On Sun, 17 Jan 1999 10:35:57 -0800 "Mike Michon" <michon@eatel.net>
writes:
>
>Checked the tubes for filament to grid short. One tube was shorted
>from
>filament to grid.
>
>Hooked tube from filament to grid to a 12 volt car battery and burned
>shorted parts off.
Now that is an interesting method! I have a few duds here that I will try
that on.
The tubes put out 1200 watts again. For how long we
>will
>see.
Try one tube at a time on or 20M with 50W drive to see how balanced they
are.
>
>Thanks for the information.
Check condx of parasitic resistors. If they are OK you probably had a
nice internal tube arc. Get a HV glitch resistor installed ASAP and a
1N5408 on the ckt board. Parts are stocked at Mouser.
73 Carl KM1H
>Mike Michon
>AB5XP
>
>
>Technical information about tube repair method from Richard WA5NYG
>
>
>
>
>
>
>----------
>> From: Mark S Graalman <wb8jkr@juno.com>
>> To: michon@eatel.net
>> Cc: km1h@juno.com; amps@contesting.com
>> Subject: Re: [AMPS] AL-82
To: <amps@contesting.com>
>> Date: Sunday, January 17, 1999 3:45 AM
>>
>> Sounds like a filament to grid short to me.
>>
>> Mark WB8JKR
>>
>>
>> On Sat, 16 Jan 1999 22:44:19 -0800 "Mike Michon" <michon@eatel.net>
>> writes:
>> >
>> >Replaced the diode on circuit board, it was on schematic, and was
>bad.
>> >Replaced with a IN4141 because that was all I had. No difference in
>
>> >the
>> >wild red glowing of plates.
>> >
>> >Checked zener diodes in center tap of filament transformer. Red
>lead
>> >of
>> >meter to threaded post of zener diode #1 .559 mega ohms. Reversing
>
>> >leads
>> >1.35 mega ohms.
>> >
>> >Zener #2 red lead of VOM to threaded post 1.4 mega ohms.
>Reverersing
>> >leads, 14.1 mega ohms.
>> >
>> >Running amp with zeners disconnected, still big red glow and 300 ma
>on
>> >plate current meter.
>> >
>> >Also, the grid current meter is reading backwards, ie, pegging in
>the
>> >left
>> >hand direction, or below zero.
>> >
>> >Our brains are mush and we are going to bed.
>> >
>> >Thanks for your reply.
>> >
>> >Mike Michon
>> >AB5XP
>> >
>> >----------
>> >> From: km1h@juno.com
>> >> To: amps@contesting.com
>> >> Subject: Re: [AMPS] AL-82
To: <amps@contesting.com>
>> >> Date: Saturday, January 16, 1999 5:05 PM
>> >>
>> >>
>> >>
>> >>
>> >> On Sat, 16 Jan 1999 18:26:18 -0800 "Mike Michon"
><michon@eatel.net>
>> >> writes:
>> >> >
>> >> >I have an AL-82 amp that was doing OK till yesterday. I turned
>it
>> >off
>> >> >and
>> >> >on quickly yesterday morning. It was 4 am and I was half asleep,
>so
>> >I
>> >> >don't
>> >> >know why I did it.
>> >> >
>> >> >A line fuse blew. I replaced it. Now the amp plates start
>glowing
>> >> >red, as
>> >> >if drive is applied, with antenna out of tune or not properly
>tuned
>> >
>> >> >up.
>> >> >
>> >> >A visual inspection reveals nothing obviously cooked or fried.
>> >> >
>> >> >A 1 hp motor connected in series with the 220 volt input to HV
>> >> >transformer
>> >> >drops the HV to 800 volts so we can observe it a while longer.
>The
>> >
>> >> >motor
>> >> >stays in Locked rotor indicating a heavy load from the plates
>being
>> >
>> >> >in
>> >> >conductivity.
>> >> >
>> >> >Any ideas as to what is going on?
>> >>
>> >>
>> >> For starters:
>> >>
>> >> Replace the diode on the PS board that is not designated on the
>> >> schematic. It is a 1N4001 between the B- rail and real ground.
>> >Replace
>> >> with a 1N54x series.
>> >>
>> >> That is a very common AL82 failure mode that also destroys tubes,
>
>> >blows
>> >> suppressors, etc. At the very least I would install a 20 Ohm 20W
>WW
>> >> resistor in series with the HV lead.
>> >>
>> >> Ameritron/MFJ will not admit to any problems so dont waste ur
>time.
>> >Sorta
>> >> like dealing with Henry !
>> >>
>> >> I'm off for the eve/night but let me know ur results...will be
>back
>> >tmw.
>> >>
>> >> 73 Carl KM1H
>> >>
>> >>
>> >>
>> >> >
>> >> >Mike Michon
>> >> >AB5XP
>> >> >
>> >> >
>> >> >--
>> >> >FAQ on WWW: http://www.contesting.com/ampfaq.html
>> >> >Submissions: amps@contesting.com
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>> >> >
>> >> >
>> >>
>> >>
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>> >
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>>
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>
___________________________________________________________________
You don't need to buy Internet access to use free Internet e-mail.
Get completely free e-mail from Juno at http://www.juno.com/getjuno.html
or call Juno at (800) 654-JUNO [654-5866]
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
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