[Amps] Ameritron AL-1200

[jeremy-ca]

Gerald, see an eye doctor!

>From his original post:

>> So I replaced the Resistors, This  Time with 75K OHM Flame proof 
>> Resistors,
>> all Eight of them with the  same wattage and replaced all Eight
>> Electrolotyic Capacitors, all I  had were 220MFD at 450VDC

However if the replacement caps were those little imports its no wonder they 
failed.

Carl
KM1H




----- Original Message ----- 
From: <TexasRF at aol.com>
To: <n9bx at mchsi.com>; <Amps at contesting.com>
Sent: Tuesday, October 30, 2007 3:45 PM
Subject: Re: [Amps] Ameritron AL-1200


>
> Sounds like eight new capacitors and eight new bleeder resistors would 
> take
> care of the immediate problem. After multiple failures there is a 
> likelihood
> that the remaining capacitors have been stressed enough that their days 
> are
> numbered.
>
> 73,
> Gerald K5GW
>
>
> In a message dated 10/30/2007 1:00:43 P.M. Central Daylight Time,
> km1h at jeremy.mv.com writes:
>
> There  are those who would have you believe that Ameritron used a special
> capacitor not available to us common folk. I have no idea if it is true 
> but
> I suggest that you call Ameritron and dont rest until you are put in 
> touch
> with someone who is in the position to  answer.
>
> Carl
> KM1H
>
>
>
> ----- Original Message -----
> From: <n9bx at mchsi.com>
> To: <Amps at contesting.com>
> Sent:  Tuesday, October 30, 2007 1:03 PM
> Subject: [Amps] Ameritron  AL-1200
>
>
>> Hi:  I have a perculiar problem with the high  voltage power supply on 
>> the
>> AL-1200.  Here is the sequence of  events.
>>
>> I had the Amplifier on and it was idling and all of a  sudden it 
>> crackled,
>> stopped and about 15 minutes later did this  again.  High Voltage stayed
>> the same ,(meter Indicates 3600-3700  VDC,  The whole time.  Well I shut 
>> it
>> down and after the HV  was alowed to bleed off I started checking the
>> filter  cpacitors.  this amp used 210 MFD at 450 VDC and Had eight of 
>> them.
>
>> Yes I know that 8X450 =3600 Volts, and that's about what my voltage 
>> reads
>> on the meter but I figured the designers of this Amp knew what  they were
>> doing and there was an adequate safety margin built  in.
>>
>> Well One of the Capacitors was Bad.  In fact the  little white Dot that 
>> is
>> on the Capacitor was bubled up and the  Capacitor did not charge or
>> discharge.  I then checked all of  the 50K ohms 7 watt resistors across 
>> the
>> Caps and sure enough two of  them read open.  These were the ones that 
>> were
>> across this Cap  and the one Adjesent to it.
>>
>> So I replaced the Resistors, This  Time with 75K OHM Flame proof 
>> Resistors,
>> all Eight of them with the  same wattage and replaced all Eight
>> Electrolotyic Capacitors, all I  had were 220MFD at 450VDC so Hey A 
>> little
>> bit more voltage regulation  key down but not that much.
>>
>> Turned the unit back on   Everything was fine.  Made one QSO, Voltage was
>> above 3600 VDC  again as before and I thought the Amp was back in 
>> Business.
>> Well  after sitting with no load on it two hours it started crackling
>>  Again, and one again it does this at about the 15 minute  interval.
>>
>> I am almost sure that I will find the same Bad  components agin, but What
>> is causing the Capacitors, Or more likely  the equalizing resistors to 
>> fail
>> which causes the Caps to  Fail.
>>
>> Sorry for the Bandwidth but this amp has been in service  for 12 Years 
>> with
>> not a hint of Problems before This Started to  Happen.
>>
>> 73 Bruce N9BX
>>  _______________________________________________
>> Amps mailing  list
>> Amps at contesting.com
>>  http://lists.contesting.com/mailman/listinfo/amps
>>
>
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