Question about Radio Shack TRC-503 CB Radio

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Static I have recently set up a home base Sirio Antenna, but all I can hear is static noise on the rig. SWR and coax both fine. The rig works fine in my car and truck

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Hi,

CB radios use a frequency range and technology that is prone to noises both atmospheric, and man made. The height and gain of your new base antenna may produce more static than you may have noticed before. The question is 1) is the antenna close to any power lines to your home, 2) do you notice any increase or decrease of received signals compared to your mobile, 3) is the static steady or does it come and go.

Posted on Nov 12, 2008

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My cobra 18 wx st comes on and goes tru all channels but has no noise at all coming thru it. none of the signal strength lights come on or anything. its brand new.


Sounds like a antenna issue. Make sure coax is in good order.and antenna is connected properly. You might have to get a "swr" meter to put in line between radio and antenna to make sure antenna is "tuned" to were the radio is operating. Radio shack sells a ok low budget swr/power meter.

Nov 09, 2012 | Cobra 18 WX ST 40-Channels Base CB Radio

1 Answer

Why does my moonraker cb change channels by itself.


This can be caused by RF feedback. RF is radio frequency energy - the same energy that your transmitter puts out onto the coax cable & antenna.

RF feedback is similar to audio feedback in that some of the output re-enters the circuit in a place it doesn't belong or is designed. RF feedback is a direct result of a poorly matched antenna system as shown by an SWR meter. A standing wave ratio or "SWR" of 2.0:1 - 2:5.1 (read this as: two point zero to one and two point five to one) or greater is generally accepted as the worst SWR a transmitter can tolerate - but also requires lowering RF power (wattage) to continue transmitting.

Some common sources of high SWR are: 1) wrong cable type (usually a 50 ohm cable is used), 2) damaged cable, 3) untuned antenna, 4) damaged previously tuned antenna, etc. The SWR of an antenna system should be checked and adjusted as needed to assure maximum power transfer to the antenna. If the system has a high SWR, the antenna reflects some of the RF energy back on the coax - into the radio. The effects can be tingles / burns on the lips - if using a mic with a metal guard, noise, and erratic operation of some rig settings. This energy is unexpected and can cause all sorts of strange radio operations and is not an uncommon occurrence in a situation such as this.

You can correct this problem by purchasing or borrowing an SWR meter or bridge designed to work in the range of frequencies that your CB uses. Follow the directions included to lengthen or shorten antenna elements as needed. An ideal SWR is 1.1:1. Generally, any value of SWR less than 1.5:1 is considered very good. A check of SWR on the low, mid and highest frequencies will give you an idea as to how well the antenna works on the frequencies you use, and let you know which frequencies you should avoid.

Good luck!

Apr 21, 2012 | CB Radios

1 Answer

How to do basic set up


Is this setup in your car or at you home? Many use a mobile CB in there home off a power supply. First your antenna is a major part of your set up. Spare nothing when buying this. I recommend Wilson 300 or higher for the mobile and IMAX 2000 for home. Some Wilson antennas tune easier than others. Follow the instructions that come with it and ask me if you are unsure. A good 50ohm coax is necessary too. RG58 or better. For just the CB in the mobile RG58 will do just fine. At home I use RG213U. Now we get to your SWR (Standing Wave Ratio) which deals with return loss and reflection coefficient. To high of an SWR and you will lose a lot of your signal and you can burn up your radio. You will need to purchase an SWR/watt meter and put it inline. The coax from your antenna will run into your meter and then run another coax from your meter into the radio and follow the instructions on how to adjust and check your SWR. So now we are at the point where your set up is properly set up.

Feb 01, 2011 | Midland CB Radios

1 Answer

Having trouble setting swr .moved anttena up and down 1/4 inch at a time and there is no change


There are several things that can cause you not to be able to get an acceptable SWR.

The first is the most obvious. Poor antenna, or bad coax. Make sure your coax is good. Make sure the antenna is mounted in a good location.

Some things I have seen that cause this problem.

  • Wilson Little wil, almost impossible to get under a 1.6 SWR.
  • Fiberglass antenna's, a break in the wire near the top of the antenna. Will show the antenna as being too short, and adjusting the top will do nothing. This antenna is no good.
  • Common mode current. This is when the RF is traveling back down the outside of the coax, and or causes the coax to act like part of the antenna. SOLUTION. As close to the antenna as you can, take 6 to 8 inches of coax, and coil it into a tight coil, about the diameter of a spray paint can. In fact using a spray can to wrap the coax around works well. Use electrical tape to secure the coil so that it will stay tight and uniform. This will stop common mode.
  • missing foil/vinyl membrane on bottom of magmount antenna. This is essential for the antenna to see ground plane.
  • bad connections on coax connector.
  • Cracked isolator on stud mount.
  • incorrect procedure for taking SWR reading.
  • Poor location of antenna. E.g. antenna's load not above roof of vehicle.
  • Incorrect length whip being used.
  • corrosion of any part of the antenna system.
There are some cheap antenna's out there that you just can't get lower then say a 1.5 or worse, like the wilson little wil. Wilson makes great antenna's. The 500, 1000 and 5000, as well as their silver load antenna's are excellent. I have been able to get them all to at least a 1.1 SWR, and some like the 5000, and silver load fiberglass whip to 1.0 using an analyzer. The Little will is just a poor antenna. Anything under 2.0 SWR is okay of a barefoot radio, although I don't like going over 1.5 my self. A barefoot radio, will do a 2 swr all day. If the radio is stock, and not peaked and tuned, 2 swr is fine and won't hurt the radio.

You should always try to get the lowest SWR that you can in any case. The lower the SWR, the more RF energy is leaving the antenna. As well, receive will improve the closer you get to a perfect match. This is known as being "On Que".

Check everything I have listed that applies. And if nothing fixes it, you may want to try a different antenna. Some antenna's just don't work well on certain vehicles.

Oct 13, 2010 | Cobra 29 WX NW ST 40-Channels Base CB...

1 Answer

We are trying a radio check for a mirage 66 but the static only goes away when we turn the squelch all the way down and we can't hear anyone


Sounds like you have a lot of interference. Could be something in the vehicle causing all the noise. Try it with the engine off. Also make sure the antenna system is correct. for example, coax good. antenna grounded. SWR low. etc.

Oct 02, 2010 | Galaxy Radios DX-66V Base CB Radio

2 Answers

Cobra NW LTD CB radio


start out by getting a good antenna like a wilson or k-40 if your using it on a big rig make sure its a metal mirror and door a lot of big rigs use fiberglass and thats a nono you must get a no ground plane antenna...its all in the antenna...good luck doc's cb shop ny

Apr 09, 2008 | Cobra 29 NW CB Radio

2 Answers

SWR calibration waaay off the chart


You are using an inline swr meter to set your swr right, not looking at the meter on the radio? Here is the process to set swr on an antenna:

You must have an inline swr meter, which can be purchased online or from a truck stop. The ones at truck stops are cheap ones, but will do the trick for the most part.

You connect your antenna 18ft coax to the antenna plug of the swr meter, and a jumper coax (any length) to the transmitter plug of the swr meter and then to the radio.

Close all doors and make sure no one is messing around with the vehicle or antenna. You must be set up as you would normally be transmitting.

Now set your cb radio to channel 40 and your swr meter to fwd. Key up your microphone1.gif and at the same time turn the set knob on the swr meter until the needle is at the line that reads set. Unkey your mic and set the the swr meter to ref. Key up again and note what your reading is. Now leave the swr meter in ref and turn the cb to channel 1. Key up and take your reading. If the reading on ch 1 is higher than ch 40 you must raise the stinger on your antenna. If ch 1 is lower than 40, you lower your stinger. You are trying to get lower than a reading of 3 and as close to 1.5 as possible. If you lower your stinger as far into the antenna as it will go and you need it shorter, you cut the bottom of your stinger no more than 1/2" at a time, and recheck your swr reading after each cut.

Once you have gotten the best reading you can, connect your antenna directly back to the radio.

The setting of your swrs is to make your antenna as efficient as possible, by trying to get it as close as you can to a 50ohm impedance. THE ONLY PART OF YOUR SYSTEM THAT CAN CHANGE YOUR SWR IS YOUR ANTENNA, not your coax and not your radio. Your radio and coax can give you false readings, but only the antenna can actually change the swr.

On the swr meter, the fwd/ref switch stands for forward (power that is being transmitted out) and reflected (power that is reflected back into the radio.

Just for information sake, the swr cal switch on your radio is used to set the meter to reflect the swr that your antenna is set at. The meter on your radio is like a dummy light on your car. ONCE AGAIN, YOU CAN NOT SET YOUR SWR ON YOUR RADIO, only the antenna.

Dec 29, 2007 | Connex 3300 240-Channels Base CB Radio

2 Answers

Galaxy DX959 CB radio reception and broadcast


You Need to check and set you SWR on the antenna system. You may also have a bad coax or the ant studs ( mounting hardward ) for the antennas may be bad. It definally sounds like an ant/coax problem Good Luck
Ed
NC Electronic
Mills, Wyoming

Dec 08, 2007 | Cobra 18 WX ST II 40-Channels Base CB...

3 Answers

Connex 3300hp radio


Hi,

Based on your post/description:

1. how do i set the swr
Normally SWR are calibrated on your operating channel (where you usually stand-by). This is to maximize transmit power and receive sensitivity. To set SWR, switch to channel of your choice, switch SWR control to CAL, key or press PTT, while pressing PTT rotate ADJ knob until max deflection of needle on meter, release mic, switch control to SWR, key/press PTT, needle reading/deflection is SWR for that channel.

I would suspect that your SWR will vary from your current 1.4. This is because you have too big excursion of channels (240 channels).

2.reading a 1.4
This reading is good enough and should do. However as earlier stated, you seem to have 240 channels which would mean that your radio + antenna moves in a wide bandwidth and since the antenna tuning is affected by frequency, your SWR will also be affected by channel.

Best if you can further lower it down.

3. some cb cant get me
This is because the standard CB radio is only 40 channels. The next would be a 80 channel and then 120 channels.

4. is it my radio
Yes, you have a wide coverage radio almost an extended 10 meter rig.

5. do i have to set my radio on high or low to set my swr
I will assume you are referring to power output, set it to HIGH when doing SWR calibration

Hope this be of some help/idea. Pls post back how things turned up or should you need additional information.

Good luck and kind regards.

Nov 08, 2007 | Connex 3300 240-Channels Base CB Radio

3 Answers

Red ant light


The red light always comes on while mic is keyed. It is designed to do that. It will blink on and off while mic is keyed if there is a SWR problem. This is explaned in operaters manual.

Sep 24, 2007 | Magnum S9 Base CB Radio

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