Antenna switcher and splitter


Jorge Garzón
 

Hi,
I am considering to assembly an antenna switcher and splitter. Did you build yours or buy it from a dealer? I would like to share some beverages with a receiver or two, and also split a signal to share it with two/three rigs.
Any advice welcome!
73

Jorge Garzón Gutiérrez "IberiaDX" 
(EB7EFA · EA1036 SWL · BDXC Member 1409) 
QTH: IN83ag / 43º15' N · 03º56' W
San Roque 95, casa 5 (Villasevil)
39698 Santiurde de Toranzo (ESPAÑA - SPAIN)
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Blog: IberiaDX  · Twitter: @IberiaDX


LA2PJ - Egil
 

Hi Jorge,

I built my own 2-way splitter called "BB-2" in this article:
http://www.dxing.info/equipment/rolling_your_own_bryant.dx

A couple of months later I bought a commercial 5-way splitter (ELAD ASA15).
All signal levels in the homebrew splitter was approximately half an S-unit lower than on the commercial splitter. But with the homebrew unit I'm able to read much weaker signals than I do with the commercial unit. The commercial unit has a built-in amplifier raising the noise floor.

Just one week ago I found this link:
https://www.aliexpress.com/item/4000140516245.html?spm=2114.12057483.detail.3.71be55edpi829d

The price of the chinese unit is is only 25% of what I have to pay here in Norway for the ferrite cores in the homebuilt unit above, so I ordered some of them for experiments. But they'll take another four weeks before arriving here. Looking forward to that.


73
Egil - LA2PJ


Robert Conboy
 

The two transformer ones work better. Transformer 1 is 10 turn autotransformer tapped at turn 7. This transforms 50 Ohms to 25 Ohms. (Or 75 to 37.5). The second transformer is 14 turns center tapped.

The 25 (37.5) Ohm tap from the first transformer goes to the center tap.  The two ports are the outer ends of the second transformer.

Place a 100 Ohm (for 50 Ohm system) or 150 for 75 Ohm system across these two outer ends. This provides the isolation between these two ports.

There is only one ground connection - to the cold side of the first transformer.

Isolation and high frequency response can be improved by cancelling out the self inductance of the transformers by placing a capacitor from the center taps to ground.

For BN-73-202  ferrite cores, I arrived at 330 pF for this capacitor experimentally. See


The splitter I described is like fig. 4.


On Oct 7, 2021, at 5:48 PM, LA2PJ - Egil <egil@...> wrote:

Hi Jorge,

I built my own 2-way splitter called "BB-2" in this article:
http://www.dxing.info/equipment/rolling_your_own_bryant.dx

A couple of months later I bought a commercial 5-way splitter (ELAD ASA15).
All signal levels in the homebrew splitter was approximately half an S-unit lower than on the commercial splitter. But with the homebrew unit I'm able to read much weaker signals than I do with the commercial unit. The commercial unit has a built-in amplifier raising the noise floor.

Just one week ago I found this link:
https://www.aliexpress.com/item/4000140516245.html?spm=2114.12057483.detail.3.71be55edpi829d

The price of the chinese unit is is only 25% of what I have to pay here in Norway for the ferrite cores in the homebuilt unit above, so I ordered some of them for experiments. But they'll take another four weeks before arriving here. Looking forward to that.


73
Egil - LA2PJ







Robert Conboy
 

Anyone building their own, especially antennas, would benefit greatly from getting a NanoVNA and learning how to use it, especially the Smith chart feature. There is a learning curve to operate it, and another learning curve to interpret the measurements, but it’s well worth it, especially for those who don’t have an RF background. Best $60 I ever spent.


vbifyz
 

Here is my design:
https://easyeda.com/3ym3ym/HF-antenna-splitter_copy
It is under CC license, feel free to order PCBs from JLCPCB and build it. I think it is a good beginners project to learn SMD soldering, the parts are not too small.
For MW use, don't fit the HPF parts.

73, Mike AF7KR