Pennant, Flag, Delta receiving antenna notes

• Pennant, Flag, and Delta antennas, in order to receive low angles, need to be decoupled from ground to achieve ground independence.
• Ground independence requires common mode signal decoupling of the coax cable shield. This is done by minimizing the matching transformer primary to secondary capacitance. A BN-73-202 binocular core, with low capacatance windings, can provide the needed isolation.
• As per Earl, K6SE (sk). The Delta receiving antenna has been the favorite of many DX-peditions, requiring only one non-metallic support at the top apex. The lower corners are typically fastened with ropes to tent pins that can be easily relocated to change antenna direction.
• Flag, Pennant, Delta antennas operate with low signal levels. A 15-20 db gain preamplifier, made for low bands is necessary. The preamplifier is usually located physically in the radio room. The preamplifier in your transceiver is not adequate in gain, although it may help in conjunction with the external one.
• Use insulators where the transformer and termination resistor connect, to take mechanical strain away from components.
• For rotatable Flag, Pennant, Delta antennas. Use a light weight insulated support rod, such as fiberglass, from the antenna mast to the transformer for physical support of the transformer and coax cable.
• Reception direction. If you are standing by the termination resistor, reception is from the direction of the transformer.
• Any problem with poor reception, and/or poor front to back is most likely coupling to the transmit antenna. Transmit antenna detuning is often necessary. A relay may need to be installed at the transmit antenna feed point to disconnect the coax, or to disable/change other element tuning components while receiving.
• Increased common mode decoupling of the receiving coax cable is often done by adding turns to ferrite cores, beyond the matching transformer, where the coax first meets the ground. or a choke made from random winding many turns of coax in a 6 inch diameter coil, held together with plastic ties or taped.
• A deep null on the back of the antenna is useful for interference control.
• Typical terminations are non-inductive resistors, 903 ohms for point terminated Pennant antennas, 945 ohms for Flag antennas, and 948 ohms for Delta antennas.
• There have been problems using heat shrink on termination resistors, and multiple reports saying "no protective covering is necessary".
• There has been reports of twisted pair cable use as feed lines to Flag and other ground independent antennas. I decided to research some audio cables close to 50 ohms that have a shield, as I wanted to bury it. Located a cable with 55 ohm specs. The cable is designed for interior use but the outer covering looked strong enough for light outside duty. For a test I purchased enough for connection to my receiving delta antenna. After receiving the shipment, I put a 1 foot sample in the freezer to see if the insulation could withstand flexing in the frozen state. It was less flexible but the insulation did not crack or distort. Then, attached a variable carbon load resistor and re-checked it using a balanced to unbalanced transformer into my VSWR analyzer. Impedance was 55 ohms up to near 10 MHZ. Cable was not checked for loss, but connecting it to my Delta receiveing antenna, signal levels appear to be nearly the same as when connected to the coax cable. The antenna is working well and common mode pick up is now longer a problem. I will have another report after an extended test period. Wire info: I do not have any connection to this company. Shielded 55 ohm twisted pair cable.



The KB-5 Pennant, Flag, Delta, antenna transformer
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Bruce-K1FZ

Delta receiving antenna feed point

Delta receiving antenna termination