HF static follow up

Great news Wayne that you have solved the static problem ie Sydney, must be making the point it is time to leave and get away from that static for a while. All the base operators on VKS737 will be happy for you to call in each day. I usually do Cheers Ray V2010

Hello Wayne,
So spill the beans, what where "a lot of factors" besides Sydney itself that caused the static?
Might help all of us one day,

Geoff.

Just a few radio & antenna basics that may help in understanding why things are as they are with HF radio.

There is heaps of RF (radio frequency) interference generated in cities & towns.
Firstly there are overhead power lines which can also re-radiate other stray signals. Then there is the leaky overhead cable TV / Internet systems - sounds like a chopping noise. Also interference from home & comercial electronic equipment, traffic lights & alarm systems. Every time I go past a particular location whilst transmitting on HF I trip both a car & a shop alarm system :-).
Video cassette recorders are another bad interference generator.
This is why we don't want any further sources of interference such as BPL etc.

Any HF VKS737 mobile antenna will be shorter than the optimum length (being a 1/4 wavelength minimum - use the formular 300 divided by the frequency in MHz for a free space measurement then multiply the result by about 95% for a real practical antenna)
Our short antennas - particulary on the lower frequencies, will radiate inefficiently - will heat up the ground with only a portion of the transmitter power going through the antenna. The best way to reduce these losses is to have a really good antenna earthing system. Counterpoise wires or radials (1/4 wave) will greatly increase the radiation resistance & efficiency of the antenna. The short antenna will also have a high angle of radiation which means good short distance contacts in particular on channels 1 & 5.
Base loading is the common method for 'loading' mobile HF antennas. The unfortunate result of this is that the loading coil will be at a high antenna current point. Better antenna efficiency can be obtained when the high antenna currents are distributed further up the antenna.

HF propagation, with the exception of ground waves, requires the RF signal to be reflected off the F layer of the Ionosphere. During the day at frequencies below 10MHz, the F layer is obstructed by the D layer. The D layer is generated by solar radiation & breaks down at night. This is why Channels 1 & 5 are best at night & channel 2 during the night as well as early mornings & evenings.
Channels 3 and 4 are best for longer distance communications. Propagation will be influenced some waht by the solar cycle. Channel 4 should provide reasonable daytime coverage from Melbourne to Perth of Brisbane. Channel 3 may be best for slightly shorter daytime contacts. Use the Beacon call facility to gauge the best frequency / time for your location.

Ground waves are best for Channel 5 during the day & may provide a reliable coverage of up to 200KMs.
They are caused by the radio wave being bent and tilted foward by the curvature of the earth. Ground losses will determine the reliable distance of a ground wave contact.

As a summary, to improve your signal, try a longer antenna and some ground radials. Remember that the conditions of the VKS737 service & outpost station licence (RFDS) is that land mobiles are just that - not to be connected to permanent or fixed station antennas. Also remember that your improved radio signal may cause interference to other users so listen first for a quiet channel.
An improvement in antenna efficeincy will affect both transmissions & reception.

Hope that this is of some benifit.

Tony, VK3CAT, Victor 5715, VZU494
Also WIA radio examiner.

Wayne & others, I also find that with static just reduce the volume then you can here through the noise if that makes sense. Glad to be of help.