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Re: [wsjtgroup] 222Mhz Cheaply for WSJT?...sources of transverters

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  • w3sz
    Hello, All, Apropos Anthony s question regarding sources of transverters and my [and others ] positive comments on DownEast Microwave, I thought I d pass along
    Message 1 of 10 , May 8, 2004
      Hello, All,
       
      Apropos Anthony's question regarding sources of transverters and my [and others'] positive comments on DownEast Microwave, I thought I'd pass along this email that appeared on the 'TenTec' list, which I also monitor.  It was sent by a ham in '4land'.
       
      The discussion there revolved around Heil and TenTec quality and service [both considered superb].  The writer thought enough of DEM to cite DownEast as another, stellar example of superb products and service in another sphere of activity [VHF].  Here is that email.  I think it sums up the opinions of those of us who have been lucky enough to own/use DEM equipment"
       
      "Ever notice how the companies with the best products also seem to have the
      best service? I recall once I had trouble with an element and they had a
      tech (that knew what they were doing) walk me thru some checks and
      measurements and then sent a replacement element since they figured I could
      handle soldering to that little pad. They were ready to replace everything
      but I talked them into just the defective part.
      Heil & TenTec. Wonderful companies to do business with. (BTW, for those into
      the VHF & beyond - DEMI is in the same class of great service and
      equipment.)

      my 7.3 centavos worth
      de KD4..."
       
      'Nuff Said.
       
      73 and have a great weekend all,
       
      Roger Rehr
      W3SZ
    • Mike(W5UC) & Kathy(K5MWH) Watson
      At long last I have a pair of 4CX250B s ready to go on the air (the familiar old plumber s delight circuit). The tubes are NOS or have very few hours on
      Message 2 of 10 , May 9, 2004
        At long last I have a pair of 4CX250B's ready to go on the air (the familiar old  "plumber's delight" circuit).  The tubes are NOS or have very few hours on them, but in either case, they are AT LEAST 20 years old.  Should they be burned in before putting HV on them, and if so, how long? 

        Thanks, 73
        Mike, W5UC

        Age and treachery will overcome youth and skill
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      • jim bennett
        I ve been using them for years (40) and have never taken such a precaution. Just be aware that a 250B has a 6.0 volt filament not 6.3. If used on 432 the
        Message 3 of 10 , May 9, 2004
          I've been using them for years  (40) and have never taken such a precaution. Just be aware that a 250B has a 6.0 volt filament not 6.3. If used on 432 the filament voltage should be dropped to 5.0 to 5.5 volts.
           
          Good tube enjoy them
          jim K4KAE
          ----- Original Message -----
          Sent: Sunday, May 09, 2004 9:33 AM
          Subject: [wsjtgroup] 4CX250B's

          At long last I have a pair of 4CX250B's ready to go on the air (the familiar old  "plumber's delight" circuit).  The tubes are NOS or have very few hours on them, but in either case, they are AT LEAST 20 years old.  Should they be burned in before putting HV on them, and if so, how long? 

          Thanks, 73
          Mike, W5UC

          Age and treachery will overcome youth and skill
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        • Bruce Brackin
          Mike - Yes! Filament only at least overnight but 24 hours would be good. Bruce, N5SIX
          Message 4 of 10 , May 9, 2004
            Mike - Yes! Filament only at least overnight but 24 hours would be good.

            Bruce, N5SIX
          • Mike(W5UC) & Kathy(K5MWH) Watson
            We have one Yea, and one nay.. HI. I guess I will take the cautious route and let them cook for 24 hours. Bruce, it s difficult to burn them in with just
            Message 5 of 10 , May 9, 2004
              We have one Yea, and one nay..  HI.  I guess I will take the cautious route and let them cook for 24 hours.  Bruce, it's difficult to burn them in with just the heaters because they are in the amp and the bias supply is running, but I suspect that won't make any difference.  I'm using the well regulated bias supply from the K2RIW 432 amp of many years ago.  For those running 4CX250B's or any of the similar jugs, I can't recommend this biasing scheme enough.  It is simple to build, and the bias is hard regulated which should contribute to the stability of the amp, particularly in the linear modes.  In class C it will keep the bias from creeping up with drive, which would cause the amp to need more than the normal amount of drive to achieve full output.  For those running WSJT I strongly suggest that you investigate running your amp in class C.( don't think this is possible with GG 8877's)  Efficiencies in the 70% or above range can be achieved, thus generating more output with less plate current.
              73
              Mike, W5UC



              At 08:51 AM 5/9/2004 -0500, you wrote:
              Mike - Yes!  Filament only at least overnight but 24 hours would be good.

              Bruce, N5SIX



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            • jim bennett
              Yes, on my 432 and 222 amps I run that bias scheme...excellent. On my old 144 amp I just have it very heavily loaded.....before I learned HI. You can t hurt
              Message 6 of 10 , May 9, 2004
                Yes, on my 432 and 222 amps I run that bias scheme...excellent. On my old 144 amp I just have it very heavily loaded.....before I learned HI.  You can't hurt anything by burning them in, I just never saw anything to be gained by it.....tube was either good or bad....gassy/low emission/burned up screen.....burning it in could not correct any of these.
                 
                have fun
                Jim K4KAE
                ----- Original Message -----
                Sent: Sunday, May 09, 2004 11:44 AM
                Subject: Re: [wsjtgroup] 4CX250B's

                We have one Yea, and one nay..  HI.  I guess I will take the cautious route and let them cook for 24 hours.  Bruce, it's difficult to burn them in with just the heaters because they are in the amp and the bias supply is running, but I suspect that won't make any difference.  I'm using the well regulated bias supply from the K2RIW 432 amp of many years ago.  For those running 4CX250B's or any of the similar jugs, I can't recommend this biasing scheme enough.  It is simple to build, and the bias is hard regulated which should contribute to the stability of the amp, particularly in the linear modes.  In class C it will keep the bias from creeping up with drive, which would cause the amp to need more than the normal amount of drive to achieve full output.  For those running WSJT I strongly suggest that you investigate running your amp in class C.( don't think this is possible with GG 8877's)  Efficiencies in the 70% or above range can be achieved, thus generating more output with less plate current.
                73
                Mike, W5UC



                At 08:51 AM 5/9/2004 -0500, you wrote:
                Mike - Yes!  Filament only at least overnight but 24 hours would be good.

                Bruce, N5SIX



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              • Mike(W5UC) & Kathy(K5MWH) Watson
                Jim, I agree. Bad tubes can t be fixed by burning them in. My experience comes from trying to get a 8877 on 2 mtrs many years ago(early 70 s). They
                Message 7 of 10 , May 9, 2004
                  Jim, I agree.  Bad tubes can't be fixed by burning them in.  My experience comes from trying to get a 8877 on 2 mtrs many years ago(early 70's).  They recommended that even new tubes be burned in.  I had one that arced when I first fired it up.  It  disintegrated the line fuse and sounded like a shotgun in the shack, and needless to say, I had it running down my leg as a result.  Not wanting to experience that again, I'll take the cautious route..  HI.  Hope to see you soon on JT65B EME.

                  Thanks
                  Mike, W5UC

                  At 12:14 PM 5/9/2004 -0400, you wrote:
                  Yes, on my 432 and 222 amps I run that bias scheme...excellent. On my old 144 amp I just have it very heavily loaded.....before I learned HI.  You can't hurt anything by burning them in, I just never saw anything to be gained by it.....tube was either good or bad....gassy/low emission/burned up screen.....burning it in could not correct any of these.
                   
                  have fun
                  Jim K4KAE
                  ----- Original Message -----
                  From: Mike(W5UC) & Kathy(K5MWH) Watson
                  To: wsjtgroup@yahoogroups.com
                  Sent: Sunday, May 09, 2004 11:44 AM
                  Subject: Re: [wsjtgroup] 4CX250B's

                  We have one Yea, and one nay..  HI.  I guess I will take the cautious route and let them cook for 24 hours.  Bruce, it's difficult to burn them in with just the heaters because they are in the amp and the bias supply is running, but I suspect that won't make any difference.  I'm using the well regulated bias supply from the K2RIW 432 amp of many years ago.  For those running 4CX250B's or any of the similar jugs, I can't recommend this biasing scheme enough.  It is simple to build, and the bias is hard regulated which should contribute to the stability of the amp, particularly in the linear modes.  In class C it will keep the bias from creeping up with drive, which would cause the amp to need more than the normal amount of drive to achieve full output.  For those running WSJT I strongly suggest that you investigate running your amp in class C.( don't think this is possible with GG 8877's)  Efficiencies in the 70% or above range can be achieved, thus generating more output with less plate current.
                  73
                  Mike, W5UC





                  At 08:51 AM 5/9/2004 -0500, you wrote:
                  Mike - Yes!  Filament only at least overnight but 24 hours would be good.

                  Bruce, N5SIX



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                • jim bennett
                  Back in the 70 s the cost of an 8877 would have prevented me from putting any voltage on it... HI Always dreamed of having one. Jim K4KAE ... From:
                  Message 8 of 10 , May 9, 2004
                    Back in the 70's the cost of an 8877 would have prevented me from putting any voltage on it... HI       Always dreamed of having one.
                     
                    Jim K4KAE
                     
                     
                    ----- Original Message -----
                    Sent: Sunday, May 09, 2004 12:28 PM
                    Subject: Re: [wsjtgroup] 4CX250B's

                    Jim, I agree.  Bad tubes can't be fixed by burning them in.  My experience comes from trying to get a 8877 on 2 mtrs many years ago(early 70's).  They recommended that even new tubes be burned in.  I had one that arced when I first fired it up.  It  disintegrated the line fuse and sounded like a shotgun in the shack, and needless to say, I had it running down my leg as a result.  Not wanting to experience that again, I'll take the cautious route..  HI.  Hope to see you soon on JT65B EME.

                    Thanks
                    Mike, W5UC

                    At 12:14 PM 5/9/2004 -0400, you wrote:
                    Yes, on my 432 and 222 amps I run that bias scheme...excellent. On my old 144 amp I just have it very heavily loaded.....before I learned HI.  You can't hurt anything by burning them in, I just never saw anything to be gained by it.....tube was either good or bad....gassy/low emission/burned up screen.....burning it in could not correct any of these.
                     
                    have fun
                    Jim K4KAE
                    ----- Original Message -----
                    From: Mike(W5UC) & Kathy(K5MWH) Watson
                    To: wsjtgroup@yahoogroups.com
                    Sent: Sunday, May 09, 2004 11:44 AM
                    Subject: Re: [wsjtgroup] 4CX250B's

                    We have one Yea, and one nay..  HI.  I guess I will take the cautious route and let them cook for 24 hours.  Bruce, it's difficult to burn them in with just the heaters because they are in the amp and the bias supply is running, but I suspect that won't make any difference.  I'm using the well regulated bias supply from the K2RIW 432 amp of many years ago.  For those running 4CX250B's or any of the similar jugs, I can't recommend this biasing scheme enough.  It is simple to build, and the bias is hard regulated which should contribute to the stability of the amp, particularly in the linear modes.  In class C it will keep the bias from creeping up with drive, which would cause the amp to need more than the normal amount of drive to achieve full output.  For those running WSJT I strongly suggest that you investigate running your amp in class C.( don't think this is possible with GG 8877's)  Efficiencies in the 70% or above range can be achieved, thus generating more output with less plate current.
                    73
                    Mike, W5UC





                    At 08:51 AM 5/9/2004 -0500, you wrote:
                    Mike - Yes!  Filament only at least overnight but 24 hours would be good.

                    Bruce, N5SIX



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                  • Mike(W5UC) & Kathy(K5MWH) Watson
                    Me too Jim. This was a tube that I came by at little or no cost, and I think it was worth what I paid for it. I never did get it on the air, and after the
                    Message 9 of 10 , May 9, 2004
                      Me too Jim.  This was a tube that I "came by" at little or no cost, and I think it was worth what I paid for it.  I never did get it on the air, and after the big arcing episode I gave up.  I think if I decide again to go "big gun" on 2 meters, I will try one of the Russian tubes.  I understand they can be had for less than $100.00, and will run full limit output..

                      At 06:29 PM 5/9/2004 -0400, you wrote:
                      Back in the 70's the cost of an 8877 would have prevented me from putting any voltage on it... HI       Always dreamed of having one.
                       
                      Jim K4KAE
                       
                       
                      ----- Original Message -----
                      From: Mike(W5UC) & Kathy(K5MWH) Watson
                      To: wsjtgroup@yahoogroups.com
                      Sent: Sunday, May 09, 2004 12:28 PM
                      Subject: Re: [wsjtgroup] 4CX250B's

                      Jim, I agree.  Bad tubes can't be fixed by burning them in.  My experience comes from trying to get a 8877 on 2 mtrs many years ago(early 70's).  They recommended that even new tubes be burned in.  I had one that arced when I first fired it up.  It  disintegrated the line fuse and sounded like a shotgun in the shack, and needless to say, I had it running down my leg as a result.  Not wanting to experience that again, I'll take the cautious route..  HI.  Hope to see you soon on JT65B EME.

                      Thanks
                      Mike, W5UC

                      At 12:14 PM 5/9/2004 -0400, you wrote:
                      Yes, on my 432 and 222 amps I run that bias scheme...excellent. On my old 144 amp I just have it very heavily loaded.....before I learned HI.  You can't hurt anything by burning them in, I just never saw anything to be gained by it.....tube was either good or bad....gassy/low emission/burned up screen.....burning it in could not correct any of these.
                       
                      have fun
                      Jim K4KAE
                      ----- Original Message -----
                      From: Mike(W5UC) & Kathy(K5MWH) Watson
                      To: wsjtgroup@yahoogroups.com
                      Sent: Sunday, May 09, 2004 11:44 AM
                      Subject: Re: [wsjtgroup] 4CX250B's

                      We have one Yea, and one nay..  HI.  I guess I will take the cautious route and let them cook for 24 hours.  Bruce, it's difficult to burn them in with just the heaters because they are in the amp and the bias supply is running, but I suspect that won't make any difference.  I'm using the well regulated bias supply from the K2RIW 432 amp of many years ago.  For those running 4CX250B's or any of the similar jugs, I can't recommend this biasing scheme enough.  It is simple to build, and the bias is hard regulated which should contribute to the stability of the amp, particularly in the linear modes.  In class C it will keep the bias from creeping up with drive, which would cause the amp to need more than the normal amount of drive to achieve full output.  For those running WSJT I strongly suggest that you investigate running your amp in class C.( don't think this is possible with GG 8877's)  Efficiencies in the 70% or above range can be achieved, thus generating more output with less plate current.
                      73
                      Mike, W5UC









                      At 08:51 AM 5/9/2004 -0500, you wrote:
                      Mike - Yes!  Filament only at least overnight but 24 hours would be good.

                      Bruce, N5SIX



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                    • Walter Miller
                      Mike, Yes, it would be a very good idea to run the tubes with filament voltage only for least a day or two. The purpose is to reactivate the getter inside and
                      Message 10 of 10 , May 9, 2004
                        Mike,
                         
                        Yes, it would be a very good idea to run the tubes with filament voltage only for least a day or two.  The purpose is to reactivate the getter inside and have it mop up residual gas molecules that might contribute to a flashover when HV is finally applied.
                         
                        I did a bit of research on this topic recently when I had to replace the Svetlana GU-74B metal ceramic tubes in an Acom 2000A amplifier.  Acom suggested very strongly that the tubes should be run with filament voltage only for at least 24 hours (in fact they supplied a written procedure that also included gently bringing up the HV after the filament burn-in).  I did the burn-in using a Variac, with the tubes outside the amp on the bench.  I also setup a fan to blow air across the tubes to keep them from overheating. 
                         
                        There is a related comment in the Winter 2004 CQ VHF magazine article titled "Russian Power Tubes in Amateur Radio, part II" (page 73).  Quoting from that article:
                         
                        "Also, in preparing these NOS, old-stock tubes for use it was discovered that the 24 hours of gettering usually considered sufficient often was not enough.  Three to five days was found to be far more effective!"
                         
                        I have also heard comments that the American-made tubes (like your 4CX250B) have better seals and don't need as much attention to the gettering process.  However, I still think it is prudent to give them the treatment anyway.
                         
                        Good luck getting your 2-meter amplifier operational.  One of these days (years?) I will attack the military surplus RF deck with TED designator that has been sitting in my junkbox for a long time.  It originally had a pair of 4X150 tubes, but I plan to install two 4CX250B tubes and run them class C for maximum output on CW and FSK.
                         
                        73,
                         
                        Walt, AJ6T
                        ----- Original Message -----
                        Sent: Sunday, May 09, 2004 1:33 PM
                        Subject: [wsjtgroup] 4CX250B's

                        At long last I have a pair of 4CX250B's ready to go on the air (the familiar old  "plumber's delight" circuit).  The tubes are NOS or have very few hours on them, but in either case, they are AT LEAST 20 years old.  Should they be burned in before putting HV on them, and if so, how long? 

                        Thanks, 73
                        Mike, W5UC

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