Poll: If Chosen as our preferred frequency, would you support CB 27/81?

[Lightspeed]

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(1 July 2012, 20:11)Barneyboy Wrote: would love to get right one had a midlands cb but could only hear not talk so my money is hear just need a push have a 18 foot on top of 25 foot scaf pole up just need right rig to get and swr meter or some thing about ground plan please help me im comfused

Hi Barneyboy,

A picture paints a thousand words. Attached is a pic of what you need to do.

You should really have a minimum of three groundplane wires and these should be spaced evenly around the antenna.

SWR is adjustable by changing the angle of the ground planes relative to the antenna ( that is to say moving the point at which you peg in the guy wires nearer or further from the base of the antennas.

Does this help?

[James Jackson]

what would i need as i cannot put up an aerial, and how much would it cost?

[Lightspeed]

(1 July 2012, 20:49)James Jackson Wrote: what would i need as i cannot put up an aerial, and how much would it cost?

JJ when you say you cannot put up an antenna, can you tell me how you are situated and what is stopping you putting up an antenna. I'll draw our some plans for stealth antennas a little bit later on, Very effective antennas can be made for less than ten quid.

If you can answer my questions I'll give you some ideas ( I hope!)

[The Local Ned]

SWRing in for base antennas is slightly different from mobile ones...dunno where LS is getting that idea from , most antennas can be SWRd in by adjusting a grub screw that alters the physical length of the antenna , which will change the SWR between it and the radio , a SWR of 1:1 is the best possible result , but in my experience it is achieved very rarely.

Groundplanes CAN alter the SWR , but are generally used to 'strengthen' the signals range , an antenna doesnt radiate signals uniformally i.e in a circle , certain directions will have a better range , groundplanes can be altered to try and strengthen the signal in those other directions.

[Lightspeed]

(1 July 2012, 21:43)The Local Ned Wrote: SWRing in for base antennas is slightly different from mobile ones...dunno where LS is getting that idea from , most antennas can be SWRd in by adjusting a grub screw that alters the physical length of the antenna , which will change the SWR between it and the radio , a SWR of 1:1 is the best possible result , but in my experience it is achieved very rarely.

Groundplanes CAN alter the SWR , but are generally used to 'strengthen' the signals range , an antenna doesnt radiate signals uniformally i.e in a circle , certain directions will have a better range , groundplanes can be altered to try and strengthen the signal in those other directions.

TLN,
Thanks, you are right about adjusting the length of the driven element.

Barneyboy is struggling to get his antenna to work at all, and I'm geussing that raising and lowering the brute is to adjust it for SWR is going to be a fairly big task. Adjusting ground planes ( which it appears he does not currently have) is possibly an easier solution

Ideally you should adjust driver first and then ground planes.... and adjusting the ground planes by raising or dropping them does indeed have a fairly big effect on SWR... That's just my experience, others may know of beter or more simple solutions.

You seem better clued up on CB than me. Do you know the antenna BB is using? I've assumed that its a quarterwave of some sort. Its not a halfwave is it? If halfwave groundplanes will not be needed at all.

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(1 July 2012, 20:11)Barneyboy Wrote: would love to get right one had a midlands cb but could only hear not talk so my money is hear just need a push have a 18 foot on top of 25 foot scaf pole up just need right rig to get and swr meter or some thing about ground plan please help me im comfused

Hi Barneyboy,

While writing my last reply I realised that you have said that your antenna is 18ft long, I reckon that make it a half wave ( 5.5 meters) Very often this sort of antenna does not have groundplanes at all.

Have a look at the manufacturer's mounting instructions and adjust accordingly.

Certainly don't go adding ground planes to it until you are sure it needs them.

[The Local Ned]

(1 July 2012, 20:01)Lightspeed Wrote:

(1 July 2012, 19:38)The Local Ned Wrote: I already have an old walkie-talkie lying around somewhere , and from previous experience using it , unless we have a prepper within 2 miles of me I won't be able to contact any of you.

Even with a base station using a half wave antenna ( silver rod - 18ft ) and rg8 coax my best range was something like 5 miles on a good day.
Even when using a burner.

Just 5 miles with a big antenna like that seems very low. Do you live at the bottom of a COAL mine??

I get better range than that with a 1/2 watt handheld on 70cms.

Fixed that for you.

As I stated before - location will alter the signal.
I live in the 'Kelvin Valley' area , with the Campsie Hills to one side and a high wooded area directly behind me.

On a good day i.e sunny , I could contact areas close to Glasgows city centre , and to the North - just short of Falkirk.
That was using a 25w burner , a president rig and a silver rod up on a 3m pole on the roof of my dads house.
Using the legal UK stuff on 4W I got nowhere near that.

The president rig had been tweaked to kick out over 8W.
The SWR was just below 1.5:1

Basic antennas such as dipoles are very effective and easy to setup , those other antennas with groundplanes do work better but are more complicated to setup correctly mate.

[James Jackson]

since having a spinal operation i have had to move back in with family, their is lots i can get away with but they will not let me put anything like that up or mess with any structure of the house

[Nemesis]

People interested need to add their Location, according to the main site post.

[Lightspeed]

(1 July 2012, 22:21)James Jackson Wrote: since having a spinal operation i have had to move back in with family, their is lots i can get away with but they will not let me put anything like that up or mess with any structure of the house

Hi JJ

Sorry to hear about hour difficulties. I hope you are on the mend now?

Its understandable that your family do not want you to disfigure theit home :-)

An end fed halfwave wire may be a viable option. This is a 5.5m long THIN wire. I have one at my mother's house. She had the same reservations but now has completely forgotten that there's an antenna theer. neither she nor her neighbours can see it so no issues at all .

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(1 July 2012, 22:11)The Local Ned Wrote:

(1 July 2012, 20:01)Lightspeed Wrote:

(1 July 2012, 19:38)The Local Ned Wrote: I already have an old walkie-talkie lying around somewhere , and from previous experience using it , unless we have a prepper within 2 miles of me I won't be able to contact any of you.

Even with a base station using a half wave antenna ( silver rod - 18ft ) and rg8 coax my best range was something like 5 miles on a good day.
Even when using a burner.

Just 5 miles with a big antenna like that seems very low. Do you live at the bottom of a COAL mine??

I get better range than that with a 1/2 watt handheld on 70cms.

Fixed that for you.

As I stated before - location will alter the signal.
I live in the 'Kelvin Valley' area , with the Campsie Hills to one side and a high wooded area directly behind me.

On a good day i.e sunny , I could contact areas close to Glasgows city centre , and to the North - just short of Falkirk.
That was using a 25w burner , a president rig and a silver rod up on a 3m pole on the roof of my dads house.
Using the legal UK stuff on 4W I got nowhere near that.

The president rig had been tweaked to kick out over 8W.
The SWR was just below 1.5:1

Basic antennas such as dipoles are very effective and easy to setup , those other antennas with groundplanes do work better but are more complicated to setup correctly mate.

Not the best of locations for a station, you were doing well to get out that far.

[Martin200261]

I reckon CB27/81 is the best option for us to standardise on.

For those who can / want to buy new kit most new rigs have both 27/81 and CEPT giving 80 channels.

For those tightwads like me there is a lot of 2nd hand equipment available for very low prices on ebay.

It's difficult to decide what is the best way forward as we don't really know the situation we may find ourselves in, people may be concerned about opsec but no matter what radio you use there are plenty of scanners around that can listen in on virtually any frequency you'd care to choose. My reasons for liking 27/81 is the sheer number of rigs lying around gathering dust in cupboards, in a shtf scenario we are likely to want to communicate with as many people as possible even if only as a way of challenging strangers from a safe distance.

I think we need to consider PMR446 as a companion option since the units are so small and ideal for short range comms where we don't want to be transmitting too far away.