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More IF Filter Matching

A project log for BARC 20m QRP Transceiver

A portable 20m QRP transceiver designed and built by the BARC tech night group.

trevor-rh-clarkeTrevor R.H. Clarke 02/23/2022 at 22:240 Comments

A brief update to the IF filter matching. The large different in impedance was making it tricky to get a good match with easy and inexpensive inductors. I had been trying to minimize the number of handmade inductors needed as some people find this a little intimidating and the cost of decent toroids can be a bit high. However I opted for two transformers on type 43 toroids (most like FT50 sized). They each have a 2 turn and 11 turn side which matches to 1512.5Ω. This is something like a 1.08 VSWR which is perfectly acceptable and the windings are pretty low so it should be too hard to make these.

I've pushed the latest schematics to github. Check them out and let me know what you think.

Next up is the receiver audio section, the microphone section, the power amp, and the control circuitry.

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