= = = Richard Clark wrote in message
= = = . ..
On 13 Nov 2004 20:41:52 -0800, (RHF) wrote:
JK, RC and CM,
I want to Thank Each of You for your replies to this question.
Note: I am only talking about a SWL "Receive Only" Antenna here.
Hi OM,
As were the answers (with possibly one exception).
I suspect that may be one reason that this Far-End Loaded AM/MW
Coil may work is the fact that the RF Systems EMF Antenna is
'only' Sixteen Feet (16') Long; and the Two Inch to Three Inch
(2"-3") Ferrite Rod at the End of the Wire Antenna Element does
have some 'measurable effect' on improving the AM/MW Frequency
Band performance of such a short Antenna.
- Relative Size may be the Controlling Factor for this 'unique'
small Antenna
? ? Would this 'trick' work with a Larger {Longer} SWL Antenna ? ?
Let's approach this from the usual perspective. Many SWLrs posting
here already have the ferrite antenna in their receiver and come here
for a boost in signals. The fact that it is so easily accomplished by
the addition of that same 16 feet of random wire tossed across the
living room rug would suggest just how much contribution is found in
the ferrite antenna.
My target receivers are my Kenwood R-5000, Icom IC-R75, and
Grundig Satellit 800 M. Note with the Grundig Satellit 800 M
when the SO-239 is switch on to use the External Antenna the
'internal' AM/MW Ferrite Rod Antenna is disconnected.
Let's put some numbers to it. With the ferrite antenna a DX station
comes in S3, replace it with the wire and it climbs to S7. So, if we
start with just the wire antenna with the same signal at S7, and
adding the ferrite to pump up da volume to S7+ would this be worth $95
to you? What if by simply adding 6" more wire to the 16 feet gave you
that same +?
Not worried about the cost since this would be a 'home-brewed'
Antenna with parts I already have.
Looking to add a little more signal to the AM/MW Band area for
improved Weak Signal DXing from the Inverted "L" Antennas.
As a product, it is incredibly cheesy to boot. Look at that clunky
pl259 at the end of rg174. C'mon now, are we talking about your
granddad's RCA Victor this sucker is going to plug into? That and the
lead-in is only 16 feet in its own right? How much profit would be
lost to give you a decent length of wire and lead-in?
My more specific point of interest would be in whether using a
Ferrite Rod with the Wire Antenna Element Wrapped as a AM/MW
Coil around it would have some meaningful effect on a Horizontal
Random Wire Antenna that was 75-100 Feet long.
- For a Horizontal Random Wire Antenna ?WHY? 'place' the
Ferrite Rod at the Far-End of the Wire Antenna Element ?
- Why not 'place' the Ferrite Rod near the Feed-Point-End ?
- Why not 'place' the Ferrite Rod near the Middle ?
- Why not 'place' the Ferrite Rod near the slightly Off-Center
38%/62% like a Windom ?
This at least suggests a more practicable study. Loading coils don't
do very much without some form of capacitance above them to draw the
current. Putting a coil at the top is a fruitless exercise. It may
offer to "tune" but it sure won't sing.
73's
Richard Clark, KB7QHC
RC,
I have the two Inverted "L" Antennas and about a dozen 10mm X 200mm
Ferrite Rods to play with. So for me it is a matter of De-Rigging
the Antennas; winding the Antennna Wire on the Ferrite Rod; and
Re-Rigging the Antennas.
Doing a dry run with an extra piece of Antenna Wire; I can get
about Nine Turns per Inch; which would be 63 Turns uniformally
wrapped evenly over 90% of the Ferrite Rod.
So my 'focus' is on a "Low Noise' Inverted "L" Antenna that is
100 Feet long. Placing the Ferrite Rod at the "Top" of the
Vertical Leg where the Antenna Wire Element transitions from
Vertical to Horizontal. Rig the Antenna Wire Element with 33
Feet Up to the Ferrite Rod AM/MW Ferrite Coil and then have 67
Feet Out to the Far-End. Would this possibly work any better
then having the Ferrite Rod and Coil at the Far-End ? and Why ?
In my 'imagination' for the AM/MW Broadcast Band; the Vertical
Up-Leg would act like an Omni-Directional "Tuned" Vertical Antenna
(since the Ferrite Rod would be Vertical); with the Horizontal
Out-Arm of the Antenna acting like a Top Hat for the Vertical.
Then at the Shortwave Frequencies the 'effects' of the Ferrite
Rod would become less and the Antenna would simply act as a
normal SWL'ers Inverted "L" Antenna.
Now here is another thought; would having the Ferrite Rod with the
Antenna Wire wrapped around it at the Far-End of the Horizontal
Antenna Element cause the AM/MW Broadcast Band reception to be
Directional 'Off-the-Sides' of the Inverted "L" Antenna ? ? ?
in search of some ideas and answers ~ RHF
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