09 January 2015

Homebrew Attenuator Measurements contd/

Today I characterized another attenuator recently acquired and known as the 'BIG' attenuator on this blog. The performance of this attenuator over the HF frequency band is not as good as the 'copper' attenuator (results shown in the previous blog). The worst case measurement was on one of the 20dB pads at +1.06dB error. Although this unit is solidly constructed, I assume that the fact that it does not have shielded compartments between each attenuator must degrade performance over the frequency range. Perhaps also the switches used are not as good as slide switches for this application.

The shown measurements in fact are optimistic since they do not include insertion loss. I performed separate insertion loss measurements which are shown in the next blog.

As a part of these measurements I also characterized the slope of the Power Meter.

In conclusion, the attenuator certainly is useful for many functions at HF. Also the use of 1/4 Watt resistors will allow use in higher power applications.

The following links

Measured Attenuation

Pi network resistor values and calculations

Slope Calculations

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