Improving AM Broadcast Band reception

Improving AM Broadcast Band reception

Post by Dxluv » Wed, 03 Mar 2004 17:44:23

Quote:>but inside this
>place, even the 780 doesn't do well, because of all the QRM..

Unbelievable,  though I believe you. ;-)  I've had that 780 in places and
offices and one home that was absolutely he** for RF but the ole' GE P-780
handled it as it always has.

*I think* the reason that rat sgack loop doesn't work with the GE P-780 is that
it is so well made that it doesn't need a loop,  all my other receivers get
some kind of lift from my loop except that particular piece.

That was what I read and was told by an old timer when he saw the 780,  he said
"wow,  that battleship brings back memories,  where in the world did you get
one of them." lol  We must have say out there for three hours listening to that
radio and talking,  he's in his 90's and just a super guy and he really thinks
highly of that radio.

BTW,  thanks for being my 'dealer.' ;-)  No....no...guys....no *** involved.

 
 
 

Improving AM Broadcast Band reception

Post by Mark Kei » Thu, 04 Mar 2004 16:05:15



> The shield is electrostatic and would only help against local noise
> (example - in the room computer) being the pickup loop.

Yes, And I could tell no real difference from it to a unshielded loop.
This assumes the unshielded loop is fairly well balanced though.

Quote:

> If you had an un-tuned broadband amplified single turn shielded loop
> compared to one that was not shielded then you would expect to see a
> difference.

I would think so. But so far I don't really see a drastic difference.

Quote:

> Loop antenna is a broad term.
> Here are some features:
> 1. Small or large compared to the received wavelength.

A small loop is directional inline with the windings. A large loop,
broadside to the windings.

Quote:> 2. Shielded or not.

Again, this is debatable as to the effectiveness...I consider it an
option.

Quote:> 3. Single or multi turn and shape type example - pancake or solinoid.

A pancake coil is directional broadside to the loop. A solenoid,
inline with the loop. Or so I've read...So far, almost all of my small
loops are solenoid type. I have thought about planting a big pancake
coil on a door though...

Quote:> 4. Tuned or un-tuned.

All small passive loops should be tuned. At the least, using the self
resonant freq. With the cap, lower in freq...

Quote:> 5. Several ways to couple them to the receiver.

I use normal coupling loops, both shielded, and unshielded as a test.
I see no difference in results..I don't use preamps. Don't need em...

Quote:

> Now you can mix and match the 5 above into many possibilities all with
> different tradeoffs.

Thats what I'm doing here, but with not always the results I want...
IE: I made a 45 turn LW loop that I hang up against my usual 16 turn
MW loop. I used the same cap for each loop, by using a switch. It
worked great on both "bands". Didn't mess up the MW loop. So then, I
decided to wind a LW loop on the same frame hoping for the same
results. The LW worked fine, but the MW was detuned. So I just now
ripped all the LW turns back off and will go back to the previous
method with a bit more separation between the windings. I'm rigging
mine up to cover from about 150hz to 2000 hz in two steps. "coils".
This lets me use the same cap for both, and I don't have to tack on
extra fixed caps for LW. But I still want to build some type of
unidirectional rotatable small loop. In messing with the LW loops, I
have discovered something about my radio I hadn't noticed.
"IC-706mk2g". Although it tunes down to 30 cycles, the radio goes
pretty dead below about 150 cycles. Not the greatest LW radio in the
world for real low freq's...:( It's ok from about 175 hz, up.. MK
 
 
 

Improving AM Broadcast Band reception

Post by Mark Kei » Thu, 04 Mar 2004 16:16:36


> >I agree....My homemade loops are better for my uses than what you can
> >buy. I can design any feature I want, and generally they are bigger
> >and deliver more voltage than most storebought.

> MK,
> would you mind emailing me?  I have a question.

Actually, I prefer to keep it on the NG, but you can e-mail me if you
want.
The main reason I like to keep it on the group is if I lay a clam,
someone will usually correct me...   MK
 
 
 

Improving AM Broadcast Band reception

Post by Dxluv » Sun, 07 Mar 2004 19:40:54

Quote:>The main reason I like to keep it on the group is if I lay a clam,
>someone will usually correct me.

huh, OK.
 
 
 

Improving AM Broadcast Band reception

Post by Mark Kei » Mon, 08 Mar 2004 09:03:37


> >The main reason I like to keep it on the group is if I lay a clam,
> >someone will usually correct me.

> huh, OK.

Yea...:(  As an example, the other day I said a pancake loop's nulls
were at right angles compared to a solenoid loop. The reason I said
this, was I saw it mentioned on a web page somewhere. But after
thinking about it more, I'm not so sure that is correct. Seems to me,
they should act the same as a solenoid loop as far as null direction,
being they are both "small loops". But I'm not sure...All my current
loops are solenoid. Any comments from any pancake loop owners? Are the
nulls broadside to the loop, as in a solenoid loop? Or opposite?
I do know a ferrite bar antenna is opposite from a solenoid loop. BTW,
I just built a new bigger loop yesterday. It's a diamond loop appx 43
inches per side.
It's 5 ft across at the spreaders. Built it from PVC and is a simple
cross frame. I have it in the room with me, and it's rotatable on a
stand like my 16 inch loop. It's working real good so far. It does
give a lot more voltage than the small loop. About 2 s units worth on
average. Will be good for weak signals in quiet cdx. Good for LW too,
being it's pretty big.  Started out with 7 turns, but ended up with 5.
I couldn't tune 160m at first. I'm using two variable caps, one appx
850 pf?, and one that is maybe 50 pf or less full mesh, and two sets
of fixed capacitance to tune from 250 cycles to about 2.5 mhz. On the
high end, I'm using very small capacitance values. In fact, I had to
take a 3 150 pf?? "guessing" piece variable, and only use one section
for those upper freqs. The balance came out as good as my other one,
and about equal or better nulls. Using a one turn coupling loop inside
the tank coil. The nulls seem even and the same either side. Thats
what you really want to see. If they slew off from actual direction,
or are unequal , you know you have a balance problem.
MK
 
 
 

Improving AM Broadcast Band reception

Post by Zach Lian » Wed, 10 Mar 2004 03:39:09

RHF , have you tested   this antenna  over a australian loop?

MY asutralian loop ( ie a 1 x 1 sqm x 7 woulnds ) ofered possibly more
than 30 db gain [i have not any ability to measure the signal level !)
] over the standard radio loop no matter which is ( degen 1102 , Khibo
C300 , Bolong  and other poket  radios I use)
I could listen in mid day ( 3-5 LT) in Thessaloniki N Greece  even a
french station on ca. 600 kHz with 500  kW


Quote:>"B
>BA,

>Check-Out the "Select-A-Tenna" (SAT) Model 541-M  

>SAT=>  http://www.selectatenna.com/

>"This is the second generation of Select-A-Tenna.  It has the
>same intrinsic +30dB signal strength improvement and features
>as the basic 541 model.  In addition, a jack on the front panel
>allows the unit to be connected to either an outside long wire
>and ground, or as an alternative,  directly connected to a
>radio's antenna and ground terminals when the radio has no
>internal ferrite rod antenna."

>iane ~ RHF

>.

>.

 
 
 

Improving AM Broadcast Band reception

Post by Zach Lian » Sat, 13 Mar 2004 00:49:38

RHF , have you tested   this antenna  over a australian loop?

MY asutralian loop ( ie a 1 x 1 sqm x 7 woulnds ) ofered possibly more
than 30 db gain [i have not any ability to measure the signal level !)
] over the standard radio loop no matter which is ( degen 1102 , Khibo
C300 , Bolong  and other poket  radios I use)
I could listen in mid day ( 3-5 LT) in Thessaloniki N Greece  even a
french station on ca. 600 kHz with 500  kW


Quote:>"B
>BA,

>Check-Out the "Select-A-Tenna" (SAT) Model 541-M  

>SAT=>  http://www.selectatenna.com/

>"This is the second generation of Select-A-Tenna.  It has the
>same intrinsic +30dB signal strength improvement and features
>as the basic 541 model.  In addition, a jack on the front panel
>allows the unit to be connected to either an outside long wire
>and ground, or as an alternative,  directly connected to a
>radio's antenna and ground terminals when the radio has no
>internal ferrite rod antenna."

>iane ~ RHF

>.

>.

 
 
 

Improving AM Broadcast Band reception

Post by RH » Mon, 22 Mar 2004 18:50:18

ZL,

I have made several Loop Antennas in the One Meter Square Size range.  

IIRC:  Two Loops one smaller and the other larger; that are
built with the same care and materials would have the same
'relative' Gain with respect to their Peak Signal and ability
to Null a Signal.  (Both Loop Antennas would have about the
same "Q" Number.)

AUSTRALIAN ONE METER SQUARE Loop Antenna = 10,000 cm Sq.
A larger Loop Antenna has a greater Signal Capture Area and
usually this results in a higher Signal Outout.
*  The Australian 1 Metre Loop from Hard-Core-DX.Com  
- by Werner Funkenhauser
http://www.hard-core-dx.com/nordicdx/antenna/loop/1mloop.html
*  Bigger Image of the "Australian 1 Metre Loop"
http://www.hard-core-dx.com/nordicdx/antenna/loop/rnloop1.gif
*  The One Meter (3-4Ft) Loop Antennas all perform really good,
but they are big and need a lot of space to position them and
operate them.

SELECT-A-TENNA [Twelve Inch Round] Loop Antenna = 730 cm Sq.  
A smaller Loop Antenna has a small Signal Capture Area and
usually this results in a small Signal Outout.
*  Check-Out the "Select-A-Tenna" (SAT) Model 541-M  
SAT=>  http://www.selectatenna.com/
*  The smaller Loop Antennas like the Select-A-Tenna perform
very well, plus they are easier to use and simply more portable.  

THE NUMBERS:  Based upon the above two numbers for the
Australian One Meter Square Loop Antenna -=V=- the
Select-A-Tenna [Twelve Inch Round] Loop Antenna the relative
areas of the Loops are ruffly (10,000/730) 14 to 1.  What this
means that the Australian One Meter Square Loop Antenna will
have a Higher Signal Level (Output) and because of it's
greater Signal Capture Area this would result in less apparent
fading of the signal when using it vice the Select-A-Tenna.

RANGE:  Estimated usable DXing Ranges of these two Loop Antennas.  
*  Australian One Meter Square Loop Antenna = 2775 Km (1750 Miles)
*  Select-A-Tenna [Twelve Inch Round] Loop Antenna = 750Km (475 Miles)

IMPROVING THE "Q" OF THE LOOPS:
*  One thing that can 'improve' the "Q" of a Loop Antenna is to
Replace the wire used in the Loop with LITZ Wire.  
*  Another thing is to reduce the "Spacing" between the Loop Turns.
The Australian One Meter Square Loop Antenna plans call fo 12mm
(1/2") Spacing you mite try reducing this to 9mm (3/8").

LOOP ANTENNA HELP:
*  "Loop Antenna Information Forum" eGroup on YAHOO !
LOOPS=>  http://groups.yahoo.com/group/loopantennas/
*  "Ferrite Rod Antenna Experimenters" eGroup on YAHOO !
http://groups.yahoo.com/group/FerriteRodAntenna/
*  "Shortwave SWL Antenna" eGroup on YAHOO !
SWL=>  http://groups.yahoo.com/group/Shortwave-SWL-Antenna/
.
.
iane ~ RHF
.
Some Say: On A Clear Day You Can See Forever.
http://groups.yahoo.com/group/Shortwave-SWL-Antenna/message/502
I BELIEVE: On A Clear Night...
You Can Hear Forever and Beyond - The Beyond !
.
.


> RHF , have you tested   this antenna  over a australian loop?

> MY asutralian loop ( ie a 1 x 1 sqm x 7 woulnds ) ofered possibly more
> than 30 db gain [i have not any ability to measure the signal level !)
> ] over the standard radio loop no matter which is ( degen 1102 , Khibo
> C300 , Bolong  and other poket  radios I use)
> I could listen in mid day ( 3-5 LT) in Thessaloniki N Greece  even a
> french station on ca. 600 kHz with 500  kW


> >"B
> >BA,

> >Check-Out the "Select-A-Tenna" (SAT) Model 541-M  

> >SAT=>  http://www.selectatenna.com/

> >"This is the second generation of Select-A-Tenna.  It has the
> >same intrinsic +30dB signal strength improvement and features
> >as the basic 541 model.  In addition, a jack on the front panel
> >allows the unit to be connected to either an outside long wire
> >and ground, or as an alternative,  directly connected to a
> >radio's antenna and ground terminals when the radio has no
> >internal ferrite rod antenna."

> >iane ~ RHF

.