Elecraft K2 Improving CW Filter
- Here is a cheap and simple way to significantly improve the K2 CW filter(s). With this mod, even strong signals will fade to black as they tune out of the filter pass band
- Android ham radio DX Cluster, compatible with DX Spider, AR-Cluster, DxNet, CC Cluster, and CLX nodes. NKCCluster supports connecting to a user-defined DX cluster node, filtering DX spots per bands of interest
PC Board Filters
- Offer performance comparable to tin-box filters, and except for being bigger, stack up pretty well with those expensive little helical jobs. You just have to be able to make your own PC boards.
Bandpass Filters for Portable Usage
- These are QRP rated 3 Pole Butterworth filters based on a design by K4VX, feature simplicity, almost no insertion loss, and reasonable rejection on the other ham bands.
- Microprocessor based interface designed receives a signal from a Morse key, processes it, and re-transmits it to the radio. A microprocessor in the circuit is pre-programmed with a proprietary algorithm which makes a number of measurements and adjustments to the less percise human generated code.
30 m Band Direct Conversion Receiver
- The direct conversion receiver described consists of only a bandpass filter, mixer IC, VFO and audiofilter. With only 22 parts, this simple circuit should take a few hours at the weekend to construct.