontal lock, same on two monitors and two different cameras. As far as I can tell both rx & tx are on the same frequency. One is a 8 channel unit RC805 from a few years ago and the TX is a TS5828.
Its almost like its off frequency, but jumping up or down one channel on the TX doesn't help.
TX also gets hot and shuts down,so I have diverted to add a small 5 volt fan on heatsink to that. Its now been on 1/2 an hour and is still transmitting.
This is what I get, mostly without colour.
2018-07-30 14.48.51.jpg
2018-07-30 14.48.51.jpg (392.33 KiB) Viewed 558 times
I've ordered a matched pair (£20 off eBay) as without amy means of checking or adjusting the frequency I'm a bit stuck.

G8GKQ
Site Admin
Posts: 946
Joined: Sun Mar 22, 2009 1:21 pm

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

Post by G8GKQ » Mon Jul 30, 2018 4:41 pm

Looks to me like the video signal is inverted. Possible causes: Receiver is tuned about 15-20 MHz off-channel; or incompatibility between transmitter and receiver. Can you look at the transmitter input and then receiver output on an oscilloscope and see if the sync pulses go up or down?

Dave, G8GKQ

radiogareth
Posts: 124
Joined: Wed Jan 06, 2016 9:46 am

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

Post by radiogareth » Sun Aug 12, 2018 1:52 pm

Well well....bought a NEW rx/tx pair, exactly the same symptoms. Second unit had an on-board mic which made me suspicious as when I whistled, like you do, I got stripes across the screen?? Then I remembered reading somewhere that the chinese leads supplied often didn't follow the yellow for video protocol. Swapped to a chinese lead, bingo, P5 picture and sound.
At least I now have a spare set for rx & tx ;-)
A pair of flat-plate aerials side by side doesn't seem to overload the RX either, but switching of power will be added as I progress.

radiogareth
Posts: 124
Joined: Wed Jan 06, 2016 9:46 am

Anyone tried circular polarization?

Post by radiogareth » Wed Sep 12, 2018 2:52 pm

Lots of designs on 'Thingyverse' for 3-D printed helicals for 5.8.
Easy to build too, yet to be tried on/in any DX.... -3dB at worst on any other polarisation, I think.....

Gareth
2018-09-12 10.40.33.jpg
2018-09-12 10.40.33.jpg (1.39 MiB) Viewed 260 times

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