Vy Low Rx Dipole / AO-Journal p910

26-04-2016

100 / 400 ohm transformer conditionned

Matched antenna

Default : 0.951

Folded dipole
Myths
by W8JI

Folded dipole

4/1 transformer
100 ohm = 3 turn
400 ohm = 6 turn

100 ohm = 3 turn

9/1 transformer
100 ohm = 3 turn
11.11 ohm = 1 turn

Test tool
11.11 ohm Dummy Load 1.5w
2x33 & 1x27 in parallele

Poor
ground
effect

Poor
ground

OH3GGQ

Balun 1/4

Balun 1/1

|--------------------->----------------------Flip back 50 cm ----------------->------------------> |

20m tag

Matching Transformer calculator

Ferrite Binocular core Amidon BN-73-202 ----->

Basic 1/1 transformer
50 ohm = 2 turn

Insertion loss      0.1dB
               (HP-141)       1.8 - 3.8 MHz

  Return loss  21dB @ 1.8 MHz
        (HP 8721A)  24dB @ 3.8 MHz


--------------

--------------

Step 4 : Folded Flat Top Dipole

Step 1 : Beverage ? What else ?

Step 3 : Poor ground

Problem Solution ?

Step 2 : Flat Top Dipole

Step 4 : Matching

Background database

Cette antenne a t-elle une utilité ?

C'est une autre histoire... QRX

Test Tool

Frequency range: 0.1 to 600 MHz - AA-600
                            0.1 to 1000 MHz - AA-1000
                            0.1 to 1400 MHz - AA-1400

Frequency entry: 1 kHz resolution

Measurement for 25, 50, 75 and 100-Ohm systems

--------
Line to shack
> 200m

Twinaxial 100 Ohm
RG-22   or  IBM 7362211

K3LR
Low height full size dipoles for 160 and 80 meters at 5 meters high
It all depends on what other antennas you have.
I have had up a 14 ft high 1/2 wave dipole on 160 for many years.
(4.27m soit 2.13m sur 80m)
It has always impressed me

as a high angle antenna which limits its prime effectiveness to gray line use.
I also use it in tandem with other antennas and the MFJ receive antenna noise canceling
W8JI magic box (also an effective antenna phasing unit).

My low dipole's claimed fame was a sunrise QSO
with KH2. No other antenna (1100' beverage, vertical array, etc.) could
hear the KH2, but he was 569 on the low dipole.