HW-16 HUM

[Dennis Klipa, N8ERF]

My HW-16 has a hum that is quite noticeable when the volume is set low and
less so when it is turned up.  I have read all of the previous emails on
this issue in the Archives for the HW-16 so you don't have to waste your
time teaching me that again.

I have two questions about the hum in my HW-16, since there are two
distinct hums.  Hmmm.

1. There is a noticeable hum when the speaker is disconnected from the
transceiver.  I believe it is coming from the transformer.  Not a good
sign for the transformer.  The question is; can these mechanical
vibrations cause an electronic hum to be generated in the audio circuit
due to vibrations of the elements within the tubes?

2. I have recapped the HW-16 except for the 4-part can.  I skipped that
one because it had been replaced before I got the transceiver and I
couldn't find one to buy, so I thought I would try to get by without
replacing it.  I did like the one suggestion of stuffing individual caps
inside the original can after removing the original contents, though.

I have measured the AC voltages for the 5 DC supply voltages and would
like to get the opinion of the "experienced" as to whether these numbers
are acceptable or whether I should go ahead and recap the can again.  Here
are the numbers.

Supply   DC Volts    AC
A         175        33 mV
B         310        0.84 V
C         320        30 mV
D         700        1.4 V
E        -150        90 mV

I believe that A,C and E are OK, but I am not so sure about B & D.

Thanks for the help.

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