[Elecraft] [KPA500] incredible hum from PA

[kevino z]

Thanks Ron. I'll open it up and measure it with a torque wrench. Then wait for Elecraft tech support to call back. Sometimes it's a drag living on the East Coast :-(
-Kevin (KK4YEL) 

No trees were killed in the sending of this message. However, a large number of electrons were terribly inconvenienced !

> On Dec 19, 2016, at 22:53, Ron D'Eau Claire <ron at cobi.biz> wrote:
> 
> Joe might be right but contact Tech Support first. The transformer is held in place with a single large bolt through the center (it is a torodial transformer). If that bolt is not tightened properly the magnetic field will produce a huge vibration. Even if you did not build the amp from the kit, it's a pretty simple job to tighten that bolt. Tech Support can lead you through the process. It is also described in the kit assembly manual available on the Elecraft web site here;
> http://www.elecraft.com/manual/E740149%20KPA500%20Kit%20Assembly%20Manual%20Rev%20F6.pdf
> 
> See pages 36 and 37. 
> 
> 73, Ron AC7AC
> 
> -----Original Message-----
> From: Elecraft [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of W1GO (Joe)
> Sent: Monday, December 19, 2016 6:19 PM
> To: kevino z
> Cc: Elecraft Reflector
> Subject: Re: [Elecraft] [KPA500] incredible hum from PA
> 
> Kevin,
> 
> Yes.  had the problem.  Crazy loud hum / buzz.  Bad transformer I was told.  All quiet on the eastern front now.  If it is a bad transformer it can be fixed but you’ll have to eat the shipping charge.
> 
> Joe
> W1GO
> 
>> On Dec 19, 2016, at 9:10 PM, kevino z <z_kevino at hotmail.com> wrote:
>> 
>> Just got my KPA500 and KAT500. I hooked the PA up to 240v (well, my Mains are 248v), so I made sure the assembled PA has the yellow transformer tap, from the factory.
>> When I engage the amp, there is a crazy buzz. I use a KPA500 at work, but it is on 120v and I never hear this buzz. Before I swap fuses, and switch over to 120v to test, does anyone else have this issue?
>> The KPA500 is hooked up to a KX3/KXPA100 combo, just in case someone would ask.
>> Thanks
>> -Kevin (KK4YEL)
>> 
>> 
>> No trees were killed in the sending of this message. However, a large number of electrons were terribly inconvenienced !
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