I've not tried the AB LNB 01 itself, only the lens, so perhaps I will try it given your test. What was the dish size to achieve the MER that you did ?
Previously I had reduced the Octagon diameter to make a snug fit into the pipe, but the AB LNB 01 has the benefit of plenty of length to play with after cutting off the lens mount.
The AB LNB 01 is a PLL type with a 25MHz crystal. The one that I investigated was not easy to open though, as the sealant had seeped inside to stick tracks to the case, resulting in some pulling-up on opening, although repairable.
Thanks for that info - now, any idea how to get it off the LNB without busting it? The ones above seem to be siliconed on to the LNB - this one seems to be 'snapped on' with a sort of barbed ridge on the inside of the plastic resting behind a small step in the outer diameter of the casting.
I guess I could saw off the w/g and then go to work on the remaining bit of w/g(carefully) with the Dremel?
I'm using a 1.2M channel master and with my Octagon LNB at the optimum position I got an MER of 9 to 9.5dB from the beacon.
With the AB LNB and dual feed it's about 1dB worse but this could be due to the LNB being about 50mm too close to the dish due to the dual feed.
Later this week I'll be installing some longer dish arms like Noel has done and fingers crossed I'll be back around the 9dB mark again.
I've been experimenting myself today with an old 1.2m offset dish that had no feed system whatsoever. Anyway, having built a feed support structure and got everything optimised as far as I could determine, the beacon MER was 9dB, with zero bit errors. The LNB was an Octagon and it used the AB LNB 01 lens on the G0MJW dual band feed. The Rx was a Mk 1 Minitiouner (Sharp type) running version 0.8 software.
The were a couple of factors that I found critical to setting up the feed position. Positioning of the feed at the focus was very important. After having optimised things, I found that the point of the lens cone was positioned at the focal length. With the feed positioned either way, dBs were lost very easily.
The other important point was where on the dish that the feed was pointing. I found this to be optimal just below the centre of the dish, which was confirmed also by the angle of elevation being about right.
Anyway, good luck with your antenna experiments !
Thanks Gareth (and Dave ) - I'll give that a go at weekend.
Be careful not ordering the AB LNB 01 MTwin ! I bought one this week for a nice price from Estonia on eBay, arrived in 4 days! But found it is a DRO version (Nice for the lens if You need it, but not good for QO-100 73 de Frank PH2M
Interesting. As I said previously, I have not tried the LNB as a functional unit, only the lens, which seems to work ok on a couple of dishes. The statement concerning being a 'PLL type' was based on a Single output version that I opened, please see photos below.
- AB LNB 01 Single Obverse.jpg (1.8 MiB) Viewed 617 times
- AB LNB 01 Single Inside.jpg (1.25 MiB) Viewed 617 times