Hi Top-banders
I just got this skype IM for Ilian T6LG and I would like to congratulate Ilian for his dedication on all aspects of Ham radio. hi Jose [12:02:50 PM] Ilian: My log is already uploaded on LoTW and ClubLog [12:03:23 PM] Ilian: 1394 QSO on 160m [12:04:15 PM] Ilian: more than 1200 QSOs after RX antenna installing [12:05:02 PM] Ilian: about 150 QSOs without RX antenna for more than 2 months on the air [12:05:57 PM] Ilian: 1200 QSOs made with RX antenna for 1 month and 10 days [12:06:49 PM] Ilian: 68 DXCC worked on 160m during the all operation [12:07:49 PM] Ilian: about 40 countries worked after RX antenna installing within 1 month and 10 days [12:09:49 PM] Ilian: 3865 QSOs on 80m during the all operation, about 2500 worked after RX antenna installing [12:10:24 PM] Ilian: 112 DXCC worked on 80m for whole period [12:11:54 PM] Ilian: about 50 new DXCC worked after RX antenna installing for a month and 10 days [12:13:36 PM] Ilian: http://t6lg.com/?page_id=221 [12:14:05 PM] Ilian: you can see all statistics here [12:15:57 PM] Ilian: Thank you, Jose! Here a little tail about this high performance RX antenna. Ilian was operation in a military campus, you can see the pictures on his website www.t6lg.com The noise level was unbearable for low bands, Ilian was not able to hear even the strong European station but Ilian had a good signal on low bands. I worked him on 80m back in October and start chatting with him on skype. I proposed a flag antenna to improve his RX capabilities. The problem with most field station is lack of good ground, this issue makes a very complicated situation with common mode noise everywhere, from the coax cable feeding the inverted V to the AC wire system and power generators, and other antenna cables. There is not a simple way to ground the receiver, every wire connected to the radio became part of the antenna system. The solution was a system , not only a simple flag antenna. Ilian radio is a FT897 that does not have a separated RX port. I send him a DX Engineering RTR-1 Receive Antenna Interfaces RTR-1, that switch was necessary to keep high isolation between the RX antenna and the TX antenna. The flag antenna has low gain and I sent Ilian a preamp made by Gary KD9SV, a FET follower design with high IP3. The parts for the antenna was very simple, a 9"1 balun and a 910 ohms resistor, and a 100 to 75 ohms BALUN to feed the preamp. The key component here was the CAT 5 single twisted pair to feed the flag antenna without any common mode noise pickup (it is necessary to strip the CAT5 and separate each of the 4 pairs), a coax cable won't work in high noise environment, even with a killer choke the ground does not help to stop the common node noise. That was not the first time a twisted pair saved the day, two years ago I suggested Rolf PY1RO a similar antenna fed with twisted pair that worked very well, bringing the noise to zero in a s9+20 noise environment. The Delta Flag antenna built by Ilian was very similar the RX antenna used by FO0AAA and described by K6SE. It is a triangle antenna (any size works) with 24 ft base and hung from a single point that allows Ilian to rotate the antenna. Actually this feature was very desired, Bill W4ZV educated Ilian about long path propagation on 80m and he made several very happy campus on West Coast listening South for Long Path on 80m. This antenna can be used on most of DX expeditions with no place for beverages, a simple RX antenna made with CAT5 wire can be a high performance antenna and a difference between no or few QSO's and few thousand QSO;s A single flag is not the best antenna you can build, the RDF is modest but the secret is how to implement this antenna avoiding common mode noise, a simple CAT 5 twisted pair can make a huge difference. I see no reason for a DX expedition to complain about noise on low bands, CAT 5 can be found anywhere and it is vey light. P.S. I was not able to work Ilian on top band, never had the spotlight. Regards Jose Carlos N4IS Delta RX Antenna used by FO0AAA from Earl, K6SE on June 1, 2000 View comments about this article! Several subcribers inquired about the Delta 160-meter receiving antenna used at FO0AAA. It is a close relative of the Pennant and Flag antennas, which are ground-independent relatives of the Ewe. The Delta is a modification of the "delta-shaped Ewe loop" shown in figure 7-66 on page 7-51 of ON4UN's new Low-Band DXing book. I took John's Delta-Ewe and, with the feedpoint and termination located at the bottom corners of the triangle, I used EZNEC to optimize the design for best F/B and zero reactance at 1.830 mHz. This is the design that was built by ON4UN for use by FO0AAA. It is a delta loop-shaped antenna with a 28-foot (8.537m) bottom horizontal wire and the apex 17 feet (5.183m) above the bottom wire. That means there is a total of about 72 feet (21.951m) of #14 AWG wire in the triangular loop. The EZNEC design had the bottom horizontal wire 3 feet (0.915m) above ground, therefore the apex was 20 feet (6.096m) above ground. It is a ground-independent antenna, without the ground-related shortcomings of the Ewe. The termination resistor, which goes in one of the bottom corners of the loop, is 950 ohms non-inductive. The feedpoint is at the other bottom corner and the feedpoint impedance is 950 ohms with zero reactance at 1.830 mHz. An impedance matching transformer such as those previously described on the Topband Reflector for use with the Pennant or Flag should be used with the Delta antenna. The F/B ratio in the EZNEC model is greater than 40 dB and the cardioid pattern directivity of the antenna is in the direction of the feedpoint end of the antenna (the same as with the Pennant, Flag, or Ewe). The gain of the antenna is about -34.5 dBi, so a receive preamp should be used with the antenna. The primary reason this design was chosen by the FO0AAA team was that it was an easily-erected and easily-rotated directional receiving antenna. Only one support at the apex is needed (which must be non-metallic). The bottom corners of the antenna can be attached and pulled taut with rope to tent stakes driven into the ground. To change directions, it is a simple matter to relocate the tent stakes to the desired direction and re-attach the corners of the antenna. Unfortunately, this design was done too late to make it into an article about Flags and Pennants I wrote for QST (which will probably appear in the July 2000 issue). 73, de Earl, K6SE _________________ Topband Reflector
