CB hints and tips......

[Yorkshire Andy]

Any tips on swr reduction?

I've moved the antenna up and down and still no change

Using a thunder ant and mag mount

Got CH 40 to about 1.8 but

Ch1 is just scraping 2.5

?

Cheers in advance

[HBP]

I have never had a lot of luck with mag mounts and always ended up with a mount that's got some electrical connection to the vehicle.

A few ideas:
Move the mag mount
Make a choke in the coax close to the antenna by coiling it up. http://www.k3dav.com/rfchokecoil.htm
Trim the coax a bit and fit a new plug
Try a hatch or mirror mount depending on the vehicle you have.

[Hamradioop]

With over a Megaherz of frequency span I would do one of two things tune for low SWR on the centre of the span or tune to my favourite channel. Mag mounts can be a real challenge to cut for frequency. a boot lip or hatch mount may be a better option and will not damage the car as much. and will give a better earth.

Got CH 40 to about 1.8 but

Ch1 is just scraping 2.5

this indicates your radiating element is on the short side. the other way round indicates it is on the long side. You could also insert an amu in line between the radio and the antenna but it will introduce losses.
AMU= Aerial Matching unit also known as a transmatch, match box etc.

TM-999 swr/power meter & Matcher

A very popular antenna tuner for CB for up to 100W.

The meter will give direct reading of either swr or power, the power scale being selectable from either 10W or 100W.

The matcher can be switched on or off.

Frequency: 26-28MHz
Max Power: 100W

[Yorkshire Andy]

Thanks turns out i made a school boy error and errm got a bit carried away with my mates cordless grinder and cut it off when I needed to raise it

Need a new whip antenna and will try again..
Local shops been good and lent me a rigid base loaded antenna just to make sure its not the mag mount and its spot on getting about 1 on both ch1 and ch40

Got a nice big loom pulled to the battery yesterday with waterproof fuse holder close to the battery just need to mount the unit now

[Yorkshire Andy]

just been playing managed to pick up a conversation oneside of which was a minimum of 16 miles away

[Wulfshead]

Andy,
I may get told different but I also made the same mistake with my 1/4 wave ground plane antenna.
What I did was use an electric cable connector and screwed some antenna rod into the top. I was then able to re-cut to gain a better SWR match.
I did cut about 40mm of the element that was to short so I had enough new rod to play with, got a good SWR also.

Wulfshead

[Hamradioop]

Same rule with Aerials as wood measure twice cut once.

[Yorkshire Andy]

Ive got it something like now with it about 2.0 on ch1 and 1.5 on ch40..... with a whip but cant get any better

http://www.thunderpole.co.uk/large-cb-a ... bitor.html



yet with this one:

http://www.thunderpole.co.uk/large-cb-a ... yager.html


gives sub 1 readings on both channels (using the same mag mount )

[HBP]

You have 2 very different loading coils on those antennas. The one that gives a better swr may well be better designed and as it can't move it will be more electrically stable.

Basically, one is probably a better antenna than the other.

A quarter wave whip for cb (11m band) would be approx 2.75m long. Adding a loading coil makes it appear electrically longer than it is so is always a compromise.

[dangerman]

What kind of range is a set up like this capable of? How many people are likely available to communicate with?

I worry about CB because I hardly know anyone who uses it. And I know they're only short range.