[Heathkit] Heathkit SB Essay.

[kiyoinc at attglobal.net]

I wrote this the other day, here is a fresh edit:

On Heathkit SB's.

The problem with Heathkit's SB transceivers isn't the soldering.
That's an old-ham's saw.  It's not quite up there with the "Acid Core"
urban legend, but it's close.

While I have encountered poor solder jobs, I have only seen one
problem that was clearly solder based and that was in a factory,
machine-made part.

The problem with Heath are the mechanicals.  The design is clever;
the parts are mediocre; the mechanical build quality is generally
horrible.

A case in point is the LMO pinch drive and the tension on the rings.
I've spent hours cleaning, polishing, and adjusting the drive and when 
it's right, it's terrific.  It's light, smooth, precise, no backlash. 
I have a Heath SB tuning knob with lead weights in it.  It's a perfect 
match for the LMO drive.

I had an SB pinchdrive shaft that was dragging. 35 years of corrosion 
will do that to metal. I hand polished the shaft with 1200 grit, oiled 
it, got it turning right in the brass sleeve.

I carefully cleaned the LMO dial ring and tensioned the drive disks. 
Then it takes several times of trial and error to get the disks on the 
right part of the ring.

Even when you have the pinch drive adjusted right, the 100 kHz
indicator is off.  That's a 30 minute trial and error adjustment where
1/64 inch position shift of a piece of metal under a machine screw is
amplified by an articulated arm.    After the fine tuning, you're
fighting the play in stamped parts.

Then there's the fiduciary on the LMO.  What's with that?

Every fiduciary knob is corroded.  I polished one until it shines.
It's still just a knob on a 1/8 inch shaft in a hole drilled in plastic, 
no fore-aft stop, driving a piece of wobbly plastic with friction.  The 
plastic hairline may have chips on the edge.  Nothing you can do about that.

Another problem with Heath are the thin skirts on the knobs.  The
skirts could be thicker and more precise.  When I put the knobs back
on a Heath, I use a feeler gauge to space the skirt from the front
panel. 1/8th inch is about right. That's after I find the low spot on 
the skirt.

This is after I clean the dirt out of the knob flutes with a wood 
toothpick and polish the plastic with a silk cloth.

The bezel on the SB's should be more like Collins.  That was a bad
place for Heath to cut corners. A thick solid bezel would give the
fiduciary's drive shaft more bearing surface.

How did Heath get the bezels on the DX-60 and the HW-16 so right and
the SB so wrong?

The phenolic circuit boards are mediocre.  The design is fine.  Thick
FR4 glass epoxy would have made the Heath's much better.

On sheer performance, the Heath's are up there. The 6HS6 (or FETs in the 
SB-303)) give .25 microvolt sensitivity. Hot receivers, 6 pole
crystal filters, rock-stable, 1 kHz readout, etc. Transceiver slaved to 
a full Receiver. Drake and Halli couldn't do that well until they went 
digital.

de ah6gi/4