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Re: [Amps] AL-1500 'thump'

To: <vk6apk@bigpond.com>, <amps@contesting.com>
Subject: Re: [Amps] AL-1500 'thump'
From: <maflukey@gmail.com>
Date: Tue, 17 Feb 2026 11:00:34 -0600
List-post: <mailto:amps@contesting.com>
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
>>
>>
>>
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>
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