Thread: HF antenna mounting

Originally Posted by POD

I've got onto a HF radio technician in Bunyip, taking the system to him tomorrow to get his opinion and assessment. Will see how we go.

Hi POD,
Have a talk to you tech about getting a 1/4 wave wire antenna cut for the two primary VKS channels, and how to hook them into the radio.

Channel 2 8.022 KHz should be 8.89 metre long
Channel 1 5.455 KHz should be 13.07 metres long (If my "enough to be dangerous" knowledge of radio is correct).

Antennas are a very vulnerable part of the system.
When we rolled our 110, the antenna, which was stored inside the vehicle, was broken in half, had it been on the front were it's normally mounted there would have been nothing left of it.
Had we not had a backup wire antenna, we would would not have had the radio for the very thing we carry it for. As it turned out we had mobile phone coverage, so didn't need the backup.
But I do get them out from time to time and use them.

Tony

Originally Posted by TonyC

Hi POD,
Have a talk to you tech about getting a 1/4 wave wire antenna cut for the two primary VKS channels, and how to hook them into the radio.

Channel 2 8.022 KHz should be 8.89 metre long
Channel 1 5.455 KHz should be 13.07 metres long (If my "enough to be dangerous" knowledge of radio is correct).

Antennas are a very vulnerable part of the system.
When we rolled our 110, the antenna, which was stored inside the vehicle, was broken in half, had it been on the front were it's normally mounted there would have been nothing left of it.
Had we not had a backup wire antenna, we would would not have had the radio for the very thing we carry it for. As it turned out we had mobile phone coverage, so didn't need the backup.
But I do get them out from time to time and use them.

Tony

Yeah this seems a good idea, a lot of radio websites offer emergency wire antennas but seem to want an excessive amount of money for what, if I understand correctly, is a length of wire with some coax and antenna connector soldered on one end. I guess Murphy demands that if you're going to have an accident in a remote area, the emergency comms gear is going to be the first thing to get busted. Stringing up a wire antenna has a certain MacGuyver-like appeal to it.

Originally Posted by POD

Yeah this seems a good idea, a lot of radio websites offer emergency wire antennas but seem to want an excessive amount of money for what, if I understand correctly, is a length of wire with some coax and antenna connector soldered on one end. I guess Murphy demands that if you're going to have an accident in a remote area, the emergency comms gear is going to be the first thing to get busted. Stringing up a wire antenna has a certain MacGuyver-like appeal to it.

Mine doesn't even have the coax.
Just a length of wire with a PL295 connector on one end and a loop soldered in the other.
I can get my radio in a position that the wire has a clear run out.

Tony.

Originally Posted by DeanoH

Another option might be to mount the auto tune base so it folds across the front of the 'box' behind the cabin (for more protection) and only affixing the whip when reqd, raise the antenna assembly when needed, removing the whip section when done.

If it's Selcall/Telcall you aspire to, a West Australian company, Jenal Communications, make a compatible (for your HF radio) microphone (Model SC2) that has a keyboard on the front, 1 - 0 * & #. This allows Selcall and Telcall facilities on HF radios that don't have this facility built in and is a good piece of kit.

I have an old RFK105 SSB HF radio that has one of these connected. The only reason I haven't tossed this antique set out is because of this after market microphone. It's free to good home if you want it. Your HF radio tech should have no problem fitting this to your 8525. BTW, this set does work and I have contacted VKS-737 Adelaide with it from my home, just down the road from you, but I definitely would not recommend it as a viable HF radio, but the microphone is very good.

Originally I was going to connect this microphone to a Codan X2, arguably the most robust Codan HF set built (but without Selcall/Telcall) but bought the 9323 instead.

Deano

I've got an X2 and eventually got a Jenal mic fitted. I suppose that all up it almost cost as much as a later radio with selcall but the cost was spread out over time and the X2, apart from having an excellent reputation, is easy to swap between vehicles. Anyway, the Jenal has made it into a great little radio as now I can call whoever whenever I like and I'd recommend it.

The length of a wire antenna or Dipole is calculated as follows,

300 ÷ freq (mHz) = Length (meters)

Very simple and can use any wire doesnt really matter although the thicker it is the greater the bandwidth of the antenna

On a trip out to Camerons Corner we hooked up a tuner to the dingo fence, tuned it up and chatted to a bloke in WA, I have used many things for an antenna, a fishing rod with wire wrapped around , I have even used a windmill tower and a earth stake, with a bit of knowledge in an emergency there are many things that can be used, when I go way all I take with my hf is a good manual tuner, a roll of wire and 20m of coax terminated at one end bared at the other, if my vehicle antenna fails I can be on the air in under 15 mins.



1993 Discovery 1 3.5l
2" Lift, Cranked HD Trailing Arms
31" Maxxis Mudders
Tons of Radios, Tons of Spotties

Originally Posted by Kevin B

The length of a wire antenna or Dipole is calculated as follows,

300 ÷ freq (mHz) = Length (meters)

Very simple and can use any wire doesnt really matter although the thicker it is the greater the bandwidth of the antenna

On a trip out to Camerons Corner we hooked up a tuner to the dingo fence, tuned it up and chatted to a bloke in WA, I have used many things for an antenna, a fishing rod with wire wrapped around , I have even used a windmill tower and a earth stake, with a bit of knowledge in an emergency there are many things that can be used, when I go way all I take with my hf is a good manual tuner, a roll of wire and 20m of coax terminated at one end bared at the other, if my vehicle antenna fails I can be on the air in under 15 mins.



1993 Discovery 1 3.5l
2" Lift, Cranked HD Trailing Arms
31" Maxxis Mudders
Tons of Radios, Tons of Spotties

But I think that without a bit of knowledge, i.e. me, you can blow something in your radio. True?

Originally Posted by Davo

But I think that without a bit of knowledge, i.e. me, you can blow something in your radio. True?

True yes, but its not as easy as you think to blow one up they will take a fair bit of punnishment unless you do something really stupid of course, its not difficult to do a bit of research and learn about the equipment your carrying, how best to use it and basic trouble shooting.

We still carry an 8528 Codan radio for last resort emergencies and have the auto tune aerial mounted on the bullbar LHS. This position appears the best in our case for a lot of reasons namely good radiation of the signal, visible, relatively safe from getting smashed off by trees and ease of installation.

From your pictures, position 1 you will reduce the effectiveness of the antenna by it being close to the vehicle and in position 2 you will remove fluro light tubes at half the servos. If the aerial is a visual obstruction, why not mount your base on the bullbar and wrap up the antenna and cable tie it to your roof rack, at the end of the day it is a last resort item, that is, unless you want to set up a daily sked.

As for dipoles and long lines, A dipole has to be tuned pretty well to the particular frequency for optimal transmission and reception, we use a SWR meter to initially trim ours but once set up they are excellent. If all else fails, in an emergency you can hook up a length of wire (say 10+ meters) and throw this up into a tree and connect the earth to a fence or an earth stake. The best long distance signal is usually from a lower wetter area with a good ground plane, not the top of a hill as you would think.

We are not part of the VKS group though. We have a few hundred channels programmed and there are always people chatting, especially on the likes of 6960 and 9164 (long range) and 2020 short range.



HF Radio Frequencies | Royal Flying Doctor Service



Our call sign is VJN49 if anyone hears us on our trips say g'day. We have had this Codan in 4 Land Rovers now for the past 18 years, still going strong.



Erich