Some more ignorant HF questions.

Submitted: Friday, Jun 13, 2008 at 09:30
ThreadID: 58710 Views:2808 Replies:8 FollowUps:3
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Sorry to be annoying, but I DO value practical experience very much. Particulary considering that I am intent to use HF equipment EXACTELY in the way as majority of you do.

Last mystery been solved – apparently I have faulty self-tuned antenna with inappropriate whip. They gave me replacement antenna while sending mine back to Barret (third time!) and it works in much more sensible way from my POV. However I been trying to listen to sked from Adelaide base station last evening (I am in metropolitan Melbourne) with very little success. Very faded, only possible to understand some words. Meantime I was be able to beacon Perth and Darwin station successfully. I do understand that this HF propagation is rather witching then since and there is possibility to clearly hear station thousands miles away and not be able to hear someone around corner.

So PRACTICAL questions.

1. Is it being in metro area make thing much worse? I am talking about “radio pollution” in urban area – is it make huge difference?

2.Is anyone can listen to Adelaide skeds regularly from metro Melbourne?

3.What is the best way to ground antenna? Anyone been fiddling around with grounding and can give practical advise? (Barret 950 with 510 self-tuned antenna mounted on spare wheel carrier arm on LC80)

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Reply By: Member - Davoe (Yalgoo) - Friday, Jun 13, 2008 at 09:45

Friday, Jun 13, 2008 at 09:45
1. hell yea city is interferance all the way
2. from WA can often pick up adelaide better than perth, but even though i get them 5x5 they usually barely get me. From Adelaides comments it seems they uffer alot of interferance I dont get from WA
3. I would go with an earth braid straight to the chasis
AnswerID: 309654

Follow Up By: Member - Serg (VIC) - Friday, Jun 13, 2008 at 10:24

Friday, Jun 13, 2008 at 10:24
Thanks for replay
FollowupID: 575613

Reply By: Member -Signman - Friday, Jun 13, 2008 at 09:59

Friday, Jun 13, 2008 at 09:59
Hi Serg
Just sent MM to you...

AnswerID: 309657

Reply By: Member - John (Vic) - Friday, Jun 13, 2008 at 10:02

Friday, Jun 13, 2008 at 10:02
Are you suggesting that you currently "Don't" have the autotune earthed at the moment??
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AnswerID: 309658

Follow Up By: Member - Serg (VIC) - Friday, Jun 13, 2008 at 10:24

Friday, Jun 13, 2008 at 10:24
John, of course it is earthed to body. But I have read that earthing in the car not that straight and obvious – this is where question came from.

FollowupID: 575612

Reply By: ddr - Friday, Jun 13, 2008 at 11:06

Friday, Jun 13, 2008 at 11:06
Last time I tested the Radio post change in the install I could get Adel from Metro Melb with a 4 out of 5 receive according to the Op.

I don't do it regularly however.
AnswerID: 309668

Reply By: Member - Lewis K (QLD) - Friday, Jun 13, 2008 at 12:32

Friday, Jun 13, 2008 at 12:32

Just sent you a members message.
AnswerID: 309681

Reply By: traveller2 - Friday, Jun 13, 2008 at 15:01

Friday, Jun 13, 2008 at 15:01
Serg as has been said the city and suburbs play havoc with reception. Try and find a reserve/park in a gully which should give you better (quieter) reception.
Try listening to the base stations to the north rather than east west as the signal travels better nth/sth than east/west.
AnswerID: 309694

Reply By: MEMBER - Darian (SA) - Friday, Jun 13, 2008 at 15:48

Friday, Jun 13, 2008 at 15:48
Presume you have the 910 auto tuning antenna (blue outer case) on you 950. I have the same setup - apart from two minor technical repairs over the last 7 years (one fixed under warranty and the other costing $88) I find it an excellent, reliable unit. Barrett have always provided first rate service to me (IHNA. Presuming your installation is all up to spec............a note or two from my experiences while operating Adelaide Base for VKS737.
1. HF conditions are always variable, mainly depending on solar and weather variations.
2. IME, mobiles in Melbourne are usually only 'average' coming into Adelaide at the best of times.
3. At present, conditions are tending quite long - Adelaide Base is regularly 'comming' with the Kimberley and the Pilbara in WA at present (Cape York too). You are probably a bit close in Melbourne for 8022khz - 5455khz might be better.
4. If you gear is setup properly, you should happily reach the distant bases at present.
PS: Didn't notice if you are a member - we can only comm with members of course, except in the case of emergencies.

AnswerID: 309699

Follow Up By: Member - Serg (VIC) - Friday, Jun 13, 2008 at 16:07

Friday, Jun 13, 2008 at 16:07
Thanks for info. Yes, I am a member of VKS737 - V1095.

FollowupID: 575653

Reply By: Tony MD - Friday, Jun 13, 2008 at 16:22

Friday, Jun 13, 2008 at 16:22
Hi Serg.
I am in suburban Melbourne & it takes a strong signal to get over the noise level. Recently, what may have been a radio telytype (RTTY) transmission was causing havoc. This is using a full wave open wire loop antenna for receive.

Recently, Alice Springs has been a more reliable signal than Adelaide on 8022kHz. Propagation is affected by time of day and the frequency in use. Improving the antenna efficiency by extending the auto tune whip top to close to a 1/4 wave length by using a bit of wire (No longer than 9 metres for 8022kHz) will also help.

I was able to clearly hear Richard Kovac a few days out of Coober Pedy on 802kHz.

RF earth and DC earth are completely different things.
With RF, the electrical current is subject to the "Skin Effect". That is that it flows on the surface of a conductor rather than through its total cross sectional area. The skin effect becomes more pronounced as the frequency increases. This is why a flat braid / strap is best for earthing your antenna.

At UHF & higher frequencies, a hollow tube type of coaxial cable (hard line) for low loss is used (Andrews Communications - LDF450, 550 etc)

In a similar installation on my Landcruiser with a Codan 9350 antenna & 8528 radio. I have the antenna mounted to a welded bracket on the rear wheel carrier. The antenna is bolted to this bracket & also uses an earth strap onto the swinging wheel carrier, which in turn is bonded to the chassis which is bonded to the body.

The radio chassis is bonded to the body at a seat mounting bolt with a similar strap.
Ferrite beads & soft iron torroidal cores are used as RF chokes at the radio end of all cables - being antenna coaxial cable, antenna control cable, remote head cable, microphone cable, power cable. This is predominantly for the purpose of choking off any RF currents that these cables may be inadvertently picking up (by acting as an antenna) which can cause distortion in the transmitted signal (generally called RF feed back)

The radio is wired direct to the auxillary battery via a circuit breaker using 10mm squared (cross sectional area) cable.

Hope this is of some help.

Cheers, Tony
AnswerID: 309703

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