OPTICUM LTP 04H Twin LNB

Thomas, which one from Octagon do you use now? 73 Mike

DL1GNM Mike.. there are OPTICUM and OCTRAGON LNBs on the market. Thomas told about his OPTICUM..

Hi, from the local I bought some LSP04H from Globo but I think is Opticum. Now with good 25 MHz reference there very little jumps in frequency. I have not compare it with Octagon.

Yes, I mixed them up. Sorry.

DL1AVX: this one looks really nice. Should be easy to modify to external LO (GPSDO...).

How about cutting the horn and would it fit to 22mm copper tube of POTY?

73 Mike

That is actually done by somebody (don't know his/her call).

When the POTY was simulated/designed (by G0MJW) we discovered that a horn seriously degrades the performance of the S-band part of the POTY (primarily gain (<-- read: illumination of the dish and somewhat axial ratio). Mike then tried another design, a round patch with 'notches'. With this design the patch surface (iirc) could be increased so that the influence of a horn was relatively less, maintaining the necessary S-band gain (<-- read opening angle = illumination of the dish).

So there is a trade off, which is also dependent on the usage. For NB usage the degradation of the S-band part can be (more easily) compensated with increasing power and more gain/SNR with RX (with a (cut off) horn (from a LNB). However, for DATV the uplink link budget is more critical, there every 0.5 dB counts (as I have been told)

Remco, that's why I want always to fit a LNB to the waveguide (22/20mm copper tube). On the NB transponder I get beacon strength with 1-2 Watt key down into my 1.2m dish using POTY feed. This is working well!

But it could be probably optimised a little more I've read here:

POTY S-Band

This would be interesting when operating in DATV using the WB transponder.

73 Mike

DL1GNM Yep, I read that article with @OM6AA's comprehensive analysis of the current patch. Despite the design looks utterly simple you can see the whole thing is sensitive towards a variety of combinatorical factors (factors influencing each other, which are influencing each other, which are etc).

The POTY was NOT designed to squeeze every pB (picobell) out of the performance but after intensive modelling deliberately as a reproducible compromise without needing (complex) metalworking equipment other than metal scissors.

Just opened an OPTICUM LTP 04H from Reichelt like those shown in the Descripton for the new Downconverter. It looks a lot different, e.g. the Crystal is under the PCB. So no "Just open and modify it according to Amsat."

The Chip is not Rafael, it is RDA 3567E, but i cannot find any Datasheet . Anyone?

Crystals under the board are not a problem as long as you can get to their tracks. The Octagon Quad is the same. Leve the crystal in place, cut the track.

My QO-100 Downconverter V3D arrived today. I assembled it and ist works (see picture).

With the LNB, I had no success: I bought an OPTICUM LPT-04H for modification, but it has an other PCB. No quartz ...

So my question: Where can I get the right LNB ?

73, Martin DL9SAD