Saturday, June 21, 2008

Take care of your radio

So many cheap consumer electronics
that go bad sitting around out there.
Here are my top recommendations
for making your radio last:

---Remove batteries when you set aside.
Batteries still ooze caustics sometimes
when they get old.

---Wrap the radio in a plastic bag!
Dust makes that volume control
crunchiness, and can wipe out
the carbon film of the volume control

---Keep it cool and dry if you can.
Capacitors inside have a lifetime.
Hot attics can kill. Room temp is good.
A cool basement, if the humidity is
not high, will make things age slower.

---don't buy speakers with foam
surrounds around the cones. Foam
rot wrecks speakers. Some are
still made with weak coated porous foam.

Thursday, June 12, 2008

more on untuned loops

Untuned loops like to be large single turn things.

I taped two 4 ft long fiberglass driveway marker rods
for a 7 foot span last night and draped wire off the ends.

A 2 turn, 3inch diameter coil was wound onto one side,
to couple to the pocket radio.

The reception boost was fantastic.
3-4 turns on a 24inch square were not even close.

It's awkward to find supports and clearance, but ~18 ft
of wire straight across a 7 ft top boom, hanging down
(with the mentioned coupler to radio) is a fantastic
BCDX loop antenna. It would make a great thing to
take camping away from houses and wiring, since
it packs up into a hand-reel (of 22ga) of wire, some
tape, and two fiberglass rods. You could kite-string it
from a tree and tune the continent for $5-10, plus
a pocket radio like the $10 Sony.

Sunday, June 1, 2008

The Untuned Loop

Here is a gadget I have seen scarcely covered
elsewhere: the

AM DXers are all familiar with the tuned loops
you can use to boost range. But we are all familiar
also with the constant tweaking and tuning of the loop.

A few years ago, I make an untuned loop and had a good
time tuning it day and night times, up in the mountains
of Maine. So this time, I brought my plain Sony ICF-S10MK2
pocket AM/FM radio, and parts for the loop. you make one: you make a big rough single loop
of wire (clipped to itself at the end) on a dining table, hanging
to the floor. You wrap a coupling loop (3-4in. diameter)
around a hand and twist-tie it together. Then you slip
it beret-style over the top side of the radio, and tune away.

Results were a fair boost at night, and a big gain in qty.
of stations in daytime. Going bigger gives major improvement
though. In order to do that, you need a loop "top frame" bigger
than a dining table. Two 4-ft dowels lashed helps. Going from
5 feet to 8 feet, and 13 feet total wire to 20 feet, really brings
the signal in. An excellent untuned loop would be an X-shape
with maybe 4-foot spokes stuck in a drilled block, and wire
taped or eye-hooked out at the ends.

The untuned loop is a little combersome, but I love not
having to fiddle and tune it.