In article ,
David wrote:

RHF wrote:
On Dec 23, 1:27 pm, Telamon
wrote:
In article ,





David wrote:
Telamon wrote:
In article
,
Telamon wrote:
In article ,
David wrote:
RHF wrote:
The Verdict {One Man's Opinion} : Magnetic Longwire Balun Is Too
Expensive
http://www.hard-core-dx.com/nordicdx.../magbalun.html
-by- Alan Johnson
-source- Hard-Cord-DX website :http://www.hard-core-dx.com/
The Most Common Antenna Type
Randon Wire Antenna Problems
Enter the Balun
The Magnetic Longwire Balun (MLB)
In the Laboratory
After Four Rainy WeekEnds
I also did A-B Comparisons
* The Results
The "Resistance" Curve for the MLB
The N8KDV Transformer
A-B Testing was very Revealing.
* Recommenation
How Essential is a Perfect Match?
Based on Price and Performance
The MLB Definitely Wins
Originally Published in the NASWA Journal - July 1992
-by- Alan Johnson [N4LUS]
Magnetic Longwire Balun (MLB)
http://www.universal-radio.com/catalog/sw_ant/1484.html
http://www.dolstra.nl/Z&L-amateur/AN...tems/MLB_1.JPG
http://www.remeeus.eu/english/hamradio/mlb.htm
http://ham.srsab.se/graphics/antennas/mlbII.jpg
-by- RF Systems - MSRP Price ~ $60
Alternative "MLB" - MLB-1 Magnetic Longwire Balun
http://www.palomar-engineers.com/MLB-1/mlb-1.html
-by- Palomar Engineers - MSRP Price ~ $50
NOTE - While the 'N8KDV Transformer' is presently Not Available.
WinRadio does offer the LWA-0130 Long Wire Antenna Adapter
http://www.grove-ent.com/WR0130.html
http://www.winradio.com/home/lwa.htm
http://www.winradio.com/home/ax05e.htm
-by- WiNRADiO - - MSRP Price ~ $40
READ - Good Deal on 9:1 Matching Transformer
http://groups.google.com/group/rec.r...7e40978fdc32ac
0
-by- William Fieldstone
More WinRadio LWA-0130 Long Wire Antenna Adapter Postings
http://groups.google.com/group/rec.r...77d380609eec59
2
http://groups.yahoo.com/group/Shortw...na/message/230
iane ~ RHF
.
[D]iane,
The point is to keep the feedpoint Z below the transmission line Z.
What's the advantage of the feed-point Z being below the transmission
line Z?
OK I'll answer it. None.
Less pinching in the midriff...
There's a rule.

? OK here is the rule, when you have an impedance mismatch
? by some ratio it does not matter which system element is
? higher or lower so for example if the coax transmission
? line is 50 ohms and the antenna impedance is 25 or 75 ohms
? the result is the same amount of reflected power.
? 25 ohms and 75 ohms are equivalent in this regard.
? One is not a better situation than the other.

Telamon,

Wouldn't it be the Ratios :

25 Ù Antenna to 50 Ù Coax ~ 1 : 2

50 Ù Coax to 100 Ù Antenna ~ 1 : 2
-vice- 50 Ù Coax to 75 Ù Antenna ~ 2 : 3 (1 : 1.5)

~ RHF

- Take an extreme case of this where you have either a short
- or the coax is open with nothing connected on that end.
- In either case if you were to send RF power to the open
- or short end of the cable you would have 100% reflected
- power. The returned phase of the that power would be 90
- degrees different though.
-
- This is different situation then DC current where the open
- and short would have very different consequences.


Low goes into high better than high goes into low. Reflected power does
no harm in a receive antenna. Try using your 300 Ohm antenna with a 50
Ohm transmission line. Then try using a 50 Ohm antenna with a 300 Ohm
transmission line. Which will receive better?

Neither will be better. If you don't understand this look up VSWR and
study that topic.

Of course there is not enough power to hurt any part of a receive
antenna or transmission line but it harms your reception.

When it comes to RF all that matters is whether two components match and
if they don't how far apart they are in impedance. It does not matter
which is higher than the other; the results will be the same reflected
power. It's a simple rule that applies to many a physics problem not
just antennas and transmission lines such as light through a prism or
light passing from air to water.

--
Telamon
Ventura, California