Measuring ICE Bandpass Filter


ICE Bandpass filter with TAPR VNA

Today, I had the possibility to measure the performance of the well known ICE bandpass filters. Read more about the measurement results…

Introduction

A set of bandpass filters are a necessary in a multi signal environment. Almost all contesters have already experienced the problems of signal distortion in a multi transmitter environment. Luckily bandpass filters help us to reduce the interferences between various transmitters.

Today there are bandpass filters available from:

A good construction manual of a 6 / 9 band filter set can be found on the website of the Bavarian Contest Club.

Measurement setup

As usually I used my “poor man’s” Vector Network Analyzer (VNA) from TAPR / Tentec.

In all diagrams S21 (forward transmission) and S11 (reflexion / impedeance matching) were measured. The schematic and the picture below show the measurement setup.

Bandpassfilter - schematic of Measurement

Measurement Setup ICE Bandpass Filter and TAPR VNA

Measured band: 160m (1,8 MHz)

ICE Bandpass filter on 160m with TAPR VNADownload this measurement plot in high resolution: ICE Bandpass Filter 160m

Measured band: 80m (3,5 MHz)

ICE Bandpass filter on 80m with TAPR VNADownload this measurement plot in high resolution: ICE Bandpass Filter 80m

Measured band: 40m (7,0 MHz)

ICE Bandpass filter on 40m with TAPR VNADownload this measurement plot in high resolution: ICE Bandpass Filter 40m

Measured band: 20m (14,0 MHz)

ICE Bandpass filter on 20m with TAPR VNADownload this measurement plot in high resolution: ICE Bandpass Filter 20m

Measured band: 15m (21 MHz)

ICE Bandpass filter on 15m with TAPR VNADownload this measurement plot in high resolution: ICE Bandpass Filter 15m

Measured band: 10m (28 MHz)

ICE Bandpass filter on 10m with TAPR VNADownload this measurement plot in high resolution: ICE Bandpass Filter 10m

Measured band: filters deactivated (transmission loss)

ICE Bandpass filter deactivated with TAPR VNADownload this measurement plot in high resolution: ICE Bandpass Filter deactivated

Conclusions

The filters are well adjusted and perform as expected. Please note that on higher frequencies (15m and 10m) the transmission losses increase. If you don’t really need the filter on this band you should turn it off in order not to waste these 1,5 – 2dB!

About Tobias (DH1TW)

Self-confessed Starbucks addict. Loves to travel around the globe. Enjoys the technical preparations of Amateur-Radio contests as much as the contests themselves. Engineer by nature. Entrepreneur. For more, follow him @DH1TW

Comments

  1. I measured and repaired two of these filters with a miniVNA (now I have a working N2PK VNA, so next time I will be much more accurate) and main problem for these is power: most capacitors (even the ones are included in the unit) are not ready to handle 100w continuously (means RTTY, AM or FM and even long periods of TX under CW or SSB) so you have to be very careful with the combination of power/time/SWR unless you do not care about having to repair it again !!!

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