[ARC5] BC-454-B Dymamotor Question

[Mark K3MSB]

Thanks Gents;  I have not taken apart either dynamotor, but will do so this
weekend.

All caps in the receiver are replaced.

When I'm not powering the dynamotor,  I'm using the same 28V supply to
provide 28V directly to the radio along with 250V from an HP-23A.

Here's the waveforms by the way:

http://www.k3msb.com/temp/dynamotor_1.jpg
170 Hz waveform.

http://www.k3msb.com/temp/dynamotor_2.jpg
1250 Hz waveform (hard to tell)

73 Mark K3MSb

On Thu, Jan 17, 2013 at 8:01 PM, David Stinson <arc5 at ix.netcom.com> wrote:

>
> ----- Original Message ----- From: "Mark K3MSB" <mark.k3msb at gmail.com>
>
>
>  Is what I'm hearing with the dynamotors normal?
>>
>
> Not at all.
> Here are common causes of dyno noise:
>
> *  RF bypass caps in the ends of the dynamotors    directly across the
> brushes bad.
> *  Bad 5 mFd B+ buss filter.
> *  Bad .22 uFd bypasses (the big bathtub cap).
> *  Bad brushes.
> *  Worn or dirty communtator.  Consult    Mike Hanz's work before
> attempting    to clean or burnish commutators.
> *  Bad or dry dynamotor bearings.
>
> Check these and we'll go from there.
>
> 73 DE Dave AB5S
>
>
>