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Tube purchase gone bad - supplier sending bad tubes?

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  • Lee
    This was originally posted on California Historical Radio Society Yahoo Group 19C8 Tube Posted by: radios4u larrywho@mindspring.com radios4u Mon Jan 31,
    Message 1 of 4 , Feb 1, 2011
      This was originally posted on California Historical Radio Society Yahoo Group

      19C8 Tube
      Posted by: "radios4u" larrywho@... radios4u
      Mon Jan 31, 2011 3:07 pm (PST)

      Hello all:

      I have been working on a Philco radio which uses a 19C8 tube. I have
      never worked with this tube before. It has 3 diodes and a triode in the
      same package. When I tested it, I found the triode section Gm was far
      below the reject point. I ordered 4 of them from Radio Electric Supply.
      This is the company that bought the entire tube inventory from Radio
      Daze. RES claims to check every tube it sells. When my 4 tubes
      arrived, I was pleased to see that they were all from the same
      manufacturer and in the original boxes. Each tube was wrapped in soft
      brown paper. I said to myself that these tubes had to NOS.

      When I tested them, I found that each tube had a bad triode section. I
      could not believe it! Had my tube tester gone bad overnight? Are the
      setting on my tube tester wrong? Is the 19C8 a funny tube that doesn't
      test well?

      I dug out my emissions type tube tester and tested each tube again,
      including the original one from the Philco. They all tested in the red.
      My radio is not ready to run at this time, so I could not do a
      substitution test of one tube for the other. I contacted Radio Electric
      Supply and returned the 4 tubes. As I was repackaging them, I found
      that it was next to impossible to get the soft brown paper back on the
      tubes. Then I realized that Radio Electric Supply had not tested the
      tubes. RES is off my Christmas list for sure.

      Anyone have any experience working with the 19C8 tube?

      Larry
    • KEITH & DEB
      The tubes are probably good but when sitting for so long oxygen poisons the cathode. The cure is to run them for about 12 hrs and retest them You could leave
      Message 2 of 4 , Feb 1, 2011
        The tubes are probably good but when sitting for so long oxygen poisons the cathode. The cure is to run them for about 12 hrs and retest them  You could leave them in your tube tester running for about 12 hrs and then retest them. The oxygen is boiled of the cathode when the heater keeps it hot for a long time. Let me know how this worked- Keith in Victoria
        ----- Original Message -----
        From: Lee
        Sent: Tuesday, February 01, 2011 9:21 PM
        Subject: [VicRadioGroup] Tube purchase gone bad - supplier sending bad tubes?

         

        This was originally posted on California Historical Radio Society Yahoo Group

        19C8 Tube
        Posted by: "radios4u" larrywho@... radios4u
        Mon Jan 31, 2011 3:07 pm (PST)

        Hello all:

        I have been working on a Philco radio which uses a 19C8 tube. I have
        never worked with this tube before. It has 3 diodes and a triode in the
        same package. When I tested it, I found the triode section Gm was far
        below the reject point. I ordered 4 of them from Radio Electric Supply.
        This is the company that bought the entire tube inventory from Radio
        Daze. RES claims to check every tube it sells. When my 4 tubes
        arrived, I was pleased to see that they were all from the same
        manufacturer and in the original boxes. Each tube was wrapped in soft
        brown paper. I said to myself that these tubes had to NOS.

        When I tested them, I found that each tube had a bad triode section. I
        could not believe it! Had my tube tester gone bad overnight? Are the
        setting on my tube tester wrong? Is the 19C8 a funny tube that doesn't
        test well?

        I dug out my emissions type tube tester and tested each tube again,
        including the original one from the Philco. They all tested in the red.
        My radio is not ready to run at this time, so I could not do a
        substitution test of one tube for the other. I contacted Radio Electric
        Supply and returned the 4 tubes. As I was repackaging them, I found
        that it was next to impossible to get the soft brown paper back on the
        tubes. Then I realized that Radio Electric Supply had not tested the
        tubes. RES is off my Christmas list for sure.

        Anyone have any experience working with the 19C8 tube?

        Larry

      • Maurice & Pam
        I think Keith s suggestion just may work. If you could use the tube in an actual powered circuit (where plate voltage is applied) it might even work better -
        Message 3 of 4 , Feb 2, 2011
          I think Keith's suggestion just may work.  If you could use the tube in an actual powered circuit (where plate voltage is applied) it might even work better - to help stimulate electron flow from the cathode.  Most of the readers probably know when vacuum tubes are manufactured and sealed, there is still a minute quantity of gases trapped inside the tube envelope.  A 'getter' compound is placed inside the tube before the sealing process which afterward is heated to high temperature through RF induction to absorb these gases.  The getter also remains active to some degree over the life of the tube to absorb any gases generated by the tube elements during use.  If the tubes have been idle for an extended period, or never used, it seems quite feasible heating the tube by applying filament power for several hours could activate the getter and bring the tube to life.
          Maurice.  (Victoria)
           
          PS - Sorry.  I didn't mean for this to sound like - 'Vacuum Tubes 101'
           
          ----- Original Message -----
          Sent: Tuesday, February 01, 2011 10:20 PM
          Subject: Re: [VicRadioGroup] Tube purchase gone bad - supplier sending bad tubes?

           

          The tubes are probably good but when sitting for so long oxygen poisons the cathode. The cure is to run them for about 12 hrs and retest them  You could leave them in your tube tester running for about 12 hrs and then retest them. The oxygen is boiled of the cathode when the heater keeps it hot for a long time. Let me know how this worked- Keith in Victoria
          ----- Original Message -----
          From: Lee
          Sent: Tuesday, February 01, 2011 9:21 PM
          Subject: [VicRadioGroup] Tube purchase gone bad - supplier sending bad tubes?

           

          This was originally posted on California Historical Radio Society Yahoo Group

          19C8 Tube
          Posted by: "radios4u" larrywho@... radios4u
          Mon Jan 31, 2011 3:07 pm (PST)

          Hello all:

          I have been working on a Philco radio which uses a 19C8 tube. I have
          never worked with this tube before. It has 3 diodes and a triode in the
          same package. When I tested it, I found the triode section Gm was far
          below the reject point. I ordered 4 of them from Radio Electric Supply.
          This is the company that bought the entire tube inventory from Radio
          Daze. RES claims to check every tube it sells. When my 4 tubes
          arrived, I was pleased to see that they were all from the same
          manufacturer and in the original boxes. Each tube was wrapped in soft
          brown paper. I said to myself that these tubes had to NOS.

          When I tested them, I found that each tube had a bad triode section. I
          could not believe it! Had my tube tester gone bad overnight? Are the
          setting on my tube tester wrong? Is the 19C8 a funny tube that doesn't
          test well?

          I dug out my emissions type tube tester and tested each tube again,
          including the original one from the Philco. They all tested in the red.
          My radio is not ready to run at this time, so I could not do a
          substitution test of one tube for the other. I contacted Radio Electric
          Supply and returned the 4 tubes. As I was repackaging them, I found
          that it was next to impossible to get the soft brown paper back on the
          tubes. Then I realized that Radio Electric Supply had not tested the
          tubes. RES is off my Christmas list for sure.

          Anyone have any experience working with the 19C8 tube?

          Larry


          No virus found in this message.
          Checked by AVG - www.avg.com
          Version: 10.0.1204 / Virus Database: 1435/3416 - Release Date: 02/01/11

        • KEITH & DEB
          Hi I just talked to John at Pacific TV and he said it should have plate voltage on it to fix the tube so leaving it in a tube checker wont work. It would
          Message 4 of 4 , Feb 2, 2011
            Hi  I just talked to John at Pacific TV  and he said it should have plate voltage on it to fix the tube so leaving it in a tube checker wont work. It would have to be  in a working ckt for 12 hrs. Keith in Victoria
            ----- Original Message -----
            Sent: Wednesday, February 02, 2011 1:08 AM
            Subject: Re: [VicRadioGroup] Tube purchase gone bad - supplier sending bad tubes?

             

            I think Keith's suggestion just may work.  If you could use the tube in an actual powered circuit (where plate voltage is applied) it might even work better - to help stimulate electron flow from the cathode.  Most of the readers probably know when vacuum tubes are manufactured and sealed, there is still a minute quantity of gases trapped inside the tube envelope.  A 'getter' compound is placed inside the tube before the sealing process which afterward is heated to high temperature through RF induction to absorb these gases.  The getter also remains active to some degree over the life of the tube to absorb any gases generated by the tube elements during use.  If the tubes have been idle for an extended period, or never used, it seems quite feasible heating the tube by applying filament power for several hours could activate the getter and bring the tube to life.
            Maurice.  (Victoria)
             
            PS - Sorry.  I didn't mean for this to sound like - 'Vacuum Tubes 101'
             
            ----- Original Message -----
            Sent: Tuesday, February 01, 2011 10:20 PM
            Subject: Re: [VicRadioGroup] Tube purchase gone bad - supplier sending bad tubes?

             

            The tubes are probably good but when sitting for so long oxygen poisons the cathode. The cure is to run them for about 12 hrs and retest them  You could leave them in your tube tester running for about 12 hrs and then retest them. The oxygen is boiled of the cathode when the heater keeps it hot for a long time. Let me know how this worked- Keith in Victoria
            ----- Original Message -----
            From: Lee
            Sent: Tuesday, February 01, 2011 9:21 PM
            Subject: [VicRadioGroup] Tube purchase gone bad - supplier sending bad tubes?

             

            This was originally posted on California Historical Radio Society Yahoo Group

            19C8 Tube
            Posted by: "radios4u" larrywho@... radios4u
            Mon Jan 31, 2011 3:07 pm (PST)

            Hello all:

            I have been working on a Philco radio which uses a 19C8 tube. I have
            never worked with this tube before. It has 3 diodes and a triode in the
            same package. When I tested it, I found the triode section Gm was far
            below the reject point. I ordered 4 of them from Radio Electric Supply.
            This is the company that bought the entire tube inventory from Radio
            Daze. RES claims to check every tube it sells. When my 4 tubes
            arrived, I was pleased to see that they were all from the same
            manufacturer and in the original boxes. Each tube was wrapped in soft
            brown paper. I said to myself that these tubes had to NOS.

            When I tested them, I found that each tube had a bad triode section. I
            could not believe it! Had my tube tester gone bad overnight? Are the
            setting on my tube tester wrong? Is the 19C8 a funny tube that doesn't
            test well?

            I dug out my emissions type tube tester and tested each tube again,
            including the original one from the Philco. They all tested in the red.
            My radio is not ready to run at this time, so I could not do a
            substitution test of one tube for the other. I contacted Radio Electric
            Supply and returned the 4 tubes. As I was repackaging them, I found
            that it was next to impossible to get the soft brown paper back on the
            tubes. Then I realized that Radio Electric Supply had not tested the
            tubes. RES is off my Christmas list for sure.

            Anyone have any experience working with the 19C8 tube?

            Larry


            No virus found in this message.
            Checked by AVG - www.avg.com
            Version: 10.0.1204 / Virus Database: 1435/3416 - Release Date: 02/01/11

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