[HBR] 40m osc coil

[Brian Burns]

Hello Ian,

While wasting time this morning looking at back issues of Electric Radio, I
came across a soldering trick for heat sensitive (polystyrene/acrylic) coil
forms. A heat sink made from a water soaked pipe cleaner is wrapped around
the pin before applying heat---another trepidation reducer (;->)...

Cheers,

Brian

On Sun, Apr 19, 2015 at 10:01 AM, Ian Wilson <ianmwilson73 at gmail.com> wrote:

> Thanks to the great work of a list member I have a set
> of blank coil forms with 5-pin bases. Actually, I have four -
> a very good idea considering my ability to destroy things.
>
> The HBR-16 came with a 20m coil set only. However, this
> is a useful reference. The coils agree with the published
> info, so I know that the correct tuning cap was used.
>
> After some non-fatal mistakes (calculating the length of
> wire required and getting it wrong by a factor of 2, for
> example), I have a functional coil. However, the tuned
> winding is ugly and misspaced. This appears to be due
> to the Cu wire I used being too springy. It has lots of
> memory for kinks, etc. I plan to remove the winding and
> try rewinding it. However, I am not clear how a 6.5-turn
> winding occupying 3/4" can retain even spacing without
> some help - and it can't be anchored until the calibration
> is done. Hmm.
>
> The coil will tune to 8600kHz (monitored on a nearby
> receiver) with the tuning dial set for 7MHz. It's about 10%
> off at 7.2MHz. Not a bad start.
>
> I only have two 75pF APCs so won't be winding any 80m
> coils. 80m is not a very useful band for me at this QTH
> in any case.
>
> Since the radio has an existing tuning scale, I would like
> to fit the new coil to the old scale. I realize that this may
> be too difficult, though.
>
> 73, ian K3IMW
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