[P5] New Feedhorn, boss and C120 LNB.

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My new IRTE 0.4 feedhorn, sturdy, triangular support boss and Inverto Black Pro C120 LNB have arrived. Four days from a Sunday afternoon, online order is terrific service from Satellitesuperstore in the uk!

 http://www.satellitesuperstore.com/universal_feedhorn_for_prime_focus_dishes

There is no linear (focus) adjustment on any of these components. So I will have to make any adjustment for best focus using the support arms. I had planned to use short stainless steel screws for cosmetic neatness. Now I will have to introduce some studs (screwed rods) to allow some length adjustment. I can always trim the arms to length and use shorter screws once I have the focus optimised.

 

The clamping ring allows rotation for skew of the LNB. Note that none of the screws have been tightened in these photographs. All the screws are stainless steel to avoid long term rust. Zinc plated fasteners are complete waste of money for outdoor use. Split spring and plain washers are provided to ensure long term security of fastening. While maintaining the ability to rotate the LNB without tools.

Both the feedhorn throat and LNB have a protective plastic film to avoid spider and moisture ingress. An O-ring is trapped in a circular groove in the face between the LNB and feedhorn. The screw should be tightened enough to bring metal to metal contact.

The triangular boss will provide a much neater and more secure fixing of the feed head compared to the original plastic ring and push fit arms.

The whole arrangement is a far more modern and professional looking set-up compared to the original.

View inside the scalar rings of the feedhorn. Overall diameter is 75mm or 3" in old money. The scalar rings are supposed to allow the LNB to see the entire dish without any reduction in true aperture. Nor allowing 'noise' to sneak around the edge of the dish.

I shall make a tubular spacer to support the feedhorn on the centre of the dish. Then I can measure how long the new aluminium arms need to be.

The view inside the Inverto Black Pro [IDLB-SINF01-OOPRO-OPP] LNB throat showing the two small antennae. One for vertical and the other for horizontal polarity. The protective film makes it difficult to capture the fine detail. This image is skewed to avoid reflections from the plastic film. The internal arrangements are concentric to the throat.

The whole LNB is tiny in comparison with many other similar devices. The Inverto Black Pro has a very good reputation on the satellite forums. It's high output and claimed 0.2dB noise level is suitable for high quality, longer cables back to the receiver. Cable lengths of up to 70 metres are claimed to be possible.

This allows considerable freedom of siting of the dish. Not a matter to be lightly dismissed when it comes to a very large dish in the built-up environment. The equally well respected Invacom LNBs are low output and thus limited to much shorter cable runs. It was this factor which tipped me towards the Inverto product.

Click on any image for an enlargement.

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