[HBR] HBR Website

[Walt Hutchens]

> I wonder also if you could let me know how I can get a set of the drilling
> templates for the HBR-16/  Are folks still   building? My inquiries for parts
> have been pretty discouraging, (no surprise there!) so have been ordering out
> materials for HB coils, cans., etc.

I think that one reason drilling templates are hard to find is that there
are so many variations on these receivers that -- while seemingly minor --
turn out to more or less affect the layout.

To take the biggest example the receivers were designed around the MCN/ACN
(etc.) series of dials.   But as SSB progressively took charge of the ham
world, a better dial (more reduction) became almost essential and people
went in various directions.   Many used the Eddystone 898 but the price of
doing so was a major redesign of the chassis.   A few used command receiver
tuning caps; that was yet another totally different design.   Some did
various home made or adapted gear reduction schemes; some of these worked
with (roughly) the original layout and some did not.  Others went with
string drives ...

I've now built three HBRs.   None of them has the original type dial and not
a one is even close to the original layout.   One each: Command set, 898,
string drive ... they all work, but the layouts had to be different.

Then you add in the different types of IF cans used -- especially now, when
IFTs for this sort of design aren't off anyone's shelf, the choices of tube
types that weren't common in the late 50's-early 60's, much smaller
electrolytic caps ...

Even S-meters are often different now -- many of us would use smaller meters
than in the original W6TC design, meaning less clearance is required.

I think the best way forward is to find your parts first.   It is probably
best to avoid using parts nobody else has used for that job.   Then pick a
set of pictures on the HBR site -- every possible HBR design is there! --
and lay your parts out in a similar manner.   Take your ruler, mechanical
pencil, and a sheet of paper and start sketching, measuring and writing the
measurements on your sketch.   You will of course adjust many measurements
as you go: Spacing two parts by 63/64" makes no sense: you'll use 1"   As
you make these adjustments, relocate the parts on the chassis accordingly.

You'll also see opportunities to move a group of parts in line with one
another.    Doing so will look better and make layout both easier and less
error-prone.  

Follow the exact same steps with the front panel -- put parts on the panel,
measure, make dimensioned sketch.   Do it again for the rear apron of the
chassis.

When you have a sketch with dimensions, tape a piece of wrapping paper
tightly to the top of the chassis.  (Paper grocery bags work well.)   Take
your dimensioned sketch and lay that out on the papered chassis.   Do the
front panel the same way and prop the panel against the chassis.

Put all the parts in their marked locations and RETHINK EVERYTHING.   In
particular look for conflicts between stuff on top of the chassis and what's
under it, and between items in the front (and rear) panel and parts mounted
on the chassis that might project into the same space.   (Common example:
S-meter sticks back too far to allow putting the nearest tube in its socket.
Another:  Tuning capacitor shaft goes through one of your tubes or right
under the socket making wiring a real challenge.   Yet another: Fuseholder
on the rear panel collides with the bottom of your power transformer or a
choke you put under the chassis.)

Also think about replacing parts.   Okay, you have a used volume control.
It measures okay with an ohmmeter but what if it's seriously noisy?   Can
you get it out without removing the tuning cap which would require removing
the dial ... ?   

An advantage of (roughly) copying an existing design is that you shouldn't
have many such issues, but it never hurts to check.

The antenna and mixer coils must have a shield between them and it must be
bigger than you think.   The more space you can allow around the oscillator
coil the more stable the receiver will be.   KEEP HEAT SOURCES AS FAR AWAY
FROM THE OSC. COIL AS YOU CAN.   OR put a shield plate in between ...
Assuming you're copying a working design, the meaning of these cautions is
don't squeeze or adjust dimensions to give you a smaller shield or put the
antenna and mixer coils closer together than in the original.

Put a solid block under the chassis and centerpunch all the holes.   Start
drilling, smallest holes first.   (If you drill one too many, nothing is
hurt because you were going to drill that one larger anyhow.)   It's not a
bad idea to mark all the holes of one size in a distinctive manner -- say
with a dot of red magic marker.   Then drill those and mark the next batch.
Put your parts on the chassis a few times as you go, just to confirm ...

Don't try to do too much at one shot: Fatigue causes mistakes and a socket
hole punched where you were going to mount a shield plate is ... annoying.

Anyone can do this stuff.   If this is a first multi-tube project it will
pay handsomely to go slowly but you can get just as nice a result as someone
who has done several.

Walt
KJ4KV