CB aerials

[Jon_G4MDC]

Thanks for reminder about Dial-a-match, also info on rusty Stingers.

[G6Tanuki]

The *original* Stinger/Springer type antennas used copper-plated steel for both the spring and the whip; alas almost all the current ones use plain steel, painted - which as you've discovered tends to rust - and is not so effective electrically either (an antenna which is in itself made of significantly-resistive material like steel will dissipate a chunk of the RF energy as heat rather than radiating it: this is poor for efficiency but does at least make getting a low SWR easier - think of it as 'the antenna with a built-in dummy-load' !!).

Rather than "Springers", these days a lot of the local farm/4x4 types are using these:

https://www.sirioantenne.it/en/produ...w-delta-27m-95

which combine a springy base with a helically-loaded upper section, which radiates better than a simple whip.

[SiriusHardware]

Nice looking aerials - I wonder if Sirio are really still Sirio, or just a name bought by China now like so many other old brands?

With regard to paint, Stinger (Springer) aerials in particular are available in just about every colour of the rainbow - what are the thoughts on painted aerials? I can remember reading occasional articles on homebrew aerials, ones which used plastic pipe particularly as a way of weather proofing the innards, and the advice was often to use white pipe and avoid black because the black might contain undesirable materials such as carbon. Whatever the truth of that, it is noticeable that amateur base station aerials like the Diamond X-50 are invariably white rather than some other more discreet colour.

So, are there 'good' colours and 'bad' colours with which to paint an aerial? The world needs to know.

[crackle]

My friends dial-a-match melted the plastic base and the whip fell over.
I think he was using about 30 watts.

Mike

[G6Tanuki]

Sirio still seem to be good; I get their stuff from Knights CB: kcb.co.uk

As to paint-colours, I guess that when you're applying a *thin* layer directly to the active element it won't make much difference.

[that's not the case when you're talking about a wire-core embedded in a fibreglass outer-whip, when dielectric effects can measurably affect the velocity-factor].

In the past I've sprayed-over the white fibreglass outer tubes of Comet and Diamond 144/430MHz collinears with a mist of grey blue and green paint to make them less-noticeable; it's never measurably disturbed the antenna's operation.

[crackle]

Has anyone had experience with the ground plain kit for the Solacon Imax 2000.
Did you try it without first, what difference, if any, did it make.
"The ground-plane kit for the IMAX 2000 lowers the angle of the antenna's radiation plane, increasing its range. Kit includes four 6' radials and mounting hardware."

Thanks
Mike

[SiriusHardware]

The aerial itself looks like it is designed to be free standing / self contained, like a typical 1/2 wave or 5/8 wave vertical.

As such it should not 'need' a ground plane in the way that a quarter wave vertical or aerial intended to be mounted on a car body does need one. I suppose it's possible that adding one to this aerial lowers the radiation angle, as they seem to be implying.

[Steve G4WCS]

assuming its for home base use the T2LT is a good design

https://simonthewizard.com/2015/12/1...-make-swr-use/

or a vertical wire dipole.

[Oldmadham]

In Australia, the "base loaded" & centre loaded" whips were around for a while, but lost out to what the ARRL calls "normal mode helical antennas".
("normal" in this context doesn't mean "usual", but "at 90 degrees to" as in geometry).

All they are is a fibreglass whip, with a helical winding from bottom to top, with the same pitch all the way.
Sometimes they have a stainless steel "sting" at the top for adjustment, but others have no sting, & need to be cut to resonance .

I think " the boys in blue" looked askance at any really unwieldy apparatus hanging off a car.
The early pre-legalisation CBers had enough to worry about with Radio Inspectors, without also incurring the Wrath of the local constabulary!

[SiriusHardware]

Looking at Australian TV dramas, especially those set outside cities, I often see what are obviously large HF aerials on vehicles - often bumper mounted due to their size - including police vehicles. They don't look like CB aerials, their length and the size of the loading coils suggest a much lower frequency. What might they be for, some kind of HF based mobile telephone system?

As a UK radio enthusiast I always envied Australia's UHF CB radio system - for a number of years we also had a CB system on very high UHF (934MHz) but it was such a leading edge frequency at the time that equipment was expensive and take-up consequently poor and the band was eventually taken over for mobile use. Ironically, the RF components which were produced on a huge scale for 900MHz mobile phones would now make 934MHz CB very affordable.

In the run up to the legalisation of CB on 27MHz in 1981, there was a serious movement to try to get the UK system established on high VHF, around 200+ MHz - it would have been ideal, short, efficient aerials, with no day to day interference rolling in and making local communication difficult or impossible as is sometimes the case on 27MHz in the summer months.

[electronicskip]

The 934Mhz UHF Rig was always the one which eluded me .
The price was very prohibitive and the popularity of 27 had always been established so it never really took off.

Still looking for one for my collection if anyone has one kicking around at a reasonable price.

[SiriusHardware]

I remember forum member 'Biggles' had a couple of 934 sets pass through his hands several years ago, I don't know what happened to them.

It goes without saying that with the band having been withdrawn many years ago, it wouldn't be possible or legal to use them in the proper sense. Maybe if you fitted them both with dummy loads you'd be able to use them as shed-to-house wireless intercoms.

I certainly agree they would be interesting to have in a collection, I don't have any in mine either. For me, it would have to be the Cybernet model, I think. If the rigs themselves are rare, imagine how hard it must be to find an original commercially made 934MHz aerial - there may have been some interesting ones, as beams, i.e, Yagis, were actually allowed on that band.

[G6Tanuki]

Originally Posted by SiriusHardware

Looking at Australian TV dramas, especially those set outside cities, I often see what are obviously large HF aerials on vehicles - often bumper mounted due to their size - including police vehicles. They don't look like CB aerials, their length and the size of the loading coils suggest a much lower frequency. What might they be for, some kind of HF based mobile telephone system?

Yes, outside urban areas, the Aussies have an extensive HF-radio network for interworking between cattle/sheep-stations, mines, logging-camps and the like. Usually in the low end of the HF range, it also encompassed the "Flying Doctor" frequencies - see http://www.swld.com.au/pages/aus_rfds.htm

You can still get an "Outpost" HF radio licenced - https://www.acma.gov.au/licences/outpost-radio-licence

Canada had a similar system: I remember in the 80s importing HF radios/antennas from their "Spilsbury Corporation" for a particular project. I've still got a Spilsbury STA-270 remote-tuned HF mobile antenna here, which would work nicely on 5MHz if we were allowed to operate mobile on that band.

[SiriusHardware]

Interesting, thanks. I went to have a look at the links to try to get an idea of mode and frequency but all the documents are couched in such worthy language that I kept falling asleep. I gather it must be SSB, and down in single figures MHz which is what I would have expected from the appearance of the aerials.

[Oldmadham]

Originally Posted by SiriusHardware

Interesting, thanks. I went to have a look at the links to try to get an idea of mode and frequency but all the documents are couched in such worthy language that I kept falling asleep. I gather it must be SSB, and down in single figures MHz which is what I would have expected from the appearance of the aerials.

Yeah, it is SSB & like almost all non Amateur stuff, USB.
They are fixed channels, & from memory low HF, though I recall hearing some similar stations around 13.9MHz.

The Oz UHF CB channels are around 477MHz.
There are repeaters on this band, which makes it quite useful.
The 27MHz diehards badmouthed it a lot to start with, but the "truckies" took to it, & it became quite successful, certainly enough for manufacturers to produce special ranges of radios especially for that service.

Back when we still made stuff in this country, Philips made a UHF CB, & as a bonus, also produced a very similar 70cm Amateur transceiver.

Like 27MHz, though, it has lost out to cellphones.

[SiriusHardware]

What is the output power on the UHF CB service, and what sort of aerials are permitted? Can you use beam / directional aerials on that band? I assume the mode is FM.

I'm surprised it is popular with mobile users, from experience with 70cms mobile UHF is much more prone to mobile 'flutter' than, say low VHF which is a popular taxi simplex band.

I guess it must have been the availability of repeaters which swung it for mobile users of the UHF CB service.

That said, I think I have often seen lorry drivers in this country talking to each other on what look like PMR446 (UHF / Half watt) walkie talkies when travelling in a close convoy - I'm sure it covers that scenario perfectly. CB aerials on lorries are sadly a much less common sight than they used to be in the UK.

[electronicskip]

Originally Posted by SiriusHardware

What is the output power on the UHF CB service, and what sort of aerials are permitted? Can you use beam / directional aerials on that band? I assume the mode is FM.

I'm surprised it is popular with mobile users, from experience with 70cms mobile UHF is much more prone to mobile 'flutter' than, say low VHF which is a popular taxi simplex band.

I guess it must have been the availability of repeaters which swung it for mobile users of the UHF CB service.

That said, I think I have often seen lorry drivers in this country talking to each other on what look like PMR446 (UHF / Half watt) walkie talkies when travelling in a close convoy - I'm sure it covers that scenario perfectly. CB aerials on lorries are sadly a much less common sight than they used to be in the UK.

Midland actually make/made a PMR446 UHF Half watt full size rig for use in lorries and cars for the public but i was never that popular.

[SiriusHardware]

There were a few oddballs like that, the main problem being that the aerial had to be 'integral' to meet the PMR446 spec, so either they used a magmount on which the cable was hardwired both at the aerial and the radio end, or more unusually, the RF electronics were in the base of the magnetic aerial and the speaker / microphone cable and DC power cable ran across the roof and down through the door seals and into the car.

If I could find a couple of the first type ('Mobile radio' form factor with hardwired magmount antenna) I would actually have a use for those. They were quite expensive though, typically around £80-£100 I seem to remember.

Anyone wanting a PMR446 vehicle radio now would probably just buy a freely programmable Chinese UHF mobile for about half that price and program it to 'Be' a PMR446 mobile, although of course it would not be type approved or legal to use for that purpose.

[electronicskip]

Just seen it still being sold new on Amazon as a complete kit including micro magmount antenna for £149 .

https://www.amazon.co.uk/Midland-GB1.../dp/B019QO2E4A

(no connection with business)

That's rather cute but a bit pricey.