-=jd=- wrote:

On 01 Jul 2003, craigm wrote:

Joe Strain wrote:

...snip...
Can we have some practical experience here from the
"listeners" about whether the resistors should be 10K or
200 K ?

Yodar


10k is a good value for the resistor.

In this application the resistor is in parallel with the
bulb. Its purpose is to bleed off any static that
generates. In this case, lower is better, but you want to
keep the value well above ( 10X ) the impedance of whatever
is connected.

When there is a nearby strike, more voltage will be
generated on the antenna. When the voltage exceeds 90
volts, the lamp fires. It discharges the antenna until the
voltages drops below 65 volts. After that, the resistor
bleeds off the rest.

When using the lamp as a pilot light, the resistor is in
series with the bulb. This is done to limit current. Too
much current and the bulb's life is shortened.

As another poster mentioned, a balun tends to put
everything at ground potential anyway.

None of this is sufficient to handle a direct strike. Also
a sufficiently large nearby strike could still cause damage
to a radio.

Enjoy

Craig

I was hoping someone would verify that the resistor is parallel
with the bulb - I had second thoughts after reading Joe's post.
As for lightning protection, I'm thinking that if a lightning
strike hits that close or directly, I'm probably screwed
regardless. I'll opt for disconnecting the ant. when not in use.

I have now strung the whole affair up. As previously stated,
except that from the 14' post at the house to only about 8' up
the the tree for now (I'll need a sling-shot to hit the 30'
mark). Even so, the difference is remarkable!

The drop-off in ambient noise is remarkable. I tried the three
different antennas (dx mode) while tuned to 10mhz and found
that:

Coax-Fed Random Wire - clear as a bell and signal meter was
maxed on 5 and stayed there (scale 1 - 5). I'm presuming the
coax feed along with the 30' rope extending the antenna way from
the house were the significant factors as I disconnected the
static-filter/balun unit and could not tell a bit of difference
(with my uncalibrated ear-ball). Seemed to be similar results on
other freqs.

Built-In Aerial - The stations was in and out, I could pick up a
beep occasionally over the noise. Signal meter fluctuated from 1
to 3, but I think that was more the noise level.

Wind-up Ant: Worse than the Aerial. Nothing but noise. Signal
meter fluctuated from 2 to 4.

Either that particular freq did not present the circumstances
where the static-filter/balun would be worthwhile -or- the
static-filter/balun really doesn't do much for me regarding
reception improvement. In any event, it doesn't seem to have an
effect either way, so no harm done that I can tell. That, and
winding it salvaged an otherwise rainy afternoon...

So I'm wondering if a balun is a waste of time on a random wire
for SWL only. At least, in the case of Joe Listener just
sticking a length of wire up - not in the case of big beverages
or some other "formal" (lack of a better word) antenna rig...

Are you sure you have the balun/matching transformer wired and connected
properly?



JD
--
"Who are you going to believe, me or your lyin' eyes?" -Groucho
Marx