Post by billybobbybutton on Feb 18, 2015 11:42:55 GMT
Hi has any one got a SWR meter to tune the CB Antenna? If so maybe they could bring it to the next Pub Meet (marks cross) and I could have a tune up of me new rig? Or maybe I could come to you? I,m in the Brighton area? Thanks Bill
Post by billybobbybutton on Feb 18, 2015 20:31:33 GMT
Thanks, got the radio fitted today thanks to Tims direction but got a fault with it ( very low audio) so need to sort that out, we are planning to show up on the next marks cross meet, could you bring the SWR with you, ( want to get the antenna as sweet as possible)
Post by billybobbybutton on Feb 19, 2015 0:39:50 GMT
Hi Tim, re the audio so quiet you need to put your ear on the speaker to hear the slightest of sounds, I have looked at the trouble shooting area in the manual and it says it could be a power supply issue, I ran out of time today, but will run a wire direct from the battery and retest tomorrow.
Post by billybobbybutton on Feb 19, 2015 9:59:39 GMT
Update, Ran an a Power feed direct from the battery, made no difference, spoke to Thunderpole and the very kind Colin there talked me though some tests , it turns out there is a set fault, so just sorting out the replacement, ,
Post by Jeff - jthspace on Jun 5, 2019 14:44:54 GMT
Reminder - SWR - Standing Wave Ratio is the amount of signal being sent and then reflected back and NOT going out of the antenna - over 2.5 and it's not good! 2 or thereabout is satisfactory. Lower is good.
Go to the BOLD text if all you want is the summary
Following a conversation with Ian following his install of a new CB and the good SWR readings he got, it was mentioned that both he and I got a much lower SWR reading on a low UK channel than on channel 37. Although SWR readings are below 2 for us at channel 37 I mentioned that I would check what the readings are on my CB when using EUR or CE settings (remembering if you go across the pond, then you should use EUR or CE channels and NOT the UK ones which are illegal "sur le continent".
Anyway, I was disappointed to see that on channel 1 on EUR or CE, my SWR was in the red zone (over 3) and that's very bad. On channel 37 on EUR or CE, my SWR was just under 2 so that would be OK. I would expect that anyone else checking would find similar, but every set-up is different.
Therefore, without retrimming the antenna, I would be happy to use the upper channels (21 - 40) on EUR or CE setting without risk of damaging the CB but would not want to transmit on lower channels (01 - 20) without setting the antenna up properly for EUR / CE frequency ranges.
It is also important to note that WHERE you put the antenna on your car will affect the settings. The CB thinks that your antenna is twice as long as it is as it uses the car body as a ground plane so the car metal acts as a (kind of) mirror reflection of the antenna. If you have a CB Mini mag-mounted near the fuel filler / metal behind the soft-top then you will get a higher SWR reading than if you have one mag-mounted in the middle of the boot (which you cannot do - without some extra thought - on an ND as it is aluminium). Short antenna is convenient, long antenna is better.
CB frequencies (your transmission) are on the 11 meter band, so if your antenna is an equal divisible length of 11 meters, then the longer you can have the better (11 meters = full wave length / 5.5 meters = half wave length / 2.75 meters = quarter wave length (best compromise) / 1.375 meters = 8th wave length / 68cm = 16th wave length etc).
In summary - if you permanently change your CB to EUR or CE setting, then you will need to retrim your antenna.
If you are still awake . . . . .
Radio Four on LW on your radio set (wireless receiver!) is 198 meters - the radio wave being transmitted by the antenna is 198 meters long peak to peak - hence LONG WAVE and the wave can travel around the world bouncing off the ionosphere. If conditions are right, people in Australia could hear the Shipping Forecast.
Sky is being transmitted at about 8 times higher frequency than that of your microwave oven - but by the time the signal reaches you from 33,000 kms away, it is extremely weak so there is little chance of warming you up by mistake. Consumer ovens usually use 2.45 gigahertz (GHz)—a wavelength of 12.2 centimetres (4.80 in).
How to cook your ear . . . . and die an early death. Microwaves have doors for a reason! Notice her right arm has already fallen off.
Cooking a sandwich at Chicago World Fair 1933
Eunos 1993 in SU Classic Red. Imported 2016. 142,000 kms (Daisy) 2019 Mk4 ND2 Sport Nav+ GT in 45B Eternal Blue (Ginny)