[ARC5] BC-454-B Dymamotor Question Part 2

[Mark K3MSB]

Hi Gang –



Well, I think it's been around a week and a half since I lasted posted on
my "saga",  but I did find some time on Saturday to rebuild my DM-32A for
my T-19.  I lubricated as per the manual and the work went OK.



Tonight I took some measurements.   There's still "hum" on the audio, but I
think it's a bit better.  Here’s some pictures of the new waveforms.  These
were taken by using a voltage divider (10K, 100K) into my scope,   and
taping off the socket upon which the dynamotor sits in the radio.



Picture 2858:

www.k3msb.com/temp/100_2858.jpg



40 mV P-P (scope at 20 mV / division)

Period of 9 mS (scope at 5 mS / division) which is 111.1 Hz.

Input voltage is 2.2 VDC from the divider, or 24.4  VDC into the radio.



Picture 2860:

www.k3msb.com/temp/100_2860.jpg



40 mV P-P  (scope at 20 mV / division)

Period of 9 mS (scope at 2 mS / division) which is 111.1 Hz.

Input voltage is 2.2 VDC from the divider, or 24.4  VDC into the radio.



Is this what’s it’s supposed to look like?



Raw input from my 28V supply (again, using my voltage divider)

Picture 2852:

www.k3msb.com/temp/100_2852.jpg



1 mV P-P  (scope at 1 mV/division)

Period about 17 mS (scope at 5 mS/division)  which is about 60 Hz.

Ripple is 1 mV from divider, or about 11 mV P-P (which is OK).





Now, here’s two pictures of the audio output (minimum gain), no voltage
divider used.



Picture 2864:

www.k3msb.com/temp/100_2864.jpg



30 mV P-P (scope at 10 mV/division)

Period about 5 mS (scope at 5 mS/division) which is about 200 Hz.



Picture 2867:

This 2nd picture is when I’m applying pressure to hold the dynamotor down!



www.k3msb.com/temp/100_2867.jpg

20 mV P-P  (scope at 10 mV/division)

Period about 5 mS (scope at 5 mS/division)  which is about 200 Hz.


Again, is this what I should be expecting from a dynamotor powered T-19 ?


73 Mark K3MSB