[MrFixr55]

I worked on an 89 a few years ago, definitely not one of my favorite sets. The biggest problem in this set is the "Autodyne" first detector ("Oscillator Mixer" or "Convertor)" stage. Although this type circuit is used in other sets such as the 80, it is particularly troublesome in this set.

Note that there are 2 transformers in the plate circuit of the convertor tube. One is the oscillator transformer, #11 on the diagram. This transformer has 3 coils; the primary in the plate circuit; the secondary having the oscillator tuning; and the "tickler" in the cathode circuit that causes oscillation. The "Primary" of this transformer is in series with the primary of the 1st IF transformer, #15 on the diagram.

First off, ensure that the grid cap wire for the 1st AF tube is within the shield and that the speaker wires are away from both the 1st AF tube and the output tube.

Second, ensue that Cap #17, the AVC filter is correctly installed. It is a 0.09uF cap. You can use a 0.1uF cap. This cap smooths the negative audio signal into a DC component to bias the RF and IF amps. Failure of this cap will cause much funkiness such as motorboating or oscillation.

Third, ensure that all bypass caps are correctly installed, especially those caps that are between the screen grids or the RF and IF tubes and ground. Do not just "bridge" the caps that are i the bakelite bocks or the 4 caps in the metal contai9ner you must remove the old caps from the circuit.

Fourth, remove the grid cap from the IF tube. Does the oscillation stop? If no, troubleshoot this stage and the audio stage.

Fifth, pull the RF amp tube. Any difference?

Sixth, Touch the grid cap of the convertor (1st detector) tube. Does the squealing stop? If so, concentrate on that stage. If not, remove the tube. Does it stop now?

One problem when rewinding the "tickler" of the oscillator is winding it backwards. If so, i believe that you can revere the tickler connections to make it work. Most problems rebuilding this coil will prevent the convertor from correctly oscillating. So, either it oscillates or not.

Unfortunately, neither the Philco diagram nor the Breitman diagram from the Nostalgia Air website have pin diagrams for the coils.

Here is a link to articles from Ron Ramirez (God rest this good man's soul) on the 89.
https://philcoradio.com/library/index.ph...-model-89/

Hope this helps.