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Two Tube Doerle
![Two Tube Doerle](images/sparkbench-radio-restoration.jpg)
- This radio uses two #30 tubes and operates on batteries. It has shortwave coverage in two bands, 4.8 to 7.5 MHz and 7.3 to 12.0 MHz using plug in coils
post 07 Jan 2025
Antenna Shortwave Links →
Echelon-Log Beverages
Two Beverages are paralleled a short distance apart, and stepped one in front of the other, can be phased to remove unwanted rearward response
Experimental Short-wave
These circuits perform very well. However, I'm still experimenting
Ferrite coupler
This is a useful device for coupling an external antenna to a radio that has no antenna jack
Flag Pennant Ewe
These antennas work best when propagation time of signals along the horizontal wires matches propagation time of the wave in space around the antenna, and when the earth or a ground system below the antenna is good
Harmonically Related Antenna Broadcast Bands
These two pages describe the assembly and parts measurement of a 1/4 wavelength, end fed receivin
40
Two Beverages are paralleled a short distance apart, and stepped one in front of the other, can be phased to remove unwanted rearward response
These circuits perform very well. However, I'm still experimenting
This is a useful device for coupling an external antenna to a radio that has no antenna jack
These antennas work best when propagation time of signals along the horizontal wires matches propagation time of the wave in space around the antenna, and when the earth or a ground system below the antenna is good
These two pages describe the assembly and parts measurement of a 1/4 wavelength, end fed receivin
![PIC-Keyer](/../antype/ch40/images/pic-keyer.jpg)
PIC-Keyer This project describes the construction of a real "QRP" keyer with a small microcontroller PIC 16F84, with slightly modified hardware also PIC16F62