[MrFixr55]

Hi Bruce, and welcome to the Phorum. I have experienced only one 89 and hope to never experience one again.

So far, I have done 2 Philco 80s, which also use a '36 as an "autodyne" mixer. In the beginning, superhets had a separate local oscillator and a mixer circuit that produced the beat frequency IF signal. Later, the "pentagrid convertor" was developed (2A7, 6A7, 6A8, 6SA7, etc.). In between, the "autodyne" circuit was in use. The issue is getting them to oscillate with stability. The 80 and 89 both use the autodyne circuit, but there are differences between the two, with the 80 being more stable in my limited experience.

Use your signal generator to determine if the mixer is oscillating correctly. In theory, with direct injection into the antenna terminal, you should be able to tune any frequency generated by the signal generator in only one place on the dial, that being the frequency (or close to the frequency) selected on the generator.

Definitely follow the advice given by Terry (Radio Roslyn) and Greg (Nostalgia Radio Time). Almost all coils from early 1930s Philco sets have the primary wound over the secondary with a cellulose insulator between them. Apparently, the cellulose breaks down into a component that is corrosive to copper, corroding the primary till it opens. This is exacerbated by the fact that the primary carries the tubes' plate current in the RF and IF coils. However, in the case of the mixer (1st detector) coil, it is the "tickler" (oscillator feedback) coil that opens. This coil carries all the tube current because it is in the cathode circuit.

If you find the tickler to be open, remove it, remove the celluloid band and inspect the winding underneath it. Ensure that the enamel has not come off the winding below the tickler. Repair if so. Bake the coil in an oven at a low temperature (200 Deg) for a minimum of 30 minutes. Apply a layer of mylar tape that is equivalent to the thickness of the celluloid material previously removed. Wind 25 turns of #39 wire in the same direction as the layer that you removed. Shellac the complete assembly to prevent moisture absorption. More detailed instructions on repairing these coils is found in the Philco Library.

The resistor and capacitor that is in series between this coil and ground should be changed. Replace the 15K Ohm resistor with a value between 8.5K and 10K Ohm. Replace the 700pF cap with a 680 - 700 pF mica or npo ceramic disk cap.

Hopefully this helps. Good luck, keep us posted on your progress and don't hesitate to ask for help!