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Starting work on my 19B - Printable Version

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RE: Starting work on my 19B - jerryhawthorne - 03-22-2014

Jon, congrats on the new grand daughter. That is special! Nice drawing but I'm not smart enough if proper. If wound backwards, you can always reverse the wires going to the lugs. I have a feeling you have done just fine.
Best, Jerry

RE: Starting work on my 19B - Joeztech - 03-22-2014

Jon;

Yes, congratulations on the new grand daughter!
Your drawing has nice detail that others could follow in the future, especially the beginning point and ending point dimensions. You were careful to observe the winding direction, so I think you will be rewarded with correct operation once you get the part back in circuit. Look for negative voltage on the grid of the tube after everything is back in circuit. That does not necessarily guarantee the radio will work, but you will be that much closer to getting it operational again.

Joe

RE: Starting work on my 19B - Mondial - 03-22-2014

Joe, in his radio you will not see any negative grid voltage, as the grid is grounded for DC. The autodyne osc/mixer uses a cathode feedback circuit, and there is no grid resistor to develop negative bias.

[Image: http://www.philcoradio.com/tech/images/89v2_sm.jpg]

RE: Starting work on my 19B - Joeztech - 03-22-2014

Mondial;

OK, I made the response without a schematic to look at. Carry on.

Joe

RE: Starting work on my 19B - PAradiogeek - 03-24-2014

OK I finally got the coil rewound yesterday. Unfortunately, I had to stop immediately after I finished winding the coil and today I spent 13 hours on the road.

After I got home I managed to take a measurement of the DC resistance of the coil. It was around 2.5 ohms. I looked up the resistance per 1K feet of 36 gauge wire and calculated that the resistance should be 3 ohms. I guess that is pretty close, right? I added a coat of laquer to hold the coil in place and called it quits for the night. I will reinstall the coil tomorrow. Fingers crossed!

Jon

RE: Starting work on my 19B - skyscraper - 03-24-2014

2.5k ohms, right?

But yes, that should be close enough.

RE: Starting work on my 19B - PAradiogeek - 03-25-2014

Sky,

I was talking about the DC resistance of the oscillator coil connected to the cathode of the 36 tube. I measured 2.5 ohms and calculated just over 3 ohms. Definitely not 2.5K.

Jon

RE: Starting work on my 19B - morzh - 03-25-2014

RF coils are always in Ohms, definitely not in kOhms. It takes a lot of very thin wire to achieve a kOhm range, like in Shadow Graph coil. RF coils have units, tens or possibly a couple of hundreds turns of not so thin wire. Anywhere from 2 Ohms to 20 Ohms.....

RE: Starting work on my 19B - Radioroslyn - 03-25-2014

As long as you have it wound in the proper direction your all set. Should play like the dickens when you install it
GL
Terry

RE: Starting work on my 19B - PAradiogeek - 03-25-2014

Thanks Terry.

RE: Starting work on my 19B - PAradiogeek - 03-25-2014

SUCCESS!!!!!

I put the oscillator coil back in and connected it up. Then I powered up the radio and within a few seconds I started hearing static. I turned the dial a little ways up to 610 and in came the local sports talk station loud and clear. I still have a little work to do (alignment, and possibly some work will be needed on the shadow meter), but I am thrilled to have this radio playing again. And then of course I have to decide what to do with the cabinet (if anything).

I just listened to an episode of my favorite OTR show "Richard Diamond, Private Detective" on the '19, and it was great.

I want to say a sincere "thank you" to everyone that shared their knowledge or gave their advice. I truly couldn't have done it without you.

Thanks again,
Jon

RE: Starting work on my 19B - skyscraper - 03-26-2014

My apologies, I thought you were talking about the shadow meter coil somehow.. Serves me right for posting after midnight Icon_razz

Congrats on the succesful restoration! This certainly isn't an easy circuit to tame.

RE: Starting work on my 19B - PAradiogeek - 03-30-2014

Hi again,

I have one problem with the radio now, hopefully someone has an idea how to fix it. Sometimes when I turn the volume control the audio starts to oscillate. Does anyone know what might cause that?

I measured the volume pot and it ohmed out at about 850K whereas the schematic says it should be 350K. Could that cause it, or would it be something else?

Thanks in advance.
Jon

RE: Starting work on my 19B - Steve Davis - 03-30-2014

Jon, make sure all three tube shields are in place and are making a good connection to their mounting brackets. Also, check to be sure grid wire to the type 75 tube is routed inside the tube shield.

Steve

RE: Starting work on my 19B - PAradiogeek - 03-30-2014

Steve,

Thanks so much. I didn't have any of the shields in place at the time. I will check that out next time I get a chance. That brings up another question, I only have two of the three shields. Assuming that the shields are interchangeable (are they?), which two tubes should get the shields?

Jon