开云体育

At 04:01 PM 8/7/04 +0000, you wrote:

I just bought a Sangean PRD-2 radio.? It works great on the internal
AM antenna.? Just for experimentation, I want to hook up an external
loop antenna.? It has 2 terminals on the back.? One marked "am
antenna" and the one next to it marked "ground".? My question is,
where do the 2 wire leads from the antenna go?? I assume the ground
is for a ground wire and not the antenna.? Do the 2 wire leads from
the antenna both go to the terminal marked "am antenna"?? What??????????????????????????????????

?
The radio more than likely uses a ferrite rod antenna/front end inductor.? If it has a terminal for the AM receiver it will in all likely hood be connected to a wire link wound around the ferrite rod.? In this case you have 2 choices for coupling to a tuned loop.

1.? Simply ignore the connectors and making a physical connection between the loop and the radio.? Tune the radio to the frequency of your choice, then tune the loop to the same frequency and orient the loop and radio for best reception.

2.? If your loop has a pair of wires coming out (usually from a coupling link) then simply connect one wire to the 'AM Antenna' connector and the other to the one marked 'ground'.? If the wire from the loop is a coax type wire, then connect the centre conductor to the 'AM Antenna' connector and the shield to the 'Ground' connector.

Experiment with both methods.

???????????????

Jim Dunstan
Thunder Bay, ON

RR,

AM/MW Loop Antennas: Your best 'connection' may be NO Connection.

Use the AM/MW Loop Antenna "Inductively Coupled" to the
Radio's built-in AM/MW Ferrite Rod Antenna.

IMHO: Most of the time Inductive Coupling works better
than a direct connection to many radios that have built-in
AM/MW Ferrite Rod Antennas.

READ: About Inductive Coupling with a Loop Antenna and
a 'portable' AM/MW Radio


READ: Improved AM/BCB Radio Reception = Think MW Loop Antenna


READ: Passive and Active AM/MW Loop Antennas


iane ~ RHF
.
.
= = = In loopantennas@...,
= = = "realrussian" <realrussian@y...> wrote:

I just bought a Sangean PRD-2 radio. It works great on the

internal

AM antenna. Just for experimentation, I want to hook up an

external

loop antenna. It has 2 terminals on the back. One marked "am
antenna" and the one next to it marked "ground". My question is,
where do the 2 wire leads from the antenna go? I assume the

ground

is for a ground wire and not the antenna. Do the 2 wire leads

from

the antenna both go to the terminal marked "am antenna"?
What ?

.

开云体育

The only dumb questions are those that don't get asked.

Two ways to go:

(1) Antenna screw to a really long wire strung outside. Ground
screw to a cold water pipe in your house.

(2) Antenna screw to the signal end of a loop antenna like we
describe on this group, ground screw to the ground connection. Be
aware that loop antennas are tuned devices, they will have to be
adjusted to the same frequency to which the radio is tuned to be
effective.

开云体育

From experience I would connect inner to AM Antenna and outer to ground.
Whether the internal loopstick will cause problems I do not know. Orientation of receiver will help here.
Is the external loop amplified?
Other method is to wind 2 or 3 turns onto internal ferrite aerial and connect external loop or wire antenna to one end and ground wire to the other
As with all unknowns-try it and see. If it works then tell others about it
If not then research on WEB
regards
dave G8SZX.

loopantennas@... wrote:

hi all , am parting out a technics st-s1 tuner to build a tunable
loop. every thing but the variable cap is available. all switches
knobs andface panel are good the tuner was working yesterday. any
takers?
question regarding the variable cap. there are 3 screws on the
top and a trimmer.where should the wires of the loop be connected?
thanks in advance johnkelsall

I just bought a Sangean PRD-2 radio. It works great on the internal
AM antenna. Just for experimentation, I want to hook up an external
loop antenna. It has 2 terminals on the back. One marked "am
antenna" and the one next to it marked "ground". My question is,
where do the 2 wire leads from the antenna go? I assume the ground
is for a ground wire and not the antenna. Do the 2 wire leads from
the antenna both go to the terminal marked "am antenna"? What?

Greeting folks.
I am currently attempting to build a Loran-C (centered at 100kHz)
receiver and am having some difficulty with the antenna. Though I
have been frequently informed it is difficult to not pick up this
signal, I seem to be quite accomplished at it. My only attempts to
pick up the signal consist of hooking the leads of various AM
antennas to the 50 ohm input of a spectrum analyzer via a matching
network for 100kHz. Any recommendations as to how I should
build/purchase an antenna for this frequency and how I should test
it? Also, does anyone happen to know what the polarization of the
Loran-C signal is?
Thanks,
Matt

I have built a couple of loops on styrofoam - they work great.

At 11:33 AM 7/27/04 -0600, you wrote:

Hi,

I got given some poly square plastic stuff and thought hmm I could use this
in a loop somehow and this popped into my mind I am thinking 15 inches on
the outside with wood and the lengths on the inside holding it together that
poly square plastic stuff is 1/2 inch square. So that would make the loop
14.5in square not huge but decent I figure. I was thinking of bringing the
coupling loop in about an inch or two from that so the coupling loop would
be 13.5in or so to 12.5in not sure which is better. was going to make the
"plate" to hold the cap out of lexan and the "plate" for the connections
back to the receiver. question is how many turns of wire for the AM BCB I am
sure there is a calc for this but I haven't seen it and I wanted to share my
design. Also the rest wood be made from wood the longer pieces.


Scott
KC7WDG

My second post. I took a look at your construction schematic. U are using 4 pegs sandwiched between 2 frames. My construction is similar but different. If you look at your schematic cross section (from the side) ... I have just one frame and the pegs are mounted with 1 screw each to only one frame. The other end of the peg is free. The frame I use is simply a plywood sheet (a plexiglass sheet and pegs would be classy). I mount my capacitor in the center on the opposite side of the sheet from the winding. I screw one end of a 12" peg on the same side of the sheet as the winding. I then slide my coupling coil (8" dia. 3 turns) along this peg for optimum coupling.

I mount the whole thing vertically on a 8" square block which acts as a base. I glued a sheet of velvet material on the bottom to avoid scratching the HiFi set.

For normal listening on the HiFi I just slide the pickup hoop right in the loop .... nothing critical. When I am dxing with another receiver I find the coupling adjustment is invaluable.


Jim Dunstan
Thunder Bay, ON

At 11:33 AM 7/27/04 -0600, you wrote:

Hi,

I got given some poly square plastic stuff and thought hmm I could use this
in a loop somehow and this popped into my mind I am thinking 15 inches on
the outside with wood and the lengths on the inside holding it together that
poly square plastic stuff is 1/2 inch square. So that would make the loop
14.5in square not huge but decent I figure. I was thinking of bringing the
coupling loop in about an inch or two from that so the coupling loop would
be 13.5in or so to 12.5in not sure which is better. was going to make the
"plate" to hold the cap out of lexan and the "plate" for the connections
back to the receiver. question is how many turns of wire for the AM BCB I am
sure there is a calc for this but I haven't seen it and I wanted to share my
design. Also the rest wood be made from wood the longer pieces.


Scott
KC7WDG

I have a BCB loop constructed on a plywood rectangle 10 1/2" x 14". I placed a 2" peg at each corner. I wound 16 turns of Radio Shack hook up wire around the pegs.

The plywood sheet is mounted vertically on a wood block which acts as a base. I mounted a 365pfd capacitor in the center of the sheet on the side opposite the windings. My Hi-Fi set came with a BCB antenna which consisted of a small plastic hoop about 8" in dia. with 3 turns of wire on it. I use this small loop as the pickup loop for my tuned loop. I attached this 8" hoop to the sheet the centre of my tuned loop. The 8" hoop has a twisted pair about 2' long terminated in spade lugs.

Under normal BCB receiving conditions I have the tuned loop sitting on top of my HI Fi set with the twisted pair connected to the antenna input on the receiver. When I tune the loop to the received station the difference in reception increases a quantum leap.

When I attempt DX reception with this tuned loop and a portable receiver out in the garden (minimize the local noise) I find that the placement of the pickup loop inside the tuned loop provides too much coupling. At first I dismounted the 8" loop and moved it farther and closer by hand to find the optimum coupling which is a balance between best selectivity/signal strength. I soon got tired and mounted one end of a 12" dowel to the plywood sheet and just hung the 8" pickup coil on this 'peg'. I could shuttle it from inside the loop to about 10" away from the loop. What I find is that under certain conditions ... eg separating close stations .... the pickup loop works best hanging on the peg up to 8" away from the tuned loop! I find that the placement of the pickup loop is almost as critical as the tuning of the main loop itself.

One of the advantages of making the tuned loop relatively small is that it is portable. I would not be able to put a 4' loop on the table out in the garden hi. Another thing you might want to experiment with is using your tuned loop with a longwire antenna and ground. I have a longwire available out in the garden and I connected it to one side of the tuning capacitor. A ground wire was connected to the other side. The reception increases a second quantum leap. Again adjust the tuning and coupling for best reception ..... you will be amazed at the daytime reception with this setup. I say daytime because night time reception is completely different with all kinds of different stations coming in on skip. All my BCB DXing is daytime.

So back to your questions:

your loop will be about 13.5x12.5 ..... mine is 10.5x14 and it uses 16 turns.
your pickup loop mounted inside the loop ...... mine is variable and some conditions works best at up 8" away from the loop!

Jim Dunstan
Thunder Bay, ON

Hi,

I got given some poly square plastic stuff and thought hmm I could use this
in a loop somehow and this popped into my mind I am thinking 15 inches on
the outside with wood and the lengths on the inside holding it together that
poly square plastic stuff is 1/2 inch square. So that would make the loop
14.5in square not huge but decent I figure. I was thinking of bringing the
coupling loop in about an inch or two from that so the coupling loop would
be 13.5in or so to 12.5in not sure which is better. was going to make the
"plate" to hold the cap out of lexan and the "plate" for the connections
back to the receiver. question is how many turns of wire for the AM BCB I am
sure there is a calc for this but I haven't seen it and I wanted to share my
design. Also the rest wood be made from wood the longer pieces.


Scott
KC7WDG

Image of Design Is Here >


Any thoughts or suggestions are certainly welcome as this is an idea I
haven't started building yet.

--- In loopantennas@..., "Steve" <Mercxx@a...> wrote:

Good afternoon,
My name is Steve, N4TKP located in Bartow, Florida and I am new to
the list. I am interested in building and experimenting with small
transmitting loops. I have found alot of information so far and the
links here helped me find a couple of tutorials on how to build a
basic one. I am planning on building the first one next weekend. I
have a question though, where can I find the capacitors I need to
take my input power (5 watts for the first and then 100 watts later)
and what should I try first, air variable or a vacumn variable?
Anyway have a great day and I would appreciate any suggestions or
hints that anyone could provide.

73
Steve N4TKP

Hi Steve:

I am new to this list as well. From the date of your post I am a
little bit late before you try your first experiment. I attened a
local 'QRP' group in my home town (Thunder Bay, Ontario) last Thursday
and one of the participants brought a couple of his transmitting loops
and gave a very interesting demonstration. He also gave out a small
DOS computer program (runs fine under windows) that is very helpful in
designing such loops. Just fill in: diameter of loop, diameter of
tubing and power you plan to run and it immediately gives efficincy,
amount of tuning capacitance required, and RF voltage to expect on the
capacitor.

The demonstrator (Vlad) used a small coax pickup loop .... about
8"-10" in diameter.... it was mounted at the top .... right up against
the 3' coil and the capacitor was at the bottom. It was desinged for
20 M. and we used a Elecraft K1 with auto tuner to drive it in the
demo. It worked like a charm and every time he changed frequency and
peaked the loop the K1 (with auto tuner) produced a 1:1 SWR!

I notice from the design program that the RF voltages are reasonable
... eg 1200V or less with 10 watts of drive. When you pump it up to
50 W. the voltages get pretty high! .... with 100 watts you really
need wide spacing on your capacitor hi hi.

This is my first post on this list.

Jim VE3CI

---

Do you Yahoo!?
- 50x more storage than other providers!

When I looked at the end of that cable I only saw 6 wires. Upon
taking the white covering back I see 4 twisted pairs. White and 4
colors. No shielding. All insulated. Telephone? I am sorry and
will try to be more careful in the future.

Probably Category 5 networking cable. The copper wires in it will
work fine.

Just to clear up hopefully one last question-- are you saying to

take

the insulation off of everything and just have bare wire? Or can

I

leave the insulation on the little wires and take off the outside
covering?

Take off the outside covering, and only remove insulation where you
need to twist wires together to make a longer wire, and where you
connect it to the radio.

When I looked at the end of that cable I only saw 6 wires. Upon
taking the white covering back I see 4 twisted pairs. White and 4
colors. No shielding. All insulated. Telephone? I am sorry and
will try to be more careful in the future.

Just to clear up hopefully one last question-- are you saying to take
the insulation off of everything and just have bare wire? Or can I
leave the insulation on the little wires and take off the outside
covering?



--- In loopantennas@..., "Bruce Carter" <brucec@m...>
wrote:

I have a cable that says
MPP/CMP/PCC FT6 -- -- 4/24. Six copper wires. Would that work?

Any
easy way to get the covering off?

I find that rolling the wires with the knife on a meat

cutting block spares my fingers from any chance of cuts.

It is interesting that you have this type of cable. I cannot find

a data sheet for that particular type of cable, but it is possible

that it is a shielded type - it has a braided conductor around the
copper conductors. IF that is

Questions: Can I use a piece of wood instead of cardboard or
styrofoam?

Wood is ideal. I mentioned the others because they are very easy to
find and work with. But if you have woodworking skills - so much
the better. I have several construction articles about making wood
frame loop antennas. Just remember that the tuning capacitor
mentioned in my articles is already inside your radio. You are
trying to match to it.

Is speaker wire too light?

Speaker wire is great - I don't usually mention it because it can be
expensive, and you have to rip the two wires apart to get a single
wire you can wind - or you could always just twist the two wires
together and make one conductor out of it.

I have a cable that says
MPP/CMP/PCC FT6 -- -- 4/24. Six copper wires. Would that work?

Yes, but I recommend ripping the six wires apart, twisting them
together, and making one continuous conductor. 150 feet divided by
6 - you would need 25 feet of the six conductor wire to start with.

Any
easy way to get the covering off?

In the absence of wire strippers, I would take a steak knife and cut
around the insulation in a circumcision fashion, then slide off the
insulation. I find that rolling the wires with the knife on a meat
cutting block spares my fingers from any chance of cuts.

It is interesting that you have this type of cable. I cannot find a
data sheet for that particular type of cable, but it is possible
that it is a shielded type - it has a braided conductor around the
copper conductors. IF that is the case, the braid will make just as
effective an antenna as the wire in the middle. The braid is a
woven metal - and can be easily un ravelled and then twisted to make
a nice end.

Thank you so much guys, Bruce and John. I sort of get a little of
this inductor/capacitor thing now. I am interested in one of the
commercial FM antennas mentioned as the reception on the TV next to
the radio is just slightly compromised now from that splitter. No
biggie, but I have to have an amplifier to get any TV at all. And
never had decent radio in 5 years. But you'all have my hopes up now.

On the AM antenna--- here I thought there was more than just wire
involved! I saw the words ferrite, and induction and freaked I
guess.

Questions: Can I use a piece of wood instead of cardboard or
styrofoam? Is speaker wire too light? I have a cable that says
MPP/CMP/PCC FT6 -- -- 4/24. Six copper wires. Would that work? Any
easy way to get the covering off?

And thanks so much for the ladder concerns, you really warmed my
heart on that. No one would hear the crash out here in the middle of
the big Missouri forest, for sure.
And good guess on the dimmer switches. Both of them are.

Thanks again,
Nancy

--- In loopantennas@..., "Stumm, John C" <jcstumm@s...>
wrote:

Greetings Clueless!
It depends on what you mean by super expensive. CCrane offers a

very nice AM antenna that would serve you well in your outlying area.
They go for a hundred bucks though, (unless you can find one on ebay
for less). You can place the ferrite "head' in a spot that maximizes
signal and minimizes noise. As far as using light switch cover
screws, they tend to be noise magnets, especially if you employ
dimmers. ccrane.com is the address and they offer other antennas as
well. The Justice AM antenna, (as it was formerly known), at $100, is
a lot of bang for your buck. They may offer free shipping also?

Good luck,
John