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@bigpond.com>
To: <amps@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@bigpond.com>
> To: <amps@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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