Topband: 160M EWE Problems

[JC]

Hi folks

I would like to add some comments to receiving antennas issue. Any resonant thing (wire, cable, rotor cable tower, TX antenna...) will interact with the RX antenna if they are in the same polarity, different polarity has 27 dB or more of isolation due the polarization itself.

The inverted L is easy to detune, just open the wire from the coaxial and check the noise on the EWE. The noise on the RX antenna needs to decrease one or 2 S units. However, it is possible you will not see any difference. The reason is that you may have another point where common noise is deteriorating the directivity of the RX antenna. If it work, just add a relay for detuning the Inv L during RX.

The integration with the inverted " L " TX antenna is the easy one do fix the others resonant "things" could be difficult to recognize. Example, if you have a low dipole or elevated radials, these "things" will destroy any directivity of nearby RX antennas, and nearby distance on 160m means 300ft or more, one wavelength. Rotor cable, VHF or other's 120ft feed lines could be resonant and a good reflector for noise and re-radiate them too.

Lack of good ground (or no ground at all) is receipt for failure on RX. Running the cables outside the tower and far from the ground is the preferred way to screw things up.

I am following every installation of my WF's and there is an issue very frequently found. It is bad connectors contact with the cable shield. Cold solder, no solder, little copper wire on the braid. One single point with a bad shield can ruin you RX system.

Doug Waller when he build the first WF was very disappointed with the results until he found a RCA connector with one RCA   ear not contacting the preamp input RCA female. Just one little gap in ear with no contact was enough to leak noise into the preamplifier input. After fixing the bad contact, the RX antenna started to work with good directivity. PL259 or a F connector with bad contact with the braid can cause several S units of noise.

Spending big money on the radio and do not care about the quality of the connectors used for RX is no sense.

Open frame relays (not coaxial relay), open contact switches, plastic boxes are the most common points to add noise and destroy the directivity pattern.

Running cable outside de tower and ground them at the base is not a very popular solution. It is hard to run the cables inside the tower they say. As a result RF is everywhere in the shack. No solution for that too.

I am just trying to help, there is no free beef regarding good RX systems.

73's
JC
N4IS