Help please

[Paul_01]

Hi

I am new to DATV and have working the basis of a system using a MiniTiouner and modified ADALM-Pluto connected to a PC.
I also have the Portsdown software running on a RPi4.

I would now like to assemble the necessary equipment to put this on the air so I would like some advice.
I do not have any vhf or uhf equipment other than for QO-100 nb. Also my HF equipment is all QRP.

What is the best band to aim for; 70cm,23cm or ? also is there much activity. I am located in IO82PX

Where can I find suitable equipment, amplifiers etc.

Any help would be appreciate.

Paul - M1BKL

[Basil]

If you have the narrow band gear for QO100 why not aim for DATV via that satellite too? What size dish do you have? That and the required feedline length to the dish from the PA will suggest what sort of power PA you need. Analog Devices do a tiny and seemingly very reliable pre amp that will up the Pluto output level enough to drive some PA's.

I am seven miles outside Whitchurch and pretty new to DATV myself, but have a working set up now. I can try and answer any questions, but there are far more able people in here.

All the best Chris 2E0ILY, my direct mail is on QRZ and direct e-mail is fine by me, I can even give you my phone number if you prefer to have a chat.

[G8GKQ]

Hi Paul

Not knowing what the ATV activity is likely to be in your area, it is difficult to know what to recommend. The only certainty is that if you built up a 70cm (or possibly 23cm) portable station, you would probably be able to work some other stations from a decent hilltop near you on activity weekends.

I have 2 other suggestions:

• Try QO-100 DATV. Receive first, and then consider whether you want to invest in a PA for transmit.
• Plan to attend the Midlands Microwave Round Table at Eaton Manor near Church Stretton on 3 December. Although billed as a Microwave event, there will be lots of ATVers, and some located in your area. I'll be there, so do come and chat.

Dave, G8GKQ

[Paul_01]

Hi Chris and Dave

Thanks for your replies and thanks for the information on the Midlands Microwave Round Table meeting.

I have looked at DATV on QO-100 but unfortunately at the moment I only have an 80cm off-set dish.
With this setup I can lock on to the QO-100 beacon signal, but the signal is not sufficient to see any pictures.
My major problem is that because of the orientation of my house I am limited to a max dish size of about 1.0 m.
So I am reluctant to replace the dish unless I know for sure that a 1.0 m dish will work for both rx and tx.

It was for this reason I have been looking at 70cm / 23cm for DATV.

Paul M1BKL

[g0mjw]

I use a 1m dish when at my alternative QTH to TX and RX so I can confirm it will work. It is a bit weak on RX but not that bad. Expect a beacon MER of 7 dB. An 80cm dish should just about lock the beacon. Make sure you have the skew correct as well as the pointing. It is sufficient for 333ks TX with a lot of power (50W) and a high level of FEC 1/4, 1/3, 1/2 etc.

Mike

[M5TXJ]

Hi Paul,

Just to throw something else into the mix, the beacon isn't averse to "throwing a wobbly", I know of amateurs who have thought their system faulty when the beacon is having one of its "moments". Much better to use the wideband monitor to look for activity and try one of the other signals. I think it was yesterday when I noticed the beacon encoder had crashed again.

73 Dave.

[Paul_01]

Hi All

Thanks for all your help, particularly Mike.
I am encouraged by your comments that you can use a 1m dish to the extent that I will look for a 1.0 to 1.2 m dish.
If anyone knows of a source please let me know.
I have looked again at the wideband monitor with my 80cm dish and the software shows carrier and timing locks of between 35 and 40%.
So at least it knows that there is a signal there.

I will still look at building up a 70/23cm system.

Paul m1bkl

[Basil]

Are you intending operating 23cms from home, or portable? I am not sure what or who you could work on 23 cms from Whitchurch. I have a 1.8 meter prime focus, spun aluminium dish on a polar mount I might sell, but it sounds like it might be a bit too big for your situation. I'd concentrate on getting the best and biggest dish you can installed, it means less PA power, less electricity used, (and better RX if you share one dish with both transmission and reception).

Ebay and a satellite UK group, the name of which escapes me right now, are frequent sources of used dishes, but you need to be willing and able to travel to pick them up. As in all over the UK. I think there are still suppliers of decent quality new 1.2 meter dishes, probably offset focus, maybe even the odd new old stock, well respected Gibertini (sp?) ones somewhere lurking.

A 1.2 or even 1.8 meter dish will go on the roof of a car or estate car with STURDY factory roof bars pretty safely if you keep the speed down a bit. With second-hand over 2 meter dishes it becomes a buyer's market as few people have the means of transporting the larger dishes safely, (or even legally).

[g6hfs]

I have just put up an 80cm dish with the bullseye lnb and get good signals at 7db and MER of 2. perhaps a change of lnb may help.

Brian G6HFS

[g0mjw]

I think you mean an MER of 7 an a margin of 2 dB. That's good for an 80cm dish. There looks to be more than enough space for a larger dish though. Nobody will notice it, they will be too busy looking at the tower.

Mike