No, Ryan, I haven't had the time to fiddle with it. The buzz comes and
goes on my supply. It was very loud the other day, but mostly it is not
too bad. The buzz is almost always silent when I turn on the amplifier.
It slowly builds up in amplitude as the amp warms up, although sometimes
if I leave the amp on long enough (on order 30 minutes) the buzz die
back down and go away completely. I suspect it is, as a number of
commentators suggested, some sort of armature effect (a loose piece of
steel moving in response to the time varying magnetic field of the
transformer winding) that has a temperature dependence. Other than this
buzz, the amp appears to work fine.
73, Mike W4EF..........
On 3/25/2010 8:05 AM, Ryan Foster wrote:
> Mike,
>
> Did you ever find a solution to this?
>
> I have also just developed the same problem and can find no electrical
> reason for it, and I honestly don't understand any mechanical reason for it
> to search for that.
>
> --Ryan w8cya
>
> On Mon, Feb 15, 2010 at 2:49 PM, Michael Tope<W4EF@dellroy.com> wrote:
>
>
>> On 2/15/2010 10:05 AM, Carl wrote:
>>
>>> Could be a bad cap, one installed wrong (it will blow eventually but
>>> it will get real warm first), missing, miswired or bad equalizing
>>> resistor.
>>> The transformer is trying to tell you to stop!
>>>
>>> Carl
>>> KM1H
>>>
>>>
>> Carl/Dick, et al.
>>
>> I triple checked the polarity of the caps before I put the cover on the
>> PS and they are installed properly. Also, I didn't see any swelling or
>> smell anything from the PWB after I fired up the supply, but I'll pull
>> the lid off and take a closer look.
>>
>> Regarding Dick K5AND's suggestion, the transformer is held is 8 places.
>> 4 bolts on the bottom, and 4 on the top. I had the bolts on the top out
>> to replace the 50Kohm x 50W power resistors used to derive the cutoff
>> bias. That may have changed the mechanical pre-load on the transformer.
>> Maybe I'll let the PS warm up and then loosen and re-tighten those bolts
>> to see if that helps.
>>
>> Thanks,
>>
>> Mike W4EF...........
>>
>>
>>
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