DATV Amplifier ?

Latest News and Discussion about the use of the DATV transponder on Es'hail-2
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DATV Amplifier ?

Post by G1BVI » Sat Jan 08, 2022 3:02 pm

Hi all

For SSB I use a stealth microwave Amplifier which as a clas A Amp draws 8 Amps continuously in transmit.

For DATV I buily an Amp bought on ebay whichafter completion does not produce the expected power.

What I need to do is put a waterproof box in the garden and put a differen amp of higher power >100 W which will be positined under the dish but not a class A amp.

What is out there

Seen nothing coming up on ebay recently.

PE1RKI advertises amps but not the class of opration so I will email him but wondered what others have managed to use.

There are some gret signals on QO100 so they are either huge dishes or big amps.

I only have a 1.1m dish and get a NER at best of 6 on rx

HNY and 73

Nick G1BVI

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Joined: Fri Nov 14, 2014 9:02 pm

Re: DATV Amplifier ?

Post by DG8KD » Sat Jan 08, 2022 6:00 pm

may be worth to contact him:
One of my colleagues at SP wants to sell polishamp with arduino module, his price: 500 E + shipping.
Please inquire on my email sp6gwb@netgate.com.pl
73's de Staszek SP6GWB

This is one of the known polish amps which are used by several members here including me. I am using a 1.2m PFA for Tx.
Have a look at CQ-TV272 page 33 ff.

vy 73

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Re: DATV Amplifier ?

Post by Pa3fbx » Sat Jan 08, 2022 8:11 pm

Hi Nick,
So many hams have so many amps :-) but to help you better you should elaborate what you expect...
1.1 m dish and 80 watts should be sufficiënt for a 333 signal on to the bird. But you really need that 80 watt into the feed and not into heating up cables and connectors..

RKI makes wonderful amps but documents CW power..
DATV you can divide that by 3 times or even 2 if you are pushing the limits...

The amp you made would be my first choice but i'd like some more data.
Currently there are only the 130 Watt UMTS pallets from the polish scapper witch are not expensive and will be great documented in de BATC by jim G7NTG but i suspect it will give a propper 40 to 50 watt DATV So with that 1.1 Dish you need 2 or 4 pieces combined :-)

The best is improving the dish and feed...
keep in mind that every cm cable is loss....
3db is just 20cm dish extra..
1,2 m and 3 turn helical and 40 watt is sufficient to make over power on 333.
but you need 150 Watt to make over power on 1000ks with the same setup..

2 meter dish would be 10 db gain extra solving all power problems but that again who can stock that dish and keep the wife happy...

73es benno, PA3FBX

Posts: 232
Joined: Wed Aug 02, 2017 7:32 am

Re: DATV Amplifier ?

Post by G1BVI » Mon Jan 10, 2022 9:58 am

Thanks all for getting back to me.

I have been trying to improve my receive capability hence the delay in responding.

There are lots of signals on QO100 but I cannot resolve them.

I thought my dish was 1.1 but its only about 1m x 0.9m.
This gives me a max MER of 6 ish on the beacon.

I am going to have to put something bigger up first and might be able to squeeze in a 1.4m although the Gibertini from HiSat seems interesting and has VERY good reviews.
Unfortunately their web site seems to be broken.

WRT the amp
I had already ordered an amp from ebay (polish seller) before Jim sent out his modification info.
If it works I might buy another and combine them.
A complete replan therefore is in order.
A bigger dish
A waterproof box outside to house an amp and remote power switching. and PSU
Mains from house to box
Another Amplifier.
This is not going to happen overnight but I think sort out the dish first.



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Joined: Wed Aug 02, 2017 7:32 am

Re: DATV Amplifier ?

Post by G1BVI » Sun Jan 16, 2022 5:46 pm

As stated in my last post I am upgrading everything.

I am using a Portsdown 4 and so far just transmitted a test card.

Watching other amateurs there are pictures within pictures \and a running stream giving station info.

This uses something called OBS.

What I am struggling to find is an idiots guide on how to do this.

The Portsdown 4 has a camera input and an easycap video input,
It is unclear how to add in these video effects.
It cannot be that hard as many are doing it but I have not located a guide on how to do it?

Can someone point me in the right direction?




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Re: DATV Amplifier ?

Post by G3GJA » Sun Jan 16, 2022 6:27 pm

Contact me vial email: clive@hesh.co.uk I'll talk you through it.



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Re: DATV Amplifier ?

Post by g0mjw » Sun Jan 16, 2022 6:32 pm


OBS is a video mixer application running in Windows, called Open Broadcaster Software. https://obsproject.com/

What you see are images created on PCs and sent to the Portsdown over the network for it to transmit. You can not achieve this with the Portsdown and it's own video inputs. This is similar to but much better than using an easy cap on the output of a video mixer.

So in order to do the same you first need to get to grips with OBS. From there it is relatively simple to send images via Portsdown, either with a transport stream over the network or by capturing a monitor signal with an H264/5 encoder box.


EDIT - Why has this appeared here? I replied to a question above on how to produce video to send via the Portsdown.

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Re: DATV Amplifier ?

Post by Pa3fbx » Tue Jan 18, 2022 9:06 am

Hi, all.

Its here because Nick started a post about amplifiers...

First nick, offset dishes are only measured how wide they are.. so you got a 90cm dish witch is grat for NB but not so great for WB as you found out.
Your upgrading plans sounds great..

@ Mike.. You mentioned an encode H264 to H265 for use of ipts to portsdown.. Should it be able to transmit H265 with portsdown and a pluto?
I was under the impression that portsdown with pluto is limited to h264..
I have used ipts out of OBS directly and also via freestreamencoder but never was able to transmit h265 via portsdown and pluto..

It may be a bit off topic and should be not in this post and i am sorry for that..

73es benno

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Joined: Sat Sep 20, 2014 9:15 am

Re: DATV Amplifier ?

Post by g0mjw » Tue Jan 18, 2022 10:09 am

Benno - quick reply - the latest Portsdown can send whatever transport stream you present it with when used with a Lime Mini. I don't think it would even look inside the transport stream as how the video was encoded, so it could be MPEG2, H264, H265 or even raw data. I and others regularly send H265 using the Portsdown/Lime.

With a Pluto I understand it uses a different interface (RTP?) and that that can only encapsulate H264. However, if you are generating an IPTS on a PC and using a Pluto I don't really understand why a Portsdown would be needed in the loop. I suppose it might be easier to set frequency and power than using the F5OEO Web interface when out portable, but then how would you generate the H265 Transport stream? When using an H264/5 encoder box, with a Portdown and a Pluto it may be limited to H264, but again, the F5OEO Pluto firmware supports an H264/5 encoder box directly, so why add the Portsdown.

If someone were to contribute a package to enable the Portsdown to drive the Pluto via the UDP interface, it ought to be similar to the Lime in capability to send H265. The Portsdown can't generate H265 itself, as far as I know. Maybe the new PI5 will have that capability. Who knows. The Jetson Nano can do it but nobody has produced a convenient portable Portsdown-like interface to it so that solution requires some understanding of Linux on the user side.


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