[HBR] Fw: Semi Experienced Builder

[Walt Hutchens]

> I understand the Eddystone dial was the best way to go. Anyone have
> any suggestions as to what the next best or third or fourth choice
> would be? I think I've settled on the HBR8.

I'll second the comment that the Eddystone takes a bit of work.
Basically the front end of the receiver has to be redesigned to
accommodate it.  While quite a few people have done so and the results
are on the HBR web site, it's a bit of a challenge: It's NOT so simple
as once you know how you just slap the dial on 'er and mark all the
holes ... that layout job was one of the more challenging ones I've
done.

The basic problem (in layout) is that the E. dial doesn't allow easy
measurement of where the cutouts and holes should go. Even if you get
the template, it's tough and most of the dials sold now are take-outs
from old projects, so no template.

It is pretty much a waste to get a pricey top quality dial and not get
it aligned perfectly with the tuning cap. Even a fairly small error
will lead to some backlash in the tuning.

Another excellent choice -- not much second best at all -- is the
6/36:1 Jackson Brothers drive used with almost any of the larger
National dials -- ACN, etc. Or you can use that drive with a home made
dial. The JB drive gives you the exact look of the original HBR but
with a dial that tunes slowly enough that you can tune in SSB signals.
AND the JB drive is a cinch to lay out and align.

As a first timer on a complex receiver I believe one is likely to do
better (have more fun AND a receiver that works well!) with the JB
drive.

> Would one of the HBRs with single use tubes be easier and less
> cluttered for a "semi experienced" person like me?

Opinions are going to vary on this, but the receivers with
multi-section tubes definitely trade socket hole count for congestion
around those holes.  When you have less 'elbow room' it's more
important that wiring be right the first time.

The 'up side' of the greater congestion is that good multi-section
design can be executed on a slightly smaller chassis than the
equivalent done with single-section tubes.  But that's not
particularly something to want, early in one's constructor career.

With single section tubes you sometimes get a spare pin on the socket
that can be used as a tie point. (Check that the tube specs say 'NC'
before doing this, though, as sometimes something IS connected -- it's
just not something you would use.) And you have more space per section
for mounting tie points -- always a challenge for the new constructor,
unless your directions tell you exactly what and where.

It's good practice to lay out your parts so that any of them can have
the value read, both ends available for measurements when
troubleshooting, and if necessary be replaced without removing other
parts. That's a bit tricker with multi-section tubes.

Multi-section tubes do save you some filament wiring and occasionally
a bit more than that when electrodes of the two sections are directly
connected, as in a common-cathode mixer or direct-coupled audio amp.
When designing they can sometimes allow reducing lead lengths by
useful amounts.

Did you ever wonder why subminiature tubes never went anywhere? Cost
was a major factor, but they also offered a lot less advantage than
you'd at first think. Except for dual triodes, there are no
muli-section subminiatures, so you really save very little space by
using them. And the wiring job is a bear and the result more trouble
prone and harder to troubleshoot because of the small clearances.

All these are 'soft' issues.  The receiver that seems most interesting
to you is the one you should build.

Walt Hutchens
KJ4KV