23 februarie 2021

Bandpass VHF and UHF filters

 For the next project (IRIS) I need two small filters, one for VHF and one for UHF. 

The goal is to get rid of the out of band signals.

On modern (especially portable) radios, the front end receiving circuit is not so selective and the received signal to noise ratio is pretty bad, sometime making receiving impossible.

Therefore, wherever is possible, some good, selective passband filters has to be put in place.

The next project has to do with small signals and I must make those filters for VHF and UHF hamradio bands.

Fast and dirty tests looked OK so I made these filters. 

No drawings, just experience :-)

The VHF filters is inspired by a picture found on VE3IUL site.

A nice web page about filters here.

I tested with my IC E92 portable and I could be heard with SLO which, is around 100 mW.

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