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Model 89 bakelite block clarification - Printable Version

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Model 89 bakelite block clarification - NostalgiaRadioTime - 02-16-2014

Since my model 89 has the K-21 speaker, but still has the #36 tube, I've determined my set is somewhere between schematics #6, #7, and #8 in the http://www.philcoradio.com/tech/89evol.htm section. My question concerns the change made between November 15, 1933: Code 123, Run 7 and December 1, 1933: Code 123, Run 9 :

"Condenser 3615-L, .05 uF, formerly in parallel with .09 uF section of condenser ( 8 ), removed. Condenser (5), 4989-AG (.09 uF with 300 ohm resistor) removed. Above three parts replaced by condenser 4989-H (twin .09 uF) and flexible resistor 33-3010 (300 ohms) added from cathode of RF socket and ground."

My # 44 RF tube has what looks like a little cloth covered worm between the cathode to ground. I'm assuming that is the flexible resistor 33-3010 (300 ohms) mentioned above? Mine reads open so I can't verify the value.

Code 123, Run 7 looks like this:
   

And Code 123, Run 9 looks like this:
   

For the bakelite block shown as #5 in Run 7, and as 5 and 5a in Run 9, if I'm reading that right, having that little cloth covered flexible resistor replaces having a 300 ohm resistor and the .09 mfd capacitor inside the bakelite block? In other words, should there just be a .09 mfd cap in the block, and that separate 300 ohm resistor outside the block, mounted from the cathode of the #44 tube to ground?

My theory for this is the separate designation on the bakelite block on Run 7 of the . 09 mfd cap & 300 ohm resistor as being just #5, and on Run 9 it became #5 for the cap, and #5a for the resistor.

Any thoughts, ideas, whacks along side the head would be most helpful Icon_smile

RE: Model 89 bakelite block clarification - tab10672 - 02-16-2014

Look on top of the block at the lugs you can see where the wire from whatever is inside comes up through the hole at the mounting eyelet and solders to the lug. Is there something soldered to all 3 lugs or just 2 (not wires coming to the block, the small bare wire going down into the block at the back of the lug)

RE: Model 89 bakelite block clarification - tab10672 - 02-16-2014

If something soldered to all 3 there is more than 1 component inside.

RE: Model 89 bakelite block clarification - tab10672 - 02-16-2014

When its part # plus an A or B they are usually together

RE: Model 89 bakelite block clarification - NostalgiaRadioTime - 02-16-2014

Thanks! Yes, there were two components in the block when I restuffed it, so I did put the cap and resistor back in. I was just trying to figure out what that little cloth covered resistor looking thing is and if it needs to be there at all (and what to replace it with). That's what made me think, looking at the changes between the two versions, that maybe one or the other resistor was eliminated, as I can't find that little cloth covered "flexible" one on the schematic. Anyhow, I'm grateful to Ron for pointing out all of the many changes to the 89's that took place during their run on the page he created. Without that, it would almost impossible to figure out what's what!

RE: Model 89 bakelite block clarification - tab10672 - 02-16-2014

Code 123 run 9 looks like the block was changed to a twin .09 and the flex 300 ohm added seperate.

RE: Model 89 bakelite block clarification - tab10672 - 02-16-2014

What was in the block when you removed the inside? 2 paper/foil caps or 1 cap and a folded length of wire?

RE: Model 89 bakelite block clarification - tab10672 - 02-16-2014

As far as what to replace the flexible resistor with, I think the wire wound was more for precision. I have used a flame proof 2% tol.

RE: Model 89 bakelite block clarification - NostalgiaRadioTime - 02-16-2014

Actually, it may have been two of those flat foil caps in the block now that I think of it. There's a light-bulb-going-on moment! Me thinks it's time to open that block up again and add a second . 09 mfd cap in place of the resistor previously installed.