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
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
>Search: http://www.contesting.com/km9p/search.htm
>
>
___________________________________________________________________
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
|