[HBR] 40m osc coil

[WA5VGO]

Soldering polystyrene forms isn't difficult. Remove the plating first. Use some fine emery cloth to polish the bottom of the pin. Then carefully run a drill bit that's slightly larger than the hole through it. The soldering surface should be bright, shiny brass. Now use a soldering iron that has enough power to solder the pin quickly. Too small of an iron is worse than too large. Get the heat on and get if off. The forms don't melt as easy as you might think. 

Darrell


> On Apr 19, 2015, at 1:40 PM, Brian Burns <brianburns1066 at gmail.com> wrote:
> 
> 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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