LNBs for QO-100

Although I have an Octagon with 25MHz reference, injected externally, my second Octagon has a 27MHz reference. It seems to be difficult to obtain a consistent supply of the same type of Octagon

I was keen to try another brand of LNB and having seen that the Goobay 67269 sells on Amazon for £5.43 and uses the NXP chip (guaranteed 25MHz ) TFF1017, I ordered one. On opening it I confirmed it has a 25MHz crystal reference. I haven’t tried it on air yet, but I plan to try it on my smaller, portable ‘Sky’ dish. If successful I will modify it for an external 25MHz (or other frequency) reference input, or maybe one of the SMD TCXOs I bought a while ago!.

The NXP LNB chip should be amenable to a range of reference input frequencies (within reason) opening up the possibility of a 2m or 70cm IF.

Having had success with one Goobay LNB I ordered two more to check out whether it was a repeatable source. The two arrived and were duly opened and checked as both 25MHz reference. They were.

Unfortunately, the Goobay 67269 only has one F socket port, so the possibility of having simultaneous horizontal and vertical polarisation is not possible. Nor can a second port be used for an external reference input. However, the large cavity under the  board, currently used to accommodate the 25MHz crystal, is ideal for mounting a second socket for this purpose.

Sam