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Re: [Amps] AL-1500 'thump'

To: David Gow <6146guy@gmail.com>
Subject: Re: [Amps] AL-1500 'thump'
From: Aleksandar Petkovic via Amps <amps@contesting.com>
Reply-to: vk6apk@bigpond.com
Date: Thu, 19 Feb 2026 06:32:59 +0800
List-post: <mailto:amps@contesting.com>
Yes. That's correct. I have bought quite a few items through his website and Tom has also provided valuable technical help at times.

73, Alek VK6APK.

On 18/02/2026 10:30 am, David Gow wrote:
He is the original designer of the Amertron amps.

On Tue, Feb 17, 2026 at 2:38 PM Aleksandar Petkovic via Amps <amps@contesting.com> wrote:

    Thanks mate.

    73, Alek VK6APK.

    On 18/02/2026 1:00 am, maflukey@gmail.com wrote:
    > His ebay store is "W8JI CTR Engineering All Things Ham"
    >
    
https://www.ebay.com/str/w8jictrengineeringallthingsham?_trksid=p4429486.m3561.l161211
    >
    > Matt
    > KM5VI
    >
    >
    > -----Original Message-----
    > From: Amps <amps-bounces@contesting.com> On Behalf Of Aleksandar
    Petkovic via Amps
    > Sent: Monday, February 16, 2026 10:42 PM
    > To: amps@contesting.com
    > Subject: Re: [Amps] AL-1500 'thump'
    >
    > I wasn't aware of his ebay store. Can you provide a link please?
    >
    > Yes, I have his filter board and the EBM Papst blower in my
    AL-1500, but I bought them directly from him. I would like to see
    the ebay store.
    >
    > 73, Alek VK6APK
    >
    > On 17/02/2026 12:07 pm, maflukey@gmail.com wrote:
    >> FYI, W8JI sells upgraded HD capacitor boards, upgraded HD
    rectifier boards, and upgraded soft start boards for the big box
    Ameritrons on his ebay site.   IMO they are very well designed,
    assembled, tested high quality boards that I seem to recall Tom
    describing as the boards that would have gone into the AL-1500 had
    production costs not needed to be considered.   The boards have
    several improvements from the originals and are relatively easy to
    install.
    >>
    >>
    >>
    >> Matt
    >>
    >> KM5VI
    >>
    >>
    >>
    >> From: Rejean Leveille <rejva2am@gmail.com>
    >> Sent: Monday, February 16, 2026 2:42 PM
    >> To: maflukey@gmail.com
    >> Cc: Steve Bookout, NR4M <steve@nr4m.com>; amps@contesting.com
    >> Subject: Re: [Amps] AL-1500 'thump'
    >>
    >>
    >>
    >> Hi
    >>
    >> In the past my soft start relay got defective, also with age it
    may not read the right high voltage, easy fix be replacing the
    Mohm resistance..
    >>
    >> Also if the HV was near 3600 volts, there is no safety
    electrolytic margin at 450 volts. All equalizer resistors need to
    be very close values. If their color doesn't look like new then
    replace them all by ordering twice (16x). to pick up the 8x match.
    >>
    >> Unless you have some safety experience measuring each
    electrolyte DC
    >> voltage then do not do it. The diode pcb needs to be vertically
    locked
    >> and insulated
    >>
    >> Good luck
    >>
    >> Rejean  va2am
    >>
    >>
    >>
    >> On Mon, Feb 16, 2026 at 12:52 PM <maflukey@gmail.com
    <mailto:maflukey@gmail.com> > wrote:
    >>
    >> For safety's sake, be aware the soft start and safety interlock
    on some of the AL-1500s were not factory wired per the schematic.
    >>
    >> Matt
    >> KM5VI
    >>
    >> -----Original Message-----
    >> From: Steve Bookout, NR4M <steve@nr4m.com <mailto:steve@nr4m.com> >
    >> Sent: Monday, February 16, 2026 8:48 AM
    >> To: maflukey@gmail.com <mailto:maflukey@gmail.com>
    >> Cc: amps@contesting.com <mailto:amps@contesting.com>
    >> Subject: Re: [Amps] AL-1500 'thump'
    >>
    >> Hello Matt,
    >>
    >> I was wrong about the soft start.  It IS in the AL-1500.
    >> My mistake was I asked ‘AI’.
    >> On the schematic, it’s obviously there (K3 and a 10 ohm R).
    >>
    >> Steve NR4M
    >> Sent from my iPhone
    >>
    >>> On Feb 15, 2026, at 8:45 PM, maflukey@gmail.com
    <mailto:maflukey@gmail.com> wrote:
    >>>
    >>> Hi Steve,
    >>>
    >>>>> 'If' it had a soft start to deal with initial current surge, I
    >>>>> might think there was a problem there, but there isn't one.<<
    >>> Did you remove the soft start relay and inrush resistor?     
    How old are your PS caps and are they original or upgraded?
    >>>
    >>> Matt,
    >>> KM5VI
    >>>
    >>>
    >>>
    >>> -----Original Message-----
    >>> From: Amps <amps-bounces@contesting.com
    >>> <mailto:amps-bounces@contesting.com> > On Behalf Of Steve Bookout
    >>> Sent: Sunday, February 15, 2026 12:39 PM
    >>> To: amps@contesting.com <mailto:amps@contesting.com>
    >>> Subject: [Amps] AL-1500 'thump'
    >>>
    >>> Hello all,
    >>>
    >>> Had a friend using the station this weekend, and while sitting
    there with him, while operating on 40 meters, we both heard a
    'thump' or 'thungg' from the amp while transmitting.  Happened two
    or three times or a period of a few hours.
    >>>
    >>> Reminded me of the sound the current surge makes when you
    first turn the HV on in an amp.
    >>>
    >>> Puzzling to me cuz if that was it, why and why now?   And, no
    other follow up issues.  I don't think a PS filter cap would
    'sorta, kinda'
    >>> short, then not and be OK.   It would only be a small part of
    a larger 'event'.  (Been there; done that and still remember the
    pucker factor.)
    >>>
    >>> Amp was being operated in a typical fashion, with resonant
    load, 25 watts of drive, ~ 40 ma grid current,  +/- 1200 watts RTTY.
    >>>
    >>> Dealt with many amps before, but have not heard anything like
    this in the past.  'If' it had a soft start to deal with initial
    current surge, I might think there was a problem there, but there
    isn't one.
    >>>
    >>> Ideas?
    >>>
    >>> 73 Steve NR4M
    >>>
    >>>
    >>>
    >>> _______________________________________________
    >>> Amps mailing list
    >>> Amps@contesting.com <mailto:Amps@contesting.com>
    >>> http://lists.contesting.com/mailman/listinfo/amps
    >>>
    >>
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    >>
    >>
    >>
    >>
    >>
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