[Yaesu] Problem in FT-101E -100v Circuit (Jerry Pittman)

Mon Feb 16 13:48:43 EST 2004

Hello Guillermo,
Yes, you are right about the finals.  I had discovered that one of the
6js6c's had gone shorted on several pins after testing them on my Sencore
tube tester.  The driver also showed greatly reduced life test, so I have a
complete set of valves on the way.  I'm thankful I got the tip on the C13
cap before the new tubes arrived.  I was starting to think their failure
cause the voltage problem and not the other way around.

That cap is an 80pf 1KWV so if they don't have it, I'll try matching up a
couple of 40pf 500v like you suggested.  Thanks for the suggestion, since
they probably won't have the original mica cap available.

73 Jerry

----- Original Message ----- 
From: "GGLL" <nagato at arnet.com.ar>
To: "Yaesu" <yaesu at contesting.com>
Sent: Sunday, February 15, 2004 9:20 PM
Subject: Re: [Yaesu] Problem in FT-101E -100v Circuit (Jerry Pittman)

>     I've forgotten to add, that you must realign the driver and final
> grid section for the upper bands (best if you perform a complete RF
> re-alignment as per manual), where you may note the worst tracking
> difference after C13 capacitor change.
>
> Good luck
> Guillermo - LU8EYW.
>
> GGLL wrote:
>
> >    Are your final tubes fine after C13 short?; that failure will turn
> > very positive final tube's grid bias, which causes an indeed high
> > plate current. Check them before you go to the shop. If I don't miss,
> > C13 was a 100 pF rectangular old style mica cap. You could replace
> > them with two 47 pF, 500V NP0 disc ceramics in parallel as I did in
> > several 101's with good results.
> >
> > Best regards
> > Guillermo - LU8EYW.
> >
> > Jerry Pittman wrote:
> >
> >> Correction!!!  Sorry Rick,  I spoke to soon.  I pulled the C13 cap
> >> from the
> >> circuit and found that it had shorted.  You were dead on for the
> >> diagnosis.
> >> Now to go to the electronics shop tomorrow.
> >>
> >> Thanks a Million!!
> >> 73 Jerry
> >> WD4OIX
> >>
> >> ----- Original Message ----- From: "Jerry Pittman"
> >> <jerryp49 at worldnet.att.net>
> >> To: "R_Davis" <WD8JJA at arrl.net>; <yaesu at contesting.com>
> >> Sent: Sunday, February 15, 2004 5:59 PM
> >> Subject: Re: [Yaesu] Problem in FT-101E -100v Circuit (Jerry Pittman)
> >>
> >>
> >>
> >>
> >>> Thanks for the tip Rick.  I checked that cap and it appears okay, so
> >>> the
> >>> search goes on.
> >>> Jerry
> >>>
> >>>
> >>> ----- Original Message ----- From: "R_Davis" <WD8JJA at arrl.net>
> >>> To: <yaesu at contesting.com>
> >>> Sent: Saturday, February 14, 2004 12:41 PM
> >>> Subject: [Yaesu] Problem in FT-101E -100v Circuit (Jerry Pittman)
> >>>
> >>>
> >>>
> >>>
> >>>> Check the coupling capacitor, C13, between the 12BY7A and the finals.
> >>>> Rick, WD8JJA.
> >>>>
> >>>> ----- Original Message -----
> >>>> From: <yaesu-request at contesting.com>
> >>>> To: <yaesu at contesting.com>
> >>>> Sent: Saturday, February 14, 2004 12:00 PM
> >>>> Subject: Yaesu Digest, Vol 14, Issue 9
> >>>>
> >>>>
> >>>>
> >>>>
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> >>>>> Today's Topics:
> >>>>>
> >>>>>   1. Problem in FT-101E -100v Circuit (Jerry Pittman)
> >>>>>
> >>>>>
>
>>>>> ---------------------------------------------------------------------- 
> >>>>>
> >>>>>
> >>>>> Date: Fri, 13 Feb 2004 12:41:26 -0500
> >>>>> From: "Jerry Pittman" <jerryp49 at worldnet.att.net>
> >>>>> To: <yaesu at contesting.com>
> >>>>> Subject: [Yaesu] Problem in FT-101E -100v Circuit
> >>>>> Message-ID: <006e01c3f258$9b485ac0$6101a8c0 at JerryPittman>
> >>>>> Content-Type: text/plain;
> >>>>> charset="iso-8859-1"
> >>>>> MIME-Version: 1.0
> >>>>> Content-Transfer-Encoding: quoted-printable
> >>>>> Precedence: list
> >>>>> Reply-To: Jerry Pittman <jerryp49 at worldnet.att.net>
> >>>>> Message: 1
> >>>>>
> >>>>> Hello to all,
> >>>>> HELP!  I wonder if anyone has run into this problem:
> >>>>>
> >>>>> My 101E was just idling along while I was working on the computer
the
> >>>>>
> >>>>
> >> =
> >>
> >>
> >>>>> other evening, when I started smelling something hot.  I shot the
rig
> >>>>>
> >>>>
> >> =
> >>
> >>
> >>>>> off immediately and found that the bias control (VR1) on the
> >>>>> voltage =
> >>>>> control board (PB1547B) had over heated, as well as the (2) 10K =
> >>>>> resistors on either side of the control.
> >>>>>
> >>>>> When I check the voltage at pin 5 of the 1547 board, I found that it
> >>>>>
> >>>>
> >> was
> >>
> >>
> >>> =
> >>>
> >>>
> >>>>> getting -160v instead of -100v.  I went to the Rectifier board
> >>>>>
> >>>>
> >> (PB1076B)
> >>
> >>
> >>> =
> >>>
> >>>
> >>>>> and made tests there.  When I disconnected the lead from the -100v =
> >>>>> terminal, the voltage shows -60v but with it is connected it shows =
> >>>>> -160v.  With the lead disconnected I also tested it for AC voltage
> >>>>> and
> >>>>>
> >>>>
> >> =
> >>
> >>
> >>>>> it shows 125vac as well as -60vdc.
> >>>>>
> >>>>> I checked all the components on the 1076B board and found all okay,
> >>>>>
> >>>>
> >> but
> >>
> >>
> >>> =
> >>>
> >>>
> >>>>> just to be sure I hadn't missed something, I put in a used PB1076B
> >>>>>
> >>>>
> >> board
> >>
> >>
> >>> =
> >>>
> >>>
> >>>>> and found all of the same readings.  I had already checked all of
the
> >>>>>
> >>>>
> >> =
> >>
> >>
> >>>>> other voltages coming and going from the 1076B and all are correct =
> >>>>> except the -100v.  The voltages from all of the transformer taps
> >>>>>
> >>>>
> >> appear
> >>
> >>
> >>> =
> >>>
> >>>
> >>>>> to be within range as well.
> >>>>>
> >>>>> Does anyone have an Idea or run into this before?
> >>>>>
> >>>>> Thanks in advance for any responses.
> >>>>> Jerry
> >>>>> WD4OIX
> >>>>> jerryp49 at att.net------------------------------
> >>>>>
> >>>>> _______________________________________________
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> >>>>> Yaesu at contesting.com
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> >>>>>
> >>>>>
> >>>>> End of Yaesu Digest, Vol 14, Issue 9
> >>>>> ************************************
> >>>>>
> >>>>>
> >>>>
> >>
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> >>
> >>
> >>
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