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I recently acquired a Henry 2k-3 amplifier. It uses 2 3-500z's. I get =
good power out and it works very well, however, there are a few things =
happening that concern me.
1) When I got it home and plugged it in, I happened to touch the case =
and another radio that was grounded at the same time. Got a pretty good =
shock (not a lot of current). So I measured the voltage on the case of =
the amp to ground. 115 vac. The amp is wired for 220 vac. I checked over =
the schematic and the way it was wired the case was not grounded. I =
called Henry (got someone who could barely speak English) and they said =
that I should connect a jumper from the common wire on the 220 line =
coming in to the case of the amp. I did that and that fixed the problem. =
I still think that there could be something wrong.... why would there be =
voltage on the case in the first place? Leaky transformer?
2) I have a slight amount of 60 Hz hum in the RF out of the amp. Its not =
much but its there. I put a cw signal into the amp and sure enough the =
output waveform is modulated with ac looking at it on a scope. I =
thought that I might have a ground loop in the shack so I went outside =
and connected my tower ground (there are 5 ground rods driven around the =
base of my tower in a 24 ft radius) to the power company ground. I have =
known for a while that there was a little bit of current flow from my =
ground to the power company ground. Anyway, this did nothing for me, I =
still have the same problem.
I think that these two problems are related, but I have no idea how to =
cure it. I suspected that I might have a bad filter cap, I checked the =
high voltage and it reads 3200 volts... about what it should read. =
According to the front panel meter the voltage drops by about 300 volts =
with full power output. Not real good regulation as far as I'm concerned =
but the high voltage is still within spec. The book says it should be =
between 2800-3200 volts. The high voltage filter cap is a 20 uf oil =
filled cap. I have never seen one go bad......that doesn't mean they =
don't I just haven't witness it in the last 20 years of being an =
electronic technician.
I'm hoping that you amplifier experts can shed some light on the =
subject. Thanks for reading this.
Martin - N3HRT
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<DIV><FONT color=3D#000000 size=3D2>I recently acquired a Henry 2k-3 =
amplifier. It=20
uses 2 3-500z's. I get good power out and it works very well, however, =
there are=20
a few things happening that concern me.</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 size=3D2>1) When I got it home and plugged it =
in, I=20
happened to touch the case and another radio that was grounded at the =
same time.=20
Got a pretty good shock (not a lot of current). So I measured the =
voltage on the=20
case of the amp to ground. 115 vac. The amp is wired for 220 vac. I =
checked over=20
the schematic and the way it was wired the case was not grounded. I =
called Henry=20
(got someone who could barely speak English) and they said that I should =
connect=20
a jumper from the common wire on the 220 line coming in to the case of =
the amp.=20
I did that and that fixed the problem. I still think that there could be =
something wrong.... why would there be voltage on the case in the first =
place?=20
Leaky transformer?</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 size=3D2>2) I have a slight amount of 60 Hz =
hum in the RF=20
out of the amp. Its not much but its there. I put a cw signal into the =
amp and=20
sure enough the output waveform is modulated with ac looking at it =
on a=20
scope. I thought that I might have a ground loop in the shack so I went =
outside=20
and connected my tower ground (there are 5 ground rods driven around the =
base of=20
my tower in a 24 ft radius) to the power company ground. I have known =
for a=20
while that there was a little bit of current flow from my ground to the =
power=20
company ground. Anyway, this did nothing for me, I still have the same=20
problem.</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 size=3D2>I think that these two problems are =
related, but=20
I have no idea how to cure it. I suspected that I might have a bad =
filter cap, I=20
checked the high voltage and it reads 3200 volts... about what it should =
read.=20
According to the front panel meter the voltage drops by about 300 volts =
with=20
full power output. Not real good regulation as far as I'm concerned but =
the high=20
voltage is still within spec. The book says it should be between =
2800-3200=20
volts. The high voltage filter cap is a 20 uf oil filled cap. I have =
never seen=20
one go bad......that doesn't mean they don't I just haven't witness it =
in the=20
last 20 years of being an electronic technician.</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 size=3D2>I'm hoping that you amplifier =
experts can shed=20
some light on the subject. Thanks for reading this.</FONT></DIV>
<DIV><FONT color=3D#000000 size=3D2></FONT> </DIV>
<DIV><FONT color=3D#000000 size=3D2>Martin - =
N3HRT</FONT></DIV></BODY></HTML>
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