Unknown manufacturer of a tube type CW practice set. If you know who the manufacturer is or can provide any additional information please me. The single tube used in this set is a 4 prong number 71A with a Lafayette base. The model 71A is a power amplifier Triode tube with low plate resistance which was first introduced in 1926. The set requires 6 volts DC and a set of crystal earphones. The On/Off control which is located in the center of the picture on the left is a rheostat that also controls the tone of the dits and dahs. The six connection points seen at the bottom of the picture on the right are used for an external key, power, and headphones. This practice seems to work as it should as far as I can tell. It is in as found condition except for blowing the dust off. Lafayette practice oscillator???? Homemade??? | 
