Need Help Troubleshooting PA of HW-5400

[Robert S. Capon]

Dear Heathkit Faithfuls:

I've been working on assembling an HW-5400 for the past six months, and am on
the last step of assembly and test.  The rig's receiver is working perfectly,
but I'm getting no power output at all.  I'm going to describe the problem,
and what I've done, and would appreciate any insight.  You can write to
"robcap at aol.com" or "w3dx at aol.com".  Either address will work.

The good news is that the receiver is working on all bands.  Good BFO levels.
 Strong signals.  Display and controller are working perfectly.

On XMIT, the side-tone works, and the amplifier relay kicks in.  However
power output is zero.  I mean flat zero.  No power measured on a QRP watt
meter that can read milliwatts.  Zero.

The troubleshooting guide says to check for .68 DC on biases on a number of
transistor bases.  I'm unclear whether the key should be up or down when
checking bias in the xmit strip.  On Q1201 and 1202 I get .68 on key down
only.  On Q1203 and 1204 as well as on the finals Q1206 and 1207 I get .68
volts on key down only.  My guess is that this is fine and that I'm getting
the correct bias along the PA strip.

The troubleshooting guide indicates to look for 13.8 volts on the collectors
of all transistors.  All are fine except for one of the matched finals.  The
collector reads -.3 volts.

I'm trying to determine if there is a wiring mistake, or if the final is
blown.  The final is in the vicinity of feed-through capacitors that hang
down from a metal shield.  Apparently, one of these shorted, because when I
was aligning the rig I got smoke from this vicinity.  I suspected the
feed-through capacitors had caused a short, and insulated them with
electrical tape.  After I insulated them, I reassembled the PA assembly, and
was able to do the pre-test and to set the bias voltage.

Unfortunately, I'm getting zero power output, and one of the matched finals
has the wrong voltage on the collector.

I'm looking for any insight into how one would test the transistor in the
circuit, and how you could determine whether it's a wiring mistake, or a
blown transistor.  Also, whether the bias measurements are key up or down.

Any help would be appreciated.

Everything that you've heard about the HW-5400 is true.  It is really slick.
It has great features, including a metal dimple on the tuning knob that zaps
off the last two digits of the display and tunes at a faster 1Khz tuning
rate.  The receiver works well.  Plenty of audio.  Keypad and xtal filter
also VFB.  The rig has split, RIT, etc.  But the rig is unbelievably
difficult to build.  There are 14 circuit boards, and two amazingly complex
wiring harnesses.  Chuck Penson indicates that the 100 hours it took to build
the rig is too much for most people, which is why the rig was pulled from the
market after only 1 year.  Chuck, I don't see how anyone could build this
radio in under 200 hours, and I've built approx 25 radios.

73,

Rob, W3DX

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