Gilat AN8004 mod.

[Zapping]

After a lot of searching I finally managed to find a Gilat AN8004 but I'm having difficulties and I need a little help.

In a first attempt I did an experiment just by removing the waveguide and connecting the cable to RX port but the result was disappointing, I didn't get any results running ODU in all positions.

My location is Spain and I used a 1.35m offset antenna.

Is Gilat sensitive to diseqc?
Do I really have to remove the ODU?
I put the LOF in 20250 MHz with 22KHz on, is this correct?

 

[John]

After a lot of searching I finally managed to find a Gilat AN8004 but I'm having difficulties and I need a little help.

In a first attempt I did an experiment just by removing the waveguide and connecting the cable to RX port but the result was disappointing, I didn't get any results running ODU in all positions.

My location is Spain and I used a 1.35m offset antenna.

Is Gilat sensitive to diseqc?
Do I really have to remove the ODU?
I put the LOF in 20250 MHz with 22KHz on, is this correct?

When i ran my AN8004 i was using a LO 20.050 without 22KHz . The Rx board was taken out and had an sma or F connector fitted for RF out. On mine i fitted a Circ to WR42 transition to the waveguide input and ran it with either the circ poloriser + scalar feed or just the scalar feed.
There is a lot of modding info on the forum showing quite a few different members adapted units .... a forum search should find the topics.

 

[Zapping]

Thanks @John.

I already went through some of the topics about modding on Gilat and supposedly it should only work with removing the waveguide, in fact I got the perception that modding is only done for reasons of reducing weight or adapting a mechanical polarizer and not to improve the reception.

I'm going to try the LO 20050 without the 22KWz, and about diseqc do you know if it has influence?

 

[John]

Thanks @John.

I already went through some of the topics about modding on Gilat and supposedly it should only work with removing the waveguide, in fact I got the perception that modding is only done for reasons of reducing weight or adapting a mechanical polarizer and not to improve the reception.

I'm going to try the LO 20050 without the 22KWz, and about diseqc do you know if it has influence?

Ok, when you say "removing the waveguide," i think you are refering to the circular poloriser - for reception from Ka band D - 16° or 7°East linear Horizontal signals you are correct.
Yes, stripped down to the Rx board only to save weight and less bulky. On my mod with the Circ to WR42 transition adapter for the feed i gained just over 1/2 dB when using it on my 1.2 Gibertini Offset antenna.
Diseqc does not effect the unit.
The overall performance on mine was very good.

 

[moonbase]

Thanks @John.

I already went through some of the topics about modding on Gilat and supposedly it should only work with removing the waveguide, in fact I got the perception that modding is only done for reasons of reducing weight or adapting a mechanical polarizer and not to improve the reception...

'ere is a picture of a Gilat Ka LNB removed from the complete AN8004 unit.
The picture illustrates the point @John was making about stripping the Rx board out and using a WR 42 transition adapter.

.

 

[dreamsat]

I used the original OMT and twisted it out of the aluminum casting

 

[s-band]

Not as nice as deamsat's completed system but here's mine. The OMT was hacked from the ODU body using chop saw (subtle but effective). It's been modified to use an external reference for better frequency accuracy hence the extra cable. The mount fits the ex-Viasat Prodelin 3122 dish.

 

[Zapping]

Bad news, I didn't want to remove the RX part because I don't have the right tools and it could screw everything up but when it didn't work I was forced to open Gilat and got a nasty surprise.

As you can see in pictures, inside is in a terrible state, infiltrations and burned circuits, however the lnb part (I think) seems to be ok.



This is the part that really matters, right?



I've seen that there are several ways to modify Gilat, what's the easiest way to do it for someone who doesn't have a workshop at home?
If you can post more pictures it will help.

 

[dreamsat]

Yep, that's the part that matters. The angled LNB connector is just plugged in and clamped with the aluminum part.

 

[Zapping]

Ok I already have the components separated, now I just have a question...



Can I use the same F socket I removed from ODU, right?
Socket F is for soldering to one of the pins that are on the edge of the lnb?

 

[dreamsat]

I've already done it with this original socket. Clean the solder pin properly and attach it. then fasten with thin screws on the right and left. It is only plugged on and not soldered.

 

[Trust]

I used angled F-conn , its easy to remove the nut .
Also one from circuitboards of moteck diseqc motor , no soldering needed just clamped with long M3 screw

 

[Zapping]

Ok so the socket F connection with board is done through one of the pins like this, right?

 

[dreamsat]

cut off the teflon on the pin. Otherwise it's fine. Note the length of the pin.

 

[jeallen01]

You sometimes have to be "careful" when using angled F-connectors because (at least in some of the cheaper ones) there may be only a "touch connection" from the central female connection from one end to the central connection at the other end => poor connections => signal loss/poor BER!

 

[Zapping]

Update, lnb is not finalized but I already managed to do some tests, my location is not the best for Ka-band, only 7E is received with some quality, tests were done 7E and 16E with a 135cm motorized antenna in cloudy weather.






Notes:
Tbs card 6902 doesn't work for Ka band, I spent a couple of hours without receiving any signal and I only had success when I switched to 6903.
In my location antenna will have to be bigger than yours, 180cm at least.

 

[John]

Update, lnb is not finalized but I already managed to do some tests, my location is not the best for Ka-band, only 7E is received with some quality, tests were done 7E and 16E with a 135cm motorized antenna in cloudy weather.

View attachment 148685 View attachment 148686 View attachment 148677 View attachment 148678


View attachment 148679 View attachment 148680

Notes:
Tbs card 6902 doesn't work for Ka band, I spent a couple of hours without receiving any signal and I only had success when I switched to 6903.
In my location antenna will have to be bigger than yours, 180cm at least.

Well done, your getting there . Ka band tweeking for maximum performance needs a lot of patience - your looking at accuracy settings to one (1) millimetre for focus point settings / lnb pointing angle etc for maximum performance. When i was using my Gilat i slid a section of 40mm OD plastic tube over the feed held rigid by squirting some expanding foam inside to fill the gaps - this will give you more forward / backward positioning option for the focal point of the lnb.

 

[Zapping]

Well done, your getting there . Ka band tweeking for maximum performance needs a lot of patience - your looking at accuracy settings to one (1) millimetre for focus point settings / lnb pointing angle etc for maximum performance. When i was using my Gilat i slid a section of 40mm OD plastic tube over the feed held rigid by squirting some expanding foam inside to fill the gaps - this will give you more forward / backward positioning option for the focal point of the lnb.

Yes you are right, the best focal point is not the one I put in picture, I had to lift the feed a little and secure it with a clamp just for test, however the scan I show is maximum I can get with this dish, a beam coverage here is reduced.

Has anyone tested it on a PF antenna with this scalar feed?

 

[dreamsat]

Yes, but i have only PFA antennas. I made everything myself.

 

[moonbase]

Yes you are right, the best focal point is not the one I put in picture, I had to lift the feed a little and secure it with a clamp just for test, however the scan I show is maximum I can get with this dish, a beam coverage here is reduced.

Has anyone tested it on a PF antenna with this scalar feed?

I am not sure if the waveguide/cone feed that you have attached to the Gilat LNB is optimised for a PF dish?
Originally, the AN8004 unit was designed for an offset dish to the best of my knowledge, I could be wrong on that point though?

I hope it works for you.