wrote in news:7c6ef9ff-4081-4fd7-bbab-
:

I generally prefer the loops vs a random wire. In the daytime with
ground wave, no contest. With the loop you can almost totally null
daytime ground wave signals. At night, much less directional with the
sky wave, but the station will still often sound better using the loop.
I did a test in 2002 between a 16 inch round loop, and a 42ft "T" vertical
with a 120 ft long flat top wire. That would be fairly similar to using
a long random wire as far as overall performance.


Those files are very convincing. As well as the orientation there seems to
be a vast improvement based on capturing energy at a small region in space, a
long wire seems to mush out the signal maybe partly due to occupying so much
space. Maybe I misundrstand, but it does seem like the spatial resolution of
a loop's small occupancy has a direct relation to the resolution of the
demodulated signal.

Anyway, thanks, I'm sold on the idea. I spent a couple of hours last night in
cool damp windy conditions gathering some NDB notes on a 50m longwire
stretched WNW then NNW (to an amazingly well placed tree, the distances
varied by less than one foot!) I lost my notes later that night in little
incident with an Organiser RAMpack and a low main battery, but I can remember
delberately testing the transmissions last thing before I packed up, and
while the longwire did seem to have a directional difference, the mushiness
did not help at all. Also, we have a high pressure region breakign down,
there seemed to be storms in southern Europe, France/Spain most likely. I
imagine a magnetic loop might dramatically reduce the impact of that noise
too.

I think someone posted some design notes or links during one of my first
threads a month or so ago. I'll look at your loop in detail (I like the
narrow but stuff gauge of UPVC pipe (I'll maybe chose a black 20mm conduit
because that's easy and cheap to get here, and I've used it for other stuff
too), and hopefully I'll figure out a good waterproof capacitor for loop
tuning too.

One question: Is this going to be good using the 100 or so turns I put on the
end of the PL-390 ferrite rod? Hopefully this is the ideal way to couple the
signal into the radio, because it will make life very easy if it is.

Lostgallifreyan wrote in
:

stuff

'stiff'..

On Saturday, September 13, 2014 1:00:11 PM UTC-5, Lostgallifreyan wrote:


Those files are very convincing. As well as the orientation there seems to

be a vast improvement based on capturing energy at a small region in space, a

long wire seems to mush out the signal maybe partly due to occupying so much

space. Maybe I misundrstand, but it does seem like the spatial resolution of

a loop's small occupancy has a direct relation to the resolution of the

demodulated signal.

The 50m wire is not going to be too directive on such low frequencies.
It's not acting as a long wire or beverage. It's way too short.
It's just a random wire and will be fairly non directional on LW and MW.
So you pretty much hear everything on freq, and it can sound like mush
if multiple stations are being heard.




I think someone posted some design notes or links during one of my first

threads a month or so ago. I'll look at your loop in detail (I like the

narrow but stuff gauge of UPVC pipe (I'll maybe chose a black 20mm conduit

because that's easy and cheap to get here, and I've used it for other stuff

too), and hopefully I'll figure out a good waterproof capacitor for loop

tuning too.

Being as the caps used are generally old broadcast variables and such,
you could just have a plastic cover over it. But I use all mine indoors
where I can turn them, and don't worry about that. I'm not going to sit
out in the rain to listen to a radio. :/

The type PVC doesn't matter much as long as it's rigid enough to keep
from bending with the wire tension.
I've built them from the usual white PVC which I think is 3/4 inch OD,
and I've got a big one that uses a thick 2-3 inch?? or so piece as a mast,
and 3/4 inch PVC run though drilled holes on the thick PVC mast. So pretty
much only two pieces not counting the T's. The 16 inch loop you heard
on the recording is about 12 or so turns wound on a plastic blower housing
with a mount on the back.

It's a round loop, and sits on the floor in one of my stands. It can
tune the whole MW band. The big loop I have which is a 44x44 inch diamond,
uses a cap out of an old stereo. It has multiple gangs which I can switch
in and out. I think it tunes from around 500 to 2000 kc or so.. And lower
if I tack on extra fixed caps.




One question: Is this going to be good using the 100 or so turns I put on the

end of the PL-390 ferrite rod? Hopefully this is the ideal way to couple the

signal into the radio, because it will make life very easy if it is.

I have no idea what you mean by the PL-390 ferrite rod.. Sounds like a
small antenna on it's own with 100 turns of wire.. ??

I feed the small loops with either a single turn coupling loop to coax,
or if you use a portable you can just use the ferrite bar antenna in the
radio, and close couple it to the loop by holding them close together and
finding the sweet spot where you get max signal.
Of course if you did that, you would want to rig a mount to hold the radio
in place.

I fed all mine with coax, usually to my IC-706mk2g. I remember one time
I tried the 16 inch loop on a AC Delco car radio that was in my truck.
It was hot as a firecracker using that loop for an antenna. Much better
than the truck whip.

Some will speculate that the balance could suffer from using coax directly
to a single turn coupling loop with no balun, etc.. But it's never been
a problem for me. You can tell by the deep nulls I get, that balance
is not an issue. I can make daytime ground wave signals totally vanish
if I null them out, and the nulls are inline with the loop and not
skewed. So no problemo using that feed method here.. :|

wrote in news:a44e119a-e3c4-4380-b611-
:

Being as the caps used are generally old broadcast variables and such,
you could just have a plastic cover over it. But I use all mine indoors
where I can turn them, and don't worry about that. I'm not going to sit
out in the rain to listen to a radio. :/


I've been caught up in other doings for a while (old Psion machines, buying,
programming, etc..) so I re-marked as unread because I need to read more
carefully, but just a couple of things for this post..

I won't sit in the rain either. I used to repair stuff for people, and
found that dust and airborne volatiles have a habit of settling on air-spaced
cap vanes, and some old tuning caps get very furry with surface corrosion
too, making them harder to clean safely. Even a dry night can have a heavy
dew... And a few encounters with boxes with IP ratings says those that keep
water out are the ones that are usually best at keeping all the other crap
out too.

The other thing, a question.. Is it important to space the coils out on the
UPVC frame? I imagine that changes inductance, and may be used as a way to
adjust tuning in addition to using a variable capacitor, but is there some
other reason, i.e. is there some specific compromise that aims to get the
lenth of wire into a small spatial region without compacting the coils so
close togeher as to raise inductance a lot? (I ask because I'm considering
possible implications on aiming for a compact portable device. If I can lay
the coil very flat, I'd like to do so.)

Hello again. Not forgotten... Still doing other stuff but I try to return to
this especially as colder nights mean less chances I'll want to spend hours
in the dark on open land messing with long wires...

While looking at your JPG with the loop design I did an entirely gratuitous
bit of graphic editing because I find bright backgrounds hard to handle when
lookign at things for a long time. Do you want a copy? If so, let me knwo
where I can send it..

I notice you mentioned a 'pancake' or 'solenoid' choice of coil that partly
answers the question I asked on the 16th, but I'm not sure what the
difference makes, and there is also the possibility of winding a flat spiral.
What difference do these variations make on reception? Also, is there a
specific advantage of the spaced turns (solenoid, as used in your design)
rather than making a simple circle of windings, that overcomes the
inconvenience of what is a fairly fragile and awkward shape to carry on foot
for long distances? I'm looking for some advice on this because even though I
can build this as it is, I want to try to organise the order I do things in.
I'm still workign on my beverage reel thing, had to wait for a drill that I
just paid for and started using only last night.. It also means I should be
able to build other things now.