My location is in the city lot, 1km from the real center of Ljubljana. All antennas are mounted on the parcella dimensions just 29.5 x 15 meters.
Tower #1 - left on the photograph (since 1990) ( lattice steel tower - side length 30 cm (12 inches)) a la ROHN 45, anchored on four sides.
CD-45 rotator, shock absorber, first thrust bearing: Yaesu GS-065 - above shock absorber, second thrust bearing (homebrew, heavy duty) mounted on the top, steel mast OD 2" - 8.5 meters ( 28 ft long).
- 20 - 3 el yagi (old design - W2PV), boom 5,89 m (19´ 4´´) - left tower @ 17,4 m (57 ft)
- 80/75 - inverted vee - on the top of the lattice tower @ 13 m (50 ft)
Tower #2 - right on the photograph (since 1984) ( tubular tower), anchored on three sides (3 x 120 degrees).
- 160 - inverted L - (55 meters ---> 25 m vertical / 30 m horizontal, at the feeding point is added serial variable capacitor 0-1000 pF.)
- (wire on the top of the right tower = 15,5 m steel tubular tower (108 mm (4,25 inches) tube diameter on the top) + 50mm 5m Al tube + fibreglass mast 4,75 m) @ 24,8 m (82 ft) + 1 (one) elevated radial (January 29, 2012). I added second radial (January 26, 2013).
-80 - 1/4 wave vertical + 2 elevated radials (March 7, 2012)
- 40 - 2 element (wire) delta loop with (driver +director) (feeding point is quarter-wavelenght down from the apex - vertically polarized) - hangs on rope between the towers@ 15 m (50 ft). Antenna is fixed to ---> 300 degrees. For receiving antenna on 40 I often use 80m vertical antenna, especially for directions PY, VK, ZL, JA with less noise.
Driver + director, spaced 6.00 m. Driver is tuned on 7100 kc ,
director is tuned 2 % higher --> 7240kc
In "free space"you can cut director wire simply 2 % shorter. But in my case there is impact of surroundings (driven element is just 20 centimeters (8 inches) over the top of concrete garage. That is very closed to the bases of the both loops). So, I tuned director on 2 % higher resonant frequency --> 7240 kc.
Procedure - tuning 2 element delta loop with parasitic elements (my case): driven element + director:
1. Mount two pulleys on 6 to 8 mm diameter rope, distance is 6 meters. In my case, the height of rope was 15 meters. Make driven element loop (wire is 1.5 mm diameter Cu). Make 4:1 transformer (1/4 wawelenght of 75 ohm coaxial cable ). Use transformer to make RF choke (turns of coaxial cable, on (aproximately) 10 centimeters diameter, 20 centimeters long PVC tube). Rope which will carry the element draw through a pulley, then pull isolator of the loop (driven element - apex) to the place.
2. Tune driver to the center frequency (7100 Kcs). (I had measured with SWR meter only - without antenna analyzer). Drop finally tuned antenna element on the ground. (Leave it on the ground when tuning second element - director!)
3. Use the 4:1 coaxial transformer from tuned driver and connect it to the director - just for the tuning procedure. Place second element to the final height and tune it 2% higher (on 7240Kcs). (In case that you haven´t possibility to use wooden support to support heavy RF coaxial choke, match 4:1 coaxial transformer (RF choke) in the down corner (on the one end of the base). When director is tuned, disconnect 4:1 75 ohm coaxial cable transformer and short connect the loop (in my case - short connect PL female connector.)
4. When director is tuned, connect 4:1 75 ohm coaxial cable transformer back to the driven element and mount driven element back to the final height. Connect antenna to the transciever and enjoy DX-ing.
Driver impendance is transformed down with 4:1 transformer --> quarter-wavelenght 75 ohm coaxial cable.
C/f=lambda (wawelenght) --> 299.8/ 7.1 = 42.225 m /4 = 10.556 m x 0.82 = 8.66 m long 75 ohm coaxial cable (I used new CATV cable with foam dielectric. For velocity factor I took 0.82 - I didn´t check it with network analyzer.)
How to make ugly choke for 40 m delta
Cut 1/4 wawelenght 75 ohm cable. In my case 75 ohm CATV cable with foam dielectric (8.66m). Take PVC tube, 10 cm (4 inches) diameter; wound first part of the coaxial cable 6.3 m (21 ft) on the tube; the rest of cable connect to 50 ohm coaxial cable which is connected to HF transciever.
RX antena : 29,5 m long beverage (98 ft) ---> 315 degrees (February 26, 2012)
Former call signs: YU3TAQ, YU3SB, YU3SB/2, YZ3AA, S53AA
October 1977: started in amateur radio coarse in third year of secondary school (17 years old ).
YU3AIJ - (radioclub) My first licence - April 1978 (C licence in ex YU);
YU3TAQ -my first call sign ( B licence in ex YU) - March 1979;
YU3SB (A licence in ex YU) 1986 - ;
YZ3AA - June 26, 1991;
S53AA June 26, 1991 - 1994;
S57W since January 20, 1994 -
Member of Slovenia Contest Club since September 1993; Radioclub Triglav S53APR / S51A & Radioclub Ljubljana S53AJK / S50L.
Icom IC-781, Kenwood TS590S, Yaesu FT-897, ALPHA 77D
TEN-TEC 715i RF Speech Processor
Headset: Heil Pro-Set (with HC-4 microphone), KOSS SB-40
Vector Network Analyzer (May 5, 2015) N2PK (Many thanks to Robert S57AW for advices and support and Joze S51VJ for help with assembling VNA!)
SW: Logger 32, N1MM+
9A/S57W - August 22 - August 29, 2015 from NW Croatia (FT-897 + windom antenna at 10 meters).
7635987 Last modified: 2016-10-16 19:10:42, 15212 bytes
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