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WD8DSB Pennant RX Antennas (location near Indianapolis Indiana)
Antennas aimed as follows :
Ant #1 = 40°
Ant #2 = 160°
Ant #3 = 300°
Antenna Dimensions : Each pennant is 51.6% the size of a full size pennant (X = 14.96 ft, Y = 7.22 ft, R = 15.39 ft)
Termination Resistors : 800 to 820 ohms
Pre-amp on 160 meters : W1FB preamp (slightly modified for extra RF protection to prevent damage when transmitting, see bottom of page for details).
Note: In late 2017 I started using a single W7IUV preamp on 160 meters with my small pennants (gain approximately 21 dB), and it appears to work well (it provides just enough gain).
Pre-amp on 40 meters : W7IUV preamp (http://sites.google.com/site/rxpreamps/)
EZNEC Demo predicted patterns (Real Ground, Elevation Angle = 31 Degrees)
Black = 40° antenna
Red = 160° antenna
Green = 300° antenna
Picture of antenna selection relay box located at the feedpoint of the point fed pennants (using original FT-114-77 transformer).
Relays are part number OMI-SH-212L
FT-114-77 replaced by BN-73-202 Binocular Core Transformer (see transformer tests below).
Feedline Note: I'm using RG58 coax that has braid as well as foil shield which I purchased from The Wireman and the part number/identification is as follows: Ultra Flexible Lo-Loss RG58 P/N 129FF
WD8DSB Pennant Antenna Switching System Schematic
(Note : I actually use a 2 pole 6 position rotary switch in place of the DPDT center off toggle switch, and I use 1N4007 diodes for the 4 diodes shown below, Relays OMI-SH-212L)
Below is my proposed Bias Tee network design for replacing the individual control cable
(concept based on a Bias Tee design by AD5X)
Note : I recommend that the wall wart power supply shown above be well regulated (low ripple when under load)
(Note: on Aug 19, 2017 Jim Profitt (NM8O) reported that he built my 3 pennant system using the Bias Tee circuit shown above, and that it "works well".)
Below is my proposed Bias Tee concept using the MFJ-4116 which is a commercially available Bias Tee
Updated Transformer Test Results using final version of the WD8DSB Antenna Analyzer 14AU13
1K ohm resistor connected to transformer secondary, transformer primary connected direct to analyzer (no feedline).
FT 114-77 Toroid core (Primary = 5 turns, Secondary = 20 turns)
R = 57 ohms, X = 18 ohms, SWR = 1.43, Freq = 1.8 Mhz
R= 58 ohms, X = 34 ohms, SWR = 1.89, Freq = 3.5 Mhz
R = 66 ohms, X = 70 ohms, SWR = 3.26, Freq = 7 Mhz
R = 81 ohms, X = 106 ohms, SWR = 4.80, Freq = 10 Mhz
R = 120 ohms, X = 168 ohms, SWR = 7.39, Freq = 14 Mhz
R = 183 ohms, X = 238 ohms, SWR = 10.02, Freq = 17.5 Mhz
One BN-73-202 Binocular core (Primary = 3 turns, Secondary = 12 turns)
R = 59 ohms, X = 0 ohms, SWR = 1.18, Freq = 1.8 Mhz
R = 57 ohms, X = 0 ohms, SWR = 1.14, Freq = 3.5 Mhz
R = 53 ohms, X = 0 ohms, SWR = 1.06, Freq = 7 Mhz
R = 49 ohms, X = 0 ohms, SWR = 1.02, Freq = 10 Mhz
R = 43 ohms, X = 0 ohms, SWR = 1.16, Freq = 14 Mhz
R = 38 ohms, X = 0 ohms, SWR = 1.32, Freq = 17.5 Mhz
Two BN-73-202 Binocular cores (Primary = 3 turns, Secondary = 12 turns)
R = 60 ohms, X = 0 ohms, SWR = 1.20, Freq = 1.8 Mhz
R = 59 ohms, X = 0 ohms, SWR = 1.18, Freq = 3.5 Mhz
R = 55 ohms, X = 0 ohms, SWR = 1.10, Freq = 7 Mhz
R = 50 ohms, X = 0 ohms, SWR = 1.00, Freq = 10 Mhz
R = 44 ohms, X = 0 ohms, SWR = 1.14, Freq = 14 Mhz
R = 39 ohms, X = 0 ohms, SWR = 1.28, Freq = 17.5 Mhz
Note : measured Impedance on the primary should have been R = 62.5 , X = 0 with an SWR = 1.25, so the BN-73-202 performs much better than the 114-77.
Repeated the above binocular core test using a 800 ohm resistor connected to the secondary, and obtained the following results :
One BN-73-202 Binocular core (Primary = 3 turns, Secondary = 12 turns)
R = 47 ohms, X = 0 ohms, SWR = 1.06, Freq = 1.8 Mhz
R = 47 ohms, X = 0 ohms, SWR = 1.06, Freq = 3.5 Mhz
R = 44 ohms, X = 0 ohms, SWR = 1.14, Freq = 7 Mhz
R = 42 ohms, X = 0 ohms, SWR = 1.19, Freq = 10 Mhz
R = 38 ohms, X = 0 ohms, SWR = 1.32, Freq = 14 Mhz
R = 36 ohms, X = 0 ohms, SWR = 1.39, Freq = 17.5 Mhz
(theoretical should have been R = 50.0, X = 0.0, SWR =1.0, so very satisfied with the results)
Front to Back Ratio Versus the arrival angle (elevation angle) of the signal is shown in the chart below
Youtube video showing actual recording of AA1K and directional properties of my pennant array : http://www.youtube.com/watch?v=TWlBy5ypMIU
Youtube video showing actual recording of W5XZ and directional properties of my pennant array : http://www.youtube.com/watch?v=BON0VcfD_Xo
Typical skywave signal to noise improvement on 160 meters using my pennants compared with my TX vertical
0 to 1500 miles = 6 dB (and often much more for stations within 200 miles depending on NVIS)
2000 miles = 3 dB
4000 miles or more = 1 to 3 dB (Note : most often 2 dB, but sometimes only 1 dB) Revised Jan 25, 2016
(The above numbers are just approximations based on many hours of comparison testing of my pennants versus my TX vertical antenna on 160 meters.)
W1FB preamp modifications
1) Added back to back diodes (1N914) across the output of the preamp to clip any strong RF that might back feed into the preamp via the preamp output port when
I transmit (this also provides additional protection to the receiver). 2) Added a 100uH RF choke to the +12 volt supply line inside the preamp. 3) Added back to back diode protection directly to the front end of the MC1350 by adding a 0.1 uf cap between the existing 100pf cap (C5), and pin 4 of the MC1350, and
then installed back to back diodes (1N914) from the junction of these two caps to ground.
4) Added series diode(1N4007) in line with the +12 volt supply for reverse polarity protection.
Full details of my W1FB preamp modifications can be found on the following website : http://sites.google.com/site/w1fbpreamp/
Webpage created and maintained by Don Kirk (wd8dsb)