[Yaesu] Problem in FT-101E -100v Circuit (Jerry Pittman)
GGLL
nagato at arnet.com.ar
Mon Feb 16 19:40:47 EST 2004
Hello Jerry, I suggest not to replace that cap. with a similar one
because sooner or later you'll have the same problem. They're prone to
have losses (= lower Resistance) with time. You can try a pair of disk
ceramic capacitors (NP0) or a silver mica one, of not less than 500 V
working voltage (nearly 350V on standby at 12BY7 plate plus some
-60..-80V on final grids, that makes a total V of 430V across this
capacitor).
Glad to help you
Best regards
Guillermo - LU8EYW.
Jerry Pittman wrote:
>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
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>Send Yaesu mailing list submissions to
>>>>>>>yaesu at contesting.com
>>>>>>>
>>>>>>>To subscribe or unsubscribe via the World Wide Web, visit
>>>>>>>http://lists.contesting.com/mailman/listinfo/yaesu
>>>>>>>or, via email, send a message with subject or body 'help' to
>>>>>>>yaesu-request at contesting.com
>>>>>>>
>>>>>>>You can reach the person managing the list at
>>>>>>>yaesu-owner at contesting.com
>>>>>>>
>>>>>>>When replying, please edit your Subject line so it is more specific
>>>>>>>than "Re: Contents of Yaesu digest..."
>>>>>>>
>>>>>>>
>>>>>>>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------------------------------
>>>>>>>
>>>>>>>_______________________________________________
>>>>>>>Yaesu mailing list
>>>>>>>Yaesu at contesting.com
>>>>>>>http://lists.contesting.com/mailman/listinfo/yaesu
>>>>>>>
>>>>>>>
>>>>>>>End of Yaesu Digest, Vol 14, Issue 9
>>>>>>>************************************
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>_______________________________________________
>>>>Yaesu mailing list
>>>>Yaesu at contesting.com
>>>>http://lists.contesting.com/mailman/listinfo/yaesu
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>_______________________________________________
>>>Yaesu mailing list
>>>Yaesu at contesting.com
>>>http://lists.contesting.com/mailman/listinfo/yaesu
>>>
>>>
>>>
>>>
>
>
>
>
>
More information about the Yaesu
mailing list