1929 Antenna Coupler

built by N1BUG


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This is a very simple "antenna coupler" I built to go with 1929 rigs. A variable condenser in series helps these simple rigs transfer power optimally into a modern antenna. Here I have used a Cardwell .001 mfd (1000 pf) variable condenser. Since 1000 mmfd is not enough for operation on 160 meters with a modern low impedance antenna and the typical antenna coils on 1929 rigs, I have added a Sangamo .001 mfd fixed mica condenser wich can be placed in parallel with the variable condenser by moving one of the clips. A thermocouple type RF ammeter measures current going into the antenna as an aid to adjustment. This somewhat unusual dual range meter is period authentic but would probably not have been available to the builder in 1929. It was made by Jewell for use in a Eastman diathermy machine. Research indicates the machine this meter was used in was patented in 1919. The range (0-1000 miliamperes or 0-4000 milliamperes) can be selected by moving the clip at the back of the meter. The dual ranges of this meter make it usable with rigs putting out anything from a couple of watts to several hundred watts.



Last update January 4, 2022