BATC Forum

Hi folks, please can you help me.
I have been receiving DATV from QO-100 for a while now and would like to get on air with some transmit.
I have a Pluto that I would like to use but I understand that the output is at best 1/2mW and therefore I guess I will need some amplification.
I also am quite a way from the dish so will need to overcome the feeder loss (15m or so).
I am not familiar enough with microwave equipment to know the how to do this.
There a plenty of people showing how they have modified/built high power amps, but a) I never seem to find suitable ones to modify (I did buy one but I afterward found it was an uncommon type that noone knows how to modify, cost me a pretty penny too) and I don't know really what to look for or b) it requires building skills and processes I don't have or have the equipment to carry out.
Can anyone suggest some off the shelf units that I could chain together to get me on the air. I have seen some on ebay (1W at £15, 4W at £36 and 8W at £40) that I think I have seen people chain together to feed the coax.
And finally (no pun intended) I am going to need something with more than 8W output at the dish so what should I be looking for to modify and suggested sources.

I am sure there are other people in a similar situation and are similarly confused who would be grateful of the help.

Thanks for reading this to the end and thanks in advance for any assistance.

Regards
Terry

Depending on what software you intend to drive your Pluto with, you could mount it at the dish with the data over CAT5. A lot cheaper than good coax. Theres a lot of possibilities....
Gareth G4XAT

That's definitely a good idea, however, the low output is still a major issue, so I am still looking for suggestions for amplifiers.
Thanks
Terry

Hi Terry

The real challenge here is generating enough power in the PA.

I would suggest that the way to do this with the minimum expense is to:

• Get the biggest dish that you can.
• Work out how close you can get the PA to the dish. Don't be constrained by buildings - I have my PA in a large waterproof plastic box right next to the dish and feed mains and low level RF to the box.
• Work out the feeder loss and, knowing the size of your dish, you can then work out the PA Power Output that you need.
• You then need to find a suitable PA. This is the hardest, most expensive part as very few are available.
• Only after purchasing the PA should you think about spending money on driver amplifiers.
• Put sufficient amplification with the PA so that you only need to feed it less than 10 mW
• Use cheap satellite coax to feed RF from the shack
• Use enough (cheaper) amplification in the shack to overcome the long feeder loss to the PA

Hope that helps

Dave, G8GKQ

Hi Terry,

Bert Modderman is building power amplifiers for 13cms. You'll be hard pressed to find anything surplus so worth a look, I believe he makes driver amps too. I have some of his kit and it's superb quality.

http://www.pe1rki.com/amplifiers.html

Steve

Thanks Dave, I was already aware of most of this, I already have a 1.1m dish and it is in the clear and I get a reasonable MER with most transmissions from Es'hail. I already have a suitable box ready to go on the back of the mount to house the power amp. This is not where I have the problem.

The question I am trying to get to the bottom of is where can I get amplifiers, what types are suitable without major surgury to modify them and without breaking the bank. Can you use WiFi amps as cable drivers etc. If I go looking for ex commercial high power amps on places like ebay, what should I look for?

I hope that explains things a little better.
Regards
Terry

This popped up elsewhere,

"10 watts for 40-60mW drive @28V. Search eBay for 10W+ RF POWER AMP MODULE "MHPA21010" 2110MHZ-2170MHZ MOTOROLA"

They apparently deliver 10W on 2400, prety handy, data on the www.

Gareth

The MHPA21010 looks interesting but its going to need pcbs and heatsinks, something I am not able to do unfortunately.
Thanks for the idea though.

Hi All

The MHPA 21010 looks good
Has anyone build this allready and checked performance ?

I got my hands on one... so any info would be appreciated

Tnx Jemp, ON7MA

Yes, I have built one, -3dB drive from Pluto gives me about 3 watts DVBS-2.
See my article on page 32 of the latest CQ-TV (273).
Gareth