andrews feed horn big dissapointment

I

iwol

Specialist Contributor
Messages
695
My Satellite Setup
channel master 1.2m dish
technomate 6900,,and invacom 0.3 quad lnb
satlook micro
My Location
yorkshire
hi just changed from a standard 40mm maximum lnb to a inverto 1.3 and channel master {andrews] feedhorn, only to find im getting slightly less signal with the feedhorn setup.(big Dissapointment) ive noticed that the members pics on here all have the bracket nearest the lnb ,i needed to put the bracket nearest the feedhorn mouth to get the best signal am i missing something obvious and is there a possibility i may have to adjust the dish very slightly for the feedhorn(please tell me yes) any info advice appreciated p.s. i used to get the 7w sat with slight breakup with the old lnb but it really struggles with the new feedhorn ,i use this as a bench mark cheers guys
 

Attachments

I

iwol

Specialist Contributor
Messages
695
My Satellite Setup
channel master 1.2m dish
technomate 6900,,and invacom 0.3 quad lnb
satlook micro
My Location
yorkshire
picture added
 
ouagadougou

ouagadougou

Regular Member
Messages
74
My Satellite Setup
2m NERA Prime Focus Dish for C/ku Bands, DM500, SkyStar2, Technomate 5500CIP, Force 1122.
My Location
Stockholm & Windhoek Namibia
It looks from the pic like you have a standard 40mm LNB clamp on your dish and this wont necessarily put the new feedhorn phase centre at the focal point of the dish.

You arent guaranteed to get more signal just because you changed to an Andrew feedhorn especially if your original LNB has significantly better performance than the one you have used with the Andrew feed. Performance improvement due to better illumination can be very slight and is best tested with a fringe signal.

Cheers.
 
I

iwol

Specialist Contributor
Messages
695
My Satellite Setup
channel master 1.2m dish
technomate 6900,,and invacom 0.3 quad lnb
satlook micro
My Location
yorkshire
cheers its got a 40 to 20mm adapter which should centralise it wondering if dish may need realighning because of the feedhorn wouldnt imagine the inverto lnb would be any worse than the maximum make i took off
 
ouagadougou

ouagadougou

Regular Member
Messages
74
My Satellite Setup
2m NERA Prime Focus Dish for C/ku Bands, DM500, SkyStar2, Technomate 5500CIP, Force 1122.
My Location
Stockholm & Windhoek Namibia
I dont have a 40mm clamp for my Andrew/CM 1.2m so not 100% sure of the physical difference. You could always measure the focal length with the 40mm clamp and LNBF and then recheck it to make sure the Andrew feed is fitted in the correct place.
 
ouagadougou

ouagadougou

Regular Member
Messages
74
My Satellite Setup
2m NERA Prime Focus Dish for C/ku Bands, DM500, SkyStar2, Technomate 5500CIP, Force 1122.
My Location
Stockholm & Windhoek Namibia
I just compared an Inverto 40mm LNBF and an Andrew/CM feedhorn for my Andrew/CM 1.2m and the Andrew/CM feedhorn needs to be nearer to the dish surface by approximately 5 to 7cm compared to the clamping point on the 40mm Inverto LNBF.

It looks like you are over illuminating the dish with the Andrew/CM feedhorn in a 40mm LNBF clamp.
 
L

Low Profile

Regular Member
Messages
364
My Satellite Setup
DM800HD, DM7000 80GB HD with Asus WL330 wifi + 2GB usb drive, Skystar2.3, 2.2m Kinhuge Dish with Inverto LNB and Invacom ADF-120 feedhorn. Pace 1.3.25 and 80cm for Sky.
My Location
Lot, Dordogne, Correze border.
Is there a ghost signal?
Ie. when the dish moves does the signal go strong, weak, strongest?
If it does then this would tell us that the feedhorn is not directed at the centre of the dish.
 
I

iwol

Specialist Contributor
Messages
695
My Satellite Setup
channel master 1.2m dish
technomate 6900,,and invacom 0.3 quad lnb
satlook micro
My Location
yorkshire
thank oaga i can move the lnb forward about 4cm which puts it in the same spot as other members set up but the signal gets worse any idea thanks
 
I

iwol

Specialist Contributor
Messages
695
My Satellite Setup
channel master 1.2m dish
technomate 6900,,and invacom 0.3 quad lnb
satlook micro
My Location
yorkshire
thanks low profile would that be on all sats or just the weak ones, and how would you overcome this cheers
 
R

Rd100

Guest
First off to start with you do not need to change the lnb clamp as that is the only one andrew do for the dish thats why they supply a spacer you just need to use the 23mm to 40mm spacer that comes in the box with the feedhorn & waveguide and lnb cover,

Next the feedhorn is to far away from dish it should about 2-3cm more to the dish where the three rings are (first ring on its own near the dish and two rings together thats where it should be)


iwol said:
hi just changed from a standard 40mm maximum lnb to a inverto 1.3 and channel master {andrews] feedhorn, only to find im getting slightly less signal with the feedhorn setup.(big Dissapointment) ive noticed that the members pics on here all have the bracket nearest the lnb ,i needed to put the bracket nearest the feedhorn mouth to get the best signal am i missing something obvious and is there a possibility i may have to adjust the dish very slightly for the feedhorn(please tell me yes) any info advice appreciated p.s. i used to get the 7w sat with slight breakup with the old lnb but it really struggles with the new feedhorn ,i use this as a bench mark cheers guys
 
iceman

iceman

Regular Member
Messages
744
My Satellite Setup
3.0m Motorised Channel Master + 4 fixed dish Amstrad_DRX890C
DM7020s,DM800se
UNOHM EP314 PROMAX TV Explorer
My Location
Kyrenia - NORTH CYPRUS
This is what the focal distance looks like on a 1.20 CM dish using the original CM feed
 

Attachments

R

Rd100

Guest
Yes thats right thats what i was talking about, if you are in front of the dish and looking at the lnb holder the first ring on its own faceing the dish thats where thr front of the lnb holder should be,

As in this pic you have posted up that is the same place i alway put the feedhorn and i have installed loads of these dishes and it is the right place,

Also the Andrew & older type channel master feed horn are the same just the andrew feedhorn has a beter feed window as the old channel master one's had a habit of letting in water after a few years

iceman said:
This is what the focal distance looks like on a 1.20 CM dish using the original CM feed
 
I

iwol

Specialist Contributor
Messages
695
My Satellite Setup
channel master 1.2m dish
technomate 6900,,and invacom 0.3 quad lnb
satlook micro
My Location
yorkshire
thanks iceman and rd100 but when i put it where you say the signal is slightly worse the only reason i put it where the pic shows is that the signal was slightly better looks ;like i might try the invacom or put the old maximum back on:( (have i wasted my money) the guinea pig itry it on is 7w and i can check the signal with a digisat meter......thinks seem to make less sense i thought changing the maximum 40mm lnb to the inverto with feedhorn would be better any suggestions explanations appreciated
 
R

Rd100

Guest
Here is the inverto on my dish with the feedhorn, It works fine better then any other c120 or 40mm lnb,

can also be seen in this thread

http://www.satellites.co.uk/php-bin/forum/showthread.php?t=69014

Have you had a move of the dish to see if it all is ok,

Also is the feed horn new as there is diffrent types of ku-band feedhorns for the andrews if so what is the part number on the box



iwol said:
thanks iceman and rd100 but when i put it where you say the signal is slightly worse the only reason i put it where the pic shows is that the signal was slightly better looks ;like i might try the invacom or put the old maximum back on:( (have i wasted my money) the guinea pig itry it on is 7w and i can check the signal with a digisat meter......thinks seem to make less sense i thought changing the maximum 40mm lnb to the inverto with feedhorn would be better any suggestions explanations appreciated
 
I

iwol

Specialist Contributor
Messages
695
My Satellite Setup
channel master 1.2m dish
technomate 6900,,and invacom 0.3 quad lnb
satlook micro
My Location
yorkshire
thanks rd100 yes it was new came in bubble wrap but how can you explain the lower signal when you move the feedhorn where it should be cheers
 
L

Likvid

ASBO Club Member - Persona non grata
Messages
1,752
My Location
Stockholm, Sweden
Did the feed come with separate spacers?

I remember when i installed this dish it came with spacers that had grooves in it so it got exact position.

Also it came with standard spacers with the dish that didn't suit the Andrew feed but only standard 40/60mm LNBFs
 
I

iwol

Specialist Contributor
Messages
695
My Satellite Setup
channel master 1.2m dish
technomate 6900,,and invacom 0.3 quad lnb
satlook micro
My Location
yorkshire
hi likvid it came with spacers that had a groove which will probably match the feedhorn up in a couple of different fixed spacers either where mine is or where members tell me it should be but like i say when i put it where it should be the signal is slightly lower :(
 
R

Rd100

Guest
Like i showed you in the pic just put the feedhorn there and all will be ok,

Like on mine of i move the feedhorn forwards or backwards the signal drops as it is in the correct focal point, If the feedhorn works as it is where it is on your dish there is someting wrong,

What is the model number of the feedhorn it would be printed on the box,

Also did the feedhorn just come in bubble wrap or was it boxed with feedcover and wave guide,



iwol said:
hi likvid it came with spacers that had a groove which will probably match the feedhorn up in a couple of different fixed spacers either where mine is or where members tell me it should be but like i say when i put it where it should be the signal is slightly lower :(
 
I

iwol

Specialist Contributor
Messages
695
My Satellite Setup
channel master 1.2m dish
technomate 6900,,and invacom 0.3 quad lnb
satlook micro
My Location
yorkshire
cheers rd just came in bubble wrap is the will see if no. on feed horn
 
I

iwol

Specialist Contributor
Messages
695
My Satellite Setup
channel master 1.2m dish
technomate 6900,,and invacom 0.3 quad lnb
satlook micro
My Location
yorkshire
hi rd 100 the number on the feedhorn is 3040661 if this means anything
 
Top