[Amps] More Capacitors vs LC filters

Alek Petkovic vk6apk at bigpond.com
Thu Apr 19 17:32:30 PDT 2012


"Aha! The old money in the bank from the mug punters trick." (Maxwell Smart)

Guess I better get that heater voltage measured and set sooner rather 
than later.

Hey, by the way, what is the plate voltage on the AL-1500 supposed to be 
if it ain't 3600V?

Thanks and cheers, Alek.
VK6APK

On 20/04/2012 8:20 AM, Carl wrote:
> As with many pulse tubes thats likely the same filament as an 8877 
> being run hot in order to get the peak emission needed. Life will be 
> shorter and more money will be made.
>
> Carl
> KM1H
>
>
>
>
> ----- Original Message ----- From: "Alek Petkovic" <vk6apk at bigpond.com>
> To: <amps at contesting.com>
> Sent: Thursday, April 19, 2012 7:36 PM
> Subject: Re: [Amps] More Capacitors vs LC filters
>
>
> I think I'm the 3rd or 4th owner of the amp and I'm slowly "going
> through it". I have some 500V/105°C capacitors on order to replace the
> 450V ones. I think the existing ones are 220uF and the new ones will be
> 330uF. Close enough.
>
> As I am aware that Ameritron amps are notorious for higher than spec
> filament voltages, I have put a 3CPX1500 tube in the amp for the time
> being. It believe it has the 5.5V heater and I figure I'll be safer with
> that until I get around to measuring and adjusting the voltage at the
> pins. I was going to address it when I swap out the filter caps. (So
> many damn screws holding the lid down and the chassis straight!)
>
> According to the wiring and labelling, the transformer is running on the
> 240V primary.
>
> AC line voltage here is pretty good. I just measured it at 239V. We are
> supposed to have 240V. I've seen it drop to around 236V and rise to
> around 243V. It is 7:30am on a cool autumn morning here in this small
> seaside town. Heaters won't be in use but toasters and kettles will be.
>
> 73 and thanks,
> Alek. VK6APK
>
>
>
> On 20/04/2012 6:29 AM, Carl wrote:
>> What is the AC line and filament voltage at no load Alek.
>>
>> Ive also been told that a "number" of the 3 senior aps received
>> incorrectly wound transformers that were not caught during test.
>>
>> Supposedly distributors have serial # info as well as the factory.
>>
>> Otherwise Id buck the input down 15V or so while making sure the
>> filament is in spec using the internal connections or an external
>> transformer.
>>
>> Carl
>> KM1H
>>
>>
>> ----- Original Message ----- From: "Alek Petkovic" <vk6apk at bigpond.com>
>> To: <amps at contesting.com>
>> Sent: Thursday, April 19, 2012 6:22 PM
>> Subject: Re: [Amps] More Capacitors vs LC filters
>>
>>
>>> Very interesting Jim.
>>>
>>> I get very nervous having my Ameritron AL-1500 sitting here less than 2
>>> ft away from me, especially at start up time.
>>>
>>> It has 8 x 450V elecrolytics in series and the plate voltage meter 
>>> reads
>>> exactly 3600V. They are running at 100%!
>>>
>>> 73, livin' on the edge, Alek. VK6APK
>>>
>>>
>>> On 20/04/2012 3:51 AM, Jim Thomson wrote:
>>>
>>> (snip)
>>>>      I only operate these caps  at 70-75%  of the max V rating.
>>> (snip)
>>>>
>>>>
>>>> later... Jim  VE7RF
>>>>
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>>>
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>>
>
>


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