The much lower Q of the molded inductor can result in significantly
worse rejection of spurious outputs from the amplifier. I don't know
whether that's important for this particular design or not. But a toroid
also has other advantages over a solenoidal inductor. A toroid has a
much smaller external field, so it can be mounted close to other
components including other inductors with minimal mutual coupling. For
the same reason, a solenoid's Q can be degraded substantially by
proximity to other components or conductors, while a toroid is
relatively immune to this problem.

Roy Lewallen, W7EL

Ben Jackson wrote:
In a coupling circuit such as:

C1|| C3||
IN----||----o----o----||--OUT
|| | | ||
--- C
--- C L1
C2| C
| |
'----'
|
===
GND

(see, eg, the "38 Special" NorCal 30m QRP tranceiver sch connecting
the NE602 single-ended output to an amplification stage:
http://www.amqrp.org/kits/38spcl/ )

What is the purpose maximizing the Q of L1 by using, say, a hand-
wound toroid vs a molded inductor? Rs of a 1.8uH moulded inductor
might be 1.5 ohms vs .1 ohm for 5 inches of 24ga wire. However the
expected effect in tank bandwidth doesn't seem to matter compared to
the large effect of varying C1 (very narrow for small C1, 5p in the
example).

I can see why a homebrewer would prefer to keep a bag of T37-2 and
some enamelled wire around, but in a kit such as that, wouldn't a
moulded inductor do just as well?