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The erection of the dish on the new pole finally allowed the dish to stay still after adjustment.

Rather amusingly,  Sky News popped up the moment I switched on the system. By sheer coincidence I had aligned the dish perfectly by eye. Getting the UK SB was quite another matter. It needed the dish swinging further East. Then all SB channels immediately became available with reasonable Strength and Quality on the receiver's tuning menu.

Having obtained SQ figures for the IRTE feedhorn I thought I'd better try the new Invacom ADF-120 feedhorn. The problem was a lack of clamping. A search began for suitable raw materials to make a clamping ring. Luckily I found an old Picador 2" V-pulley in cast aluminium.

This I bored out from the original 1/2" to 25mm for a nice sliding fit on the neck of the Invacom feedhorn. Then I turned one side of the pulley to match the IRTE feedhorn's clamping ring. [52mm] Now I could slip the Invacom feedhorn through the newly turned ring and clamp the ring to the IRTE feed boss. The scalar rings were screwed on last. See image alongside.

The change in feedhorns provided an extra 2% on both S&Q. Well worth having! The Invacom feedhorn proved to be rather insensitive to both F/D and focus. I ended up with the feedhorn throat at maximum extension [about 5.5mm] and the scalar rings pressed back against the boss. I then repeated checks for best skew.

I suppose it is possible that the Invacom feedhorn needs a different [more distant] focal point setting compared with the IRTE. Perhaps I should look into this as a potential factor for further gain.

I find it easier to remove the entire feed from the support arms to work on it. This simply involves removing three nuts with a 13mm spanner. A 7mm spanner is very useful when a screwdriver cannot reach the small stainless steel clamping screws for the LNB and feedhorn clamping ring. Swapping feedhorns then becomes a five minute job from start to finish.

It is too soon to say when the UKSB signal will fade. It is only 1.45pm in bright sunshine and clear skies. Many channels were already dropping out by this time when the dish was still hung on the slotted angle stand.

Trying to move the dish when it is clamped to the pole proved the Kathrein mounting was remarkably rigid. Previously I thought the dish itself was flexing. This proved to be an illusion and only the result of the slotted angle members flexing.

I am running just over 30 metres of new coax to a straight connector on the front wall of the house. If I re-route the cable to enter the house from the back I can save ten yards and have no need for the connector. I will wait until I have solid results over a longer period before I decide to cut the new length of cable.

Despite all my efforts so far the UK SB channels started freezing at 17.45pm. Then they began dropping out just before 18.00. By 18.15 there were literally no UK SB channels left. So, still no evening viewing!

Click on any image for an enlargement.

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