03-24-2016, 07:07 AM
FYI on the driver transformer. The actual measured ratio on my 37-670 was 2.71(CT) to 1(CT) measured at 400Hz at about 10 volts from my HP 200A audio oscillator. The Hammond 124E would be a great match as it is 3(CT) to 1(CT). It would be connected backward. The dual secondaries would be connected in series aiding (CT in the middle) and used as the primary. The 15K(CT) primary would drive the 6F6 grids. The transformer is large, and can handle 5 watts. I have used it in several restorations and it works great. Another possibility is a Haldorson HVAT-2 universal driver transformer often seen on eBay.
My 37-670 had several broken hair thin wires in the RF front end, likely caused by capacitor replacement. I finally removed the entire unit from the radio, pulled the band switch shaft, and removed each section for inspection and repairs. But I found that I had to reassemble the sections and install the band switch shaft in order to test the coils, since unused coils are shorted out in some of the sections! This would mask any open coils. What a piece of work!
My 37-670 had several broken hair thin wires in the RF front end, likely caused by capacitor replacement. I finally removed the entire unit from the radio, pulled the band switch shaft, and removed each section for inspection and repairs. But I found that I had to reassemble the sections and install the band switch shaft in order to test the coils, since unused coils are shorted out in some of the sections! This would mask any open coils. What a piece of work!
