I don't figure why, but (here we also have 50 Hz line frequency)
with many transformers we have hum, adding a thick (1.5 mm) carton
between transformer and chassis completely solve the problem; in extreme
cases, adding rubber grommets between mounting and chassis fix the rest.
That of Aluminum is new for me. Maybe sone sort of mechanical resonance?.
Best regards
Guillermo - LU8EYW.
RICK COLE escribi?::
>Can some-one give me a short explanation WHY a piece of METAL should improve
>the hum...I have 50hz mains power here in Australia and never seen this here
>in any of the amps i have looked at...I have tried to reason why the metal
>REDUCES the hum but so far cannot come up with a feasable answer...to me
>anyway!!
>regards Rick
>
>----- Original Message -----
>From: "Skram, Helge (MED)" <helge.skram@med.ge.com>
>To: "Osten B Magnusson" <sm5dqc@algonet.se>; <amps@contesting.com>
>Sent: Thursday, June 26, 2003 12:49 AM
>Subject: RE: [Amps] AL-80A question
>
>
>
>
>>Hi
>>
>>Here is the answer received from Ameritron about the transformer hum using
>>an AL-80B on 50 Hz
>>I have not tried it yet, since I use an hard object of placed between the
>>chassis and operating desk.
>>
>>Reply from Ameritron, Mike Enis:
>>
>>When an Amplifier is ship out of the USA, there is a plate that is placed
>>between the transformer and chassis. Use an aluminum plate the size of
>>
>>
>the
>
>
>>bottom of the transformer. It only has to be about 1/16 inch thick. This
>>will reduce the affect of the transformer to chassis when on 50 Hz.
>>
>>73 de LA6MV
>>Helge Skram
>>
>>
>>-----Original Message-----
>>From: Osten B Magnusson [mailto:sm5dqc@algonet.se]
>>Sent: 25. juni 2003 11:00
>>To: amps@contesting.com
>>Subject: [Amps] AL-80A question
>>
>>
>>
>>
>>Friends!
>>
>>As you maybe know, answers from Ameritron to questions
>>are kept very short... The AL-80A transformer is very noisy
>>when used here in Europe on 50 Hz. Ameritron says:
>>
>> >> An aluminum plate can be secured under the transformer to elimate the
>> noise.
>>
>>Is this true, and if so, how large and thick should it be?
>>
>>Thanks in advance and 73 de Osten SM5DQC sm5dqc@algonet.se
>>
>>
>>
>>
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>>
>>
>>
>
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