Footloose replied:

Tim, earthing is something you can't have too much of with an a/t. However, I don't think that's your problem.
Your aerial seems to tune ? Then earthing isn't going to make a huge difference with receiving.
Are you sure that the radio is working well ? Have you tried disconnecting your aerial on a broadcast station frequency and connecting a long bit of wire to prove the receiver and aerial is working ?
Are there any lights on your radio, or a beep system that tell you when you're aerial is tuned ?
Do you have a friend with a similar system that you can try your radio in his truck ?
If all else fails, grab someone who is familiar and qualified with your setup and ask them to have a look at it.
By the way, where are you located ?

Mike Harding replied:

Hi Tim

I suspect location is a lot to do with it. I live on the Mornington Peninsula (about 80km LOS from you) and despite having a decent wire dipole, antenna tuner and quality radio gear rarely get good reception on VKS737. I guess their antennas are intended to put maximum into the central areas of Oz. Try tuning in to Amateur transmissions or the BBC World Service for a different perspective.

Earthing: flat copper strap or braided strap as short as possible and as thick as possible to the chassis and body. RF and earth - the rule is you can't have too much of it.

Mike Harding

Member - Phil G (SA) replied:

Earth to both with a thick cable of strap - theres a heap of metal in the body which is what its about. Best place for the body earth is usually one of the fat bolts on the body side of the tailgate hinges - scrape paint, smear vaseline, and use a new bolt. The earth makes a big difference to the quality of your transmissions.

Tony MD replied:

Hi Tim.
1. The radio signals from the VKS bases are not strong here in Melbourne where there is also high background noise levels.
2. An HF mobile whip is a relatively inefficient antenna due to its small length (measured in wave lengths - 300 / frequency in mHz).
3. Increasing the length of the antenna - by simply connecting a wire to the whip that is about 8 metres long - will improve the efficiency. The auto-tune antenna should tune this as a 1/4 wave antenna. (For 8022 kHz)
4. As others have stated, bond the antenna RF earth to body and chassis with as short a strap as possible.
5. You need to listen and call at the right time of day. On Wednesday, Alice Springs was reasonable between 1:30pm & 2:00pm. More activity can be heard in the evenings. 8022kHz is heard to have the most traffic here.
6. As Mike suggested, try listening to other frequencies. The Amateur 40 metre band - 7.000 to 7.100 carries a fair amount of traffic in the afternoons, particularly weekends. later at night, try the 80 metre band 3.550 to 3.700mHz. Note that both these amateur bands use Lower Sideband where VKS and nearly all other services use Upper Sideband. You should find some activity on 20 metres 14.100 - 14.300 mHz Upper Sideband during the day.
7. If you want to try a test, contact me.
Cheers, Tony.

Tim Owen replied:

Thanks All.

The radio is working (ie. I have now heard VKS skeds out in charters towers and alice springs and perth - scratchy and only sometimes, and I have been able to transmit to these bases at the times when I can hear them). Thanks to one of the VKS operators (Rox) I have also talked through the St Marys base which gave me a good idea of what a clear transmission is like. I'm realy just trying to make sure that I have done everything I can to get the best out of the radio before heading off.

I'll take the advice and add an earth strap to the body and leave the existing earth to the chassis.

Mike - thanks for the report on reception to VKS from Mornington Peninsula. It's good to know that my experience is not too different to others nearby.

Thanks for all your help.

anglepole replied:

Hi Tim,

Earthing to the back door can be a bit sussy. The back door is usually earthed via its hinges and or lighting wiring. Earth the antenna to the chassis side of the hinge or place a strap across the hinge to earth the back door.

Here is a prediction for vks Melbourne to Alice using a 1.65 metre whip

Hope this helps

===============================================================================
ASAPS V5 FREQUENCY PLAN PREDICTIONS ---------------------------- 2 Jun 2007
===============================================================================
Circuit 1: Melbourne-Alice Spri Distance: 1892km Date: June 2007
Tx: Melbourne -37.82 144.97 Bearings: 323 149 T-index: 9
Rx: Alice Springs -23.70 133.86 Path: Short Path
Selected frequency set: VKS-737 Network
3.995 5.455 8.022 11.612 14.977
===============================================================================
Mode: 1F TakeOff Angle: 8-11 | Mode: 1E TakeOff Angle:1
Probability > 90% | Probability 50-90% |
===============================================================================
Time Frequency | Time Frequency | Time Frequency
UT MHz | UT MHz | UT MHz
0000-0800 11.612 | 0000-0800 14.977 | 0000-0200 11.612
0800-0900 8.022 | 0800-0900 11.612 | 0200-0400 14.977
0900-2200 5.455 | 0900-2200 8.022 | 0400-0700 11.612
2200-2300 8.022 | 2200-2300 11.612 | 0700-0800 8.022
2300-2400 11.612 | 2300-2400 14.977 | 0800-2200 None
| | 2200-2300 5.455
| | 2300-2400 8.022
===============================================================================
Mode: 2F TakeOff Angle:23-27 | Mode: 2E TakeOff Angle:8
Probability > 90% | Probability 50-90% |
===============================================================================
Time Frequency | Time Frequency | Time Frequency
UT MHz | UT MHz | UT MHz
0000-0800 8.022 | 0000-0800 None | 0000-0700 8.022
0800-0900 5.455 | 0800-0900 8.022 | 0700-0800 5.455
0900-2200 3.995 | 0900-2200 5.455 | 0800-2200 None
2200-2300 5.455 | 2200-2300 8.022 | 2200-2300 3.995
2300-2400 8.022 | 2300-2400 None | 2300-2400 8.022
===============================================================================
Chris

obee replied:

like the man said, time of day can have a lot to do with hf getting thru. Hf bounces off the ionosphere and skips over parts of the earth. The ionosphere reacts to radiation from the sun especially during the high sunspot activity parts of the sun cycle.

Owen

one time vk6us but no more.

DarrynJ replied:

Hi Tim, I see you are starting too have some luck with your HF. One thing I just thought of is too check the Negative battery terminal and the cable especially the small cable that goes to the body from the terminal as you are currently using the body for most of your earthing.
Regd's Darryn