Back in 2013, when I was first building my first trial DVB-T TV tuner server, I had decided to cheap out and buy a two port Xiamen Seebest amplifier, max out the gain at 20dB and have that feed a three-way splitter on each port. This should result in a positive gain at each output port, because the signal comes in 20dB high, and is reduced by 4.8dB by splitting loss, and so should still be 15dB above the input counting insertion loss.

Unfortunately, things didn’t quite turn out like this. I’m not sure if it’s because the amplifier had a maximum power output limitation, or the splitters were just utter rubbish, but I was getting only just above noise-floor performance at the tuners, which complained of a 20% signal level. In fact, it was probably both, since direct-from-the-wall, the signal is over 94%, and passing it through one splitter has it down to 35% or thereabouts.

I lived with this for a while, which resulted in unreliable reception, until a sewage flood destroyed the gear. That forced me back to the drawing board, where I arrived at the present powered 8-way splitter which is much more satisfactory.

While digging through my files, I realized I had taken photos of the splitter and torn one apart, hoping to post it online, but I had forgotten.

The Splitter

This particular unit is available on eBay, and is extremely cheap. The unit comes packed with four F-connectors, of a push-over and crimp ring type. It’s not my preferred type of F-connector, but I found that none of my compression F-connectors would mate with the ports on the splitter, due to some threading tolerance it seems.

As a result, I had to create short quad-shield RG6 segments with the supplied connectors in order to use the splitter, but as noted before, performance wasn’t commendable and I don’t recommend you use this device.

The splitter claims a frequency range of 5-1000Mhz, and the packaging seems to imply it’s a directional splitter, but also claims its a coupler, indicating it’s not directional. They must be confused. There aren’t many three-way splitters on the market it seems.

Teardown

Just like the DiSEqC switches, the unit is constructed in a metal shell which acts as the shielding and ground for all the ports. This is covered by a lid with some silicone glue.

A single-sided PCB with solder resist forms the splitter itself. Copious amounts of solder are used to join the centre connectors of each port to the PCB. The shortness of each F-connector’s threading is most apparent in this shot.

Removing the board reveals it is a very thin PCB, and it features two transformers, and is thus a hybrid splitter/combiner. Unless the transformers are very well designed, the performance of the splitter can be poor. However, it can be much better than resistive dividers when it comes to loss of RF power.

Unfortunately, I had no way to properly quantify the performance of the splitter at that time, and now that I do, I no longer possess the splitter itself. Nothing particularly exciting I suppose.

Conclusion

The hybrid transformer style splitter and combiner is the better option when it comes to RF splitting, however, my experience with the Xiamen Seebest products has been rather unsatisfactory. Poor performance and problems with the fit of F-connectors have plagued me, and I no longer use any of their products in my TV tuner server system.

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