Looking at building the GE Double Sideband Junior transmitter
http://n4trb.com/AmateurRadio/GE_HamNews/issues/GE%20Ham%20News%20Vol%2013%20No%202.pdf Why? Because I have all the parts in my junk box except the driver transformer, which is where I'm getting stymied.
Circuit calls for a "driver transformer transformer with a turns ratio of 5.2 to 1, primary to half secondary; and connect the primary as secondary and vice versa. Thordarson 20D97 or equivalent". So not having a driver transformer in my junkbox, I went into the Hammond catalogue.
As the transformers are listed in terms of Primary Impedance to Secondary Impedance; and knowing that Transformers always reflect impedances from one winding to another by the square of the their turns ratio or, expressed as a formula: Zp/Zs = ((Np/Ns)squared); where Zp is primary impedance, Zs is secondary impedance, and Np/Ns is turns ratio; I calculate the two CT primary driver transformers turns ratio as follows:
124D 7K C.T. to 15.8K C.T = turns ratio of 1:1.47
124E 15K C.T. to 33.8K/135K = turns ratio of 1:1.5/1:3
Given that the circuit calls for a 5.2:1 transformer, which as only half of the Secondary is being used I'm really looking for something with a 10.4:1 turns ratio (or flipped around a 1:10.4) the Hammonds wouldn't work as there is not sufficient turns in the Secondary.
Have I got this right? And if correct, where could I source this? 73 Alex