[Henry] Henry 2KD Classic help?

[Rocco Lardiere]

Kelly,

See if the arc occurs on all bands, or just some; if it's only one band, you
have a big clue to the suspect hardware.  Try slowing ramping up the drive
level and see if the arc occurs only at high power; that may tend to suggest
something in the plate circuit.  I have found similar problems by turning
out the lights and looking carefully at the RF section from several angles,
even through the screens.  Sometimes you can hear the arc, too.  You can
remove the cabinet and screens if you know how without shorting out the HV
and take a close but extremely carefuly look; watch out for the shorting
assembly.  You may need to look at the underside, also.  Usually an arc due
to corrosion or loose mechanical connections can be seen - and you can then
pinpoint the problem.  Check for loose or unsoldered wires at the tube base
filament connections.  These can easily overheat with extended use and
simply melt the solder, causing intermittent connections.  This happened to
my amplifer, although the tube actually went dark (easy to find that
problem!)  One warning - 3-500's do not like to operate on their sides,
sometimes; the elements can move around and short out - very common.

Another thing to try is to simply clean all the switch contacts with DeOxit
and tighten down all the critical HV hardware.  Some things are tougher to
get at.  Things like parasitic suppressors (both ends) tend to work loose
and can cause what you are seeing.  I found some loose hardware in my 2KD5.
Be sure to visit the relays with DeOxit and a clean white card - mine had
corrosion buildup after 10 years of intemittent use.

Another simple thing to try is to pull one tube , then the other - try it
one tube at a time.  That can help isolate the problem to either a tube or
specific components associated with it.  If you have a spare 3-500Z,
substituting that can pin it down to a suspect tube.  Yes, you can run one
tube at a time, but be careful about the drive level and other arcs - you
end up with dangling HV RF components with one tube out.   I know someone
who ran an SB220 for years with one tube, but he removed some of the drive
components under the chassis.

With any of this, safety first.  This things can kill you, but you knew
that!  You have a great amplifier - I would not part with mine.

Hope this helps.

73,

Rocco N6KN
----- Original Message -----
From: "Kelly Jones" <kjones@sullivan1.com>
To: <henry@mailman.qth.net>
Sent: Saturday, February 15, 2003 3:18 PM
Subject: [Henry] Henry 2KD Classic help?


> Hello List...
>
> I was working the ARRL Contest this morning and left the rig and amp on to
> do daily errands.  When I came back about 8 hours later I was very
> disillusioned when I keyed the radio and my amp began making a
> buzzing/arching noise.  The arc seems to vary with intensity from none at
> all to pretty loud.
>
> The amp is a 2KD Classic desktop.  Plate is running about 400ma and grid
is
> about 330ma.  Normally it runs ~600 plate and 225ish grid.
>
> Both tubes are lit normally and I don't see anything unusual when the amp
> is keyed.  It's difficult to tell where the arc is coming from.  And to
> make matters worse, it doesn't seem to arc every key.  The SWR is running
> about 1.5-6.1.  I *think* the SWR was lower than that originally.
>
> Is it possible one of the tubes may have gone bad?  They are Eimacs, but I
> don't recall if they are the originals.  I have owned the amp for about
> three years and have never had a lick of problem with it.  I can't recall
> if the guy I bought it from said they were originals or not.
>
> Can this amp be run with one tube at a time?  That might shed some light
if
> so.  When it rains it pours.  Two days ago my TS850 decided it wanted to
> whig out too.... shees, not much more here that can break!
>
> Thanks for any suggestions.
>
> Kelly - KE9KD
>
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