[Amps] Dentron 160-10L 10 meter issue

[Carl]

All the 2-4 tube 811A/572B amps are touchy on 10M due to the high value of the Tune caps. Dentron warns to not go below 5 on the Load cap.

Id start there and in the CW position and tune for maximum smoke.

Carl

  ----- Original Message ----- 
  From: Tim Kass 
  To: amps at contesting.com ; Carl 
  Sent: Thursday, September 06, 2012 9:23 PM
  Subject: Re: [Amps] Dentron 160-10L 10 meter issue


        Well, it wasn't a trap or a jumper, seems that the TUNE control on this amp is WAY sensitive..move it a bit and the SWR went to Zero..anyone have this experience?  Is this characteristic of this amp or did the upgrade from 811A's to 572B's change the impedance.. the tube are Shuguang tubes..good output, talking on 20 meters SSB and no color on the tubes.. runs about 750 watts key down..

        73, Tim K8WBL

        --- On Thu, 9/6/12, Tim Kass <k8wbl at yahoo.com> wrote:


          From: Tim Kass <k8wbl at yahoo.com>
          Subject: Re: [Amps] Dentron 160-10L 10 meter issue
          To: amps at contesting.com, "Carl" <km1h at jeremy.mv.com>
          Date: Thursday, September 6, 2012, 1:21 PM


          Thanks guys, will let you know in a day or 2, I thought perhaps it may have the trap or simply jumpered...but I bought this from a ham, who seemed pretty knowledgable about amps, and was going to repair this himself but after 7 years, he never got around to it.. sounds familiar.. hi hi  .. So thats good, was anxious to surprise the local 10 meter group that I check into every Wed night.. 28.495 if anyone is interested...
           
          73, Tim K8WBL

          --- On Thu, 9/6/12, Carl <km1h at jeremy.mv.com> wrote:


          From: Carl <km1h at jeremy.mv.com>
          Subject: Re: [Amps] Dentron 160-10L 10 meter issue
          To: "Tim Kass" <k8wbl at yahoo.com>, amps at contesting.com
          Date: Thursday, September 6, 2012, 10:46 AM


          Id check to see if it even has 10M enabled and FL-1 removed or bypassed.

          Carl
          KM1H


          ----- Original Message ----- From: "Tim Kass" <k8wbl at yahoo.com>
          To: <amps at contesting.com>
          Sent: Thursday, September 06, 2012 8:57 AM
          Subject: [Amps] Dentron 160-10L 10 meter issue


          Hey Group,

          Well, finally got around to completing the project I bought a year ago...the amp had blown diodes. I replaced all the diodes, put in a circuit board for the new caps, upgraded the 811A's to new 572B's, put in a 6" inch fan, new circuit breaker and new, heavier, RF choke with suppressor kit (Ameritrons kit) ..works well except when I tried it on 10 meters last night...SWR infinite....was this one of those amps that Dentron put in the block for the 10 meter band so the Childrens Band folks dont try to use it? Seems like its a dead short...simple to open it back up again but also thought maybe it could be parasitics, etc...the manual states in capital letters to have the amp load and tune positions set to their specifications before attempting to transmit. I know Dentrons had issues with parasitics, reason for the new RF choke and top mounted suppressor kit... any thoughts? Carl? Just like to hear any suggestions or experiences before I open it
          back up again ... also..case is removed at it was shorting out to the top of the case on 20 meters, poor Dentron design to have any metal THAT close to the top of the main coil...probably what blew it up in the first place..guy told me he was operating it on 20 meters CW when it blew.

          73, Tim K8WBL
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