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@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@yahoo.com> wrote:
From: Tim Kass <k8wbl@yahoo.com>
Subject: Re: [Amps] Dentron 160-10L 10 meter issue
To: amps@contesting.com, "Carl" <km1h@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@jeremy.mv.com> wrote:
From: Carl <km1h@jeremy.mv.com>
Subject: Re: [Amps] Dentron 160-10L 10 meter issue
To: "Tim Kass" <k8wbl@yahoo.com>, amps@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@yahoo.com>
To: <amps@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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