I am active as operator at the club station PI4Z and we wanted to take part as a multi single in the major HF contest of the year. To get a high score it is necessary to have a mulitplier station active on another band then the running station. To protect the receivers it is necessary to have good band pass filters.

I already have an ICE419B so I needed another filter. 

I started to look at options to purchase or build these.

I compared several commercial bandpass filters until I found that Bob 5B4AGN has made a design and has organized a group buy for a bandpass filter with builtin BCD band decoder and relay drivers.

The total price of €450 was low compared to the commercial available band passfilters, some of them costs twice that amount. I had to assemble myself of course but if you like building equipment this is an advantage.


The TXbpf like the ICE419 and the 5B4AGN TXBPF have a maximum power rating of 100W, they are used between the transceiver and the amplifier.

Link to the website of Bob 5B4AGN.



In February 2013 another amateur asked me to built the filters.

Link to pictures and measurement data of filter 2.