(Newbie) Advices on antenna and TX on President Jackson (Silver Edit.)

[albatros]

Hello everyone. I guess I should first introduce myself. If you'd like to skip the introduction, please continue from the second paragraph. I am a prepper and a CB enthusiast living in Ankara, Turkey. I have always wanted to host an amateur (pirate) radio station of my own but after I have turned 18, I have realized that it wouldn't be that good of an idea after all -with the legal limitations-. Therefore I carried on using my Motorola T4500 GMRS walkie talkies. However, all these didn't stop me and few days ago I did my first CB radio. I will be using it both mobile and at home, so I need some advice about that.

To start by, the CB radio I bought is President Jackson (Silver). I am using a magnetic car antenna with that device (which came with it). When I am in car, power socket is not a problem since there is the good old lighter plug and when I am home I am using a home brew 12VDC 16AMP computer power supply. However, the antenna became a little of a problem here. I live in a flat (5th floor) and don't have any balconies, etc. at all. Therefore I am attaching my car antenna to the metal mounting pipe of my satellite dish and connected the dish to the radiator in the room (for ground). I have made a small coil around the antenna and tested the transmission with a multimeter (on AC Volts). There is transmission (generating around .9 VAC). However, I am not sure if I am doing something wrong since I don't receive any reply on any frequencies (A,B,C,D and E bands, 1-40 channels and +10KHz 1-40 channels on FM, AM, USB, LSB). As far as I know, the output of the head unit is modified and increased to around 40 watts. Therefore I expect somebody to hear my transmission and reply, but nope. I started to think that I am doing something wrong (duh!). Therefore I need all kinds of advice I can get. And I also have some questions such as which transmission mode should be chosen for long range radio communications and which Band/Channel pairs I would be most likely to receive a transmission.

Sorry for the long post, I will be ending it with some photographs of the setup. Sincere thanks to everyone trying to help.

Images: https://drive.google.com/open?id=0B0n2wkH3pLNcdzF0a2xZdE9ZbUU

 

[robertmac]

Hello. First I hate to see the use of "amateur [pirate] radio station". In North America and most of the world, certified amateur radio operators are not pirates if used within the amateur bands for which they have obtained their certificate. This varies from country to country and I know nothing about the regulations in Turkey. I am not fully aware of CB regulations in Turkey either [and there is a difference between amateur and CB radio]. You mention channel and frequencies but do not really indicate the frequencies [A, B, C etc. bands] mean nothing to me. They could to someone familiar with the radio. Channels 1-40 could apply to the 11 meter frequencies that are in use in North America. 40 watts is not authorized in North America on the 11 meter band. Now if you are talking about 10 meters that is another story. Again, not being familiar with Turkey, I do not know how many active CB users you have for the 11 meter frequencies. As for 10 meters, this again depends on licensing and how many in your country are licensed. If you are wondering about long distance [greater than 100 miles] this largely depends of propagation [atmospheric conditions] which vary day to day. And time of day. So I am not clear if you are trying to talk to locals or distance, what frequencies are you using, and time of day. Do you receive anyone talking [skip] on 11 meters especially during the day light hours. Have you looked to see if your signal is getting reflected back into the radio which will limit how far it gets out? A cigarette plug in and 40 watts output might blow the fuse when used in your vehicle. Connecting directly to the battery [with fuses on positive and negative] might be better. Your antenna may not be sufficient for 11 or 10 meters. Others can comment on this as I do not use 11 meters anymore. Generally it requires a good ground plain [such as the top of your car]. So you may need to put radials out. Modes: really depends. the 11 meters is AM, or Lower side band generally, but AM, Upper and Lower are used. I don't think FM is allowed on 11 meters and is not used a lot on 10 meter. Again, AM and generally upper side band are used on 10 meters with some FM used on the higher frequencies on 10 meters [above 29 MHz]. Someone may talk about the "pirate frequencies" used, but I am not going there. Others will have their say here, but by getting licensed a lot of your questions will get answered.

 

[teufler]

what Robertmac suggests, do you have an swr meter, or is there a setting on the radio that gives you an swr reading. This will indicate power going to the antenna or getting reflected back. If too much, you might have an alc circuit that cuts your power to protect the radio. I too don't know about the Turkish Radio rules.

 

[albatros]

Sorry for the information I skipped. In Turkey, CB radios are allowed to broadcast in C and D bands in FM and SSB. Also, it is allowed to use E band for international communications purposes up to E 12 if and only if you are using AM. There were legal limitations on the maximum output power (it was limited to 4W by 1981). However these rules were never obeyed since there were no legal authorities checking on these. Therefore, now a CB user with no license can use up to 40 watts TX (without penalties, state kind of excuses up to that point) in C 1-40, D 1-40 and E 1-12 bands. I have also modified my car to have a button and relay controlled bypass line (with 8AWG cable) to the original ligher plug so that if I switch it on, I can get up to 5 Amps 12VDc without frying anything.

As for the SWR, I don't have a SWR meter if the dial on the receiver is not one (on the top it says transmit power followed by a green line with a red ending and on the bottom is dB).

 

[bharvey2]

Your description of the antenna as used in your apartment confuses me. You say that you use a satellite dish as part of the antenna. Is that on the roof or is it mounted to the wall outside of your window? Given your height of 5 stories tall, I think your best bet may be a vertical dipole antenna. The length of the dipole would be dependent upon the frequencies you are using. Your terminology of Bands A, B, C, or D won't likely be understood by most people as CB radios may use different frequencies depending upon the country of operation. The frequency in MHZ would be better. If you can provide that, you might be able to get a more practical suggestion to resolve your problem.

 

[albatros]

Your description of the antenna as used in your apartment confuses me. You say that you use a satellite dish as part of the antenna. Is that on the roof or is it mounted to the wall outside of your window? Given your height of 5 stories tall, I think your best bet may be a vertical dipole antenna. The length of the dipole would be dependent upon the frequencies you are using. Your terminology of Bands A, B, C, or D won't likely be understood by most people as CB radios may use different frequencies depending upon the country of operation. The frequency in MHZ would be better. If you can provide that, you might be able to get a more practical suggestion to resolve your problem.

Okey then, the frequency range I am planning to use is between 26.065MHz and 28.305MHz. The most used frequency band within these will be 26.965MHz to 28.015MHz

 

[albatros]

Update on topic: I have managed to program a Raspberry Pi to transmit audio on the frequency of 27.215MHz FM (TX Power <0.1W). I have successfully received the transmission with the President Jackson from about 100 meters. I guess I will be going for an inverted V antenna tuned to 27.405MHz (specs down below).

Height of the top point of dipole: 201cm - 79.133inch
Length of copper cable: 260.5cm-102.559inch (for each side)
Height of the side support poles: 70 cm-27.559inch (for each side)
Angle of the antenna lines to the normal: 60 degrees each (total 120 degrees)
Insulator to be used for the poles: Zip tie
Pole material: PVC Tubing
Antenna cable (from TX to antenna): 9meters-354.330inch of RG58

ASCII Drawing in attachment

 

[albatros]

Update 2:
I have managed to make the ASCII drawn antenna (designed for 27.305MHz) with 1meter-39.3inch PVC pipes. Main pole is made by 2 nested pipes with a T connection on top. Both support poles and T connector are drilled to insert zip ties to create an insulation. Antenna cable is made from 3mm-0.11inch diameter stainless steel wires with carabiner attached to both ends. Carabiners are attached to the zip tie insulators. I am waiting for the SO-239 connectors (arriving tomorrow) to complete it. When it arrives, I will attach to connector to the middle of the T connector and attach 12AWG multi strand copper wires from them to the carabiners (I don't know how yet, I only have a soldering iron and it is pretty hard to solder on polished stainless steel). I will probably use a keychain ring and squeeze the cable in between and connect the ring to the carabiner. As far as I have learned from an EE engineer (specialized in antennas), the material antenna cable is made from is not very important for frequencies as low as 30MHz. The conductivity starts playing a big role in up around 100MHz. Best part of this antenna is that it can be disassembled very easily and becomes 4 poles each are a meter high. Easy to store and easy to use outdoors. However I will still be researching for an appropriate antenna for my flat.

 

[bharvey2]

Albatros, you are on the right track. A 1/2 wave dipole will consist of two 1/4 wave conductors. To determine your length, find the center frequency that you want to use. It looks like you've arrived at that frequency of 27.215mhz. Next you divide 468/27.215 = 17.196 ft. Or the total length of the 1/2 wave dipole is 17.196 ft. Divide that by 2 again and you have 8.598 ft. per side. So, two conductors 8.598 ft pointed in opposite directions. One is connected to the center of your coax, the other connected to the shield. Ideally, you would use a 1 to 1 current balun to stop the coax shield from radiating RF in your apartment. For CBs, the antenna would normally be mounted vertically at least here in the U.S. If it is possible, mount it that way. You will lose signal strength if you mount it horizontally. There are commercial versions of what you are trying to accomplish. MFJ has a product called a HamStick that is available in 11 meters.

 

[albatros]

Albatros, you are on the right track. A 1/2 wave dipole will consist of two 1/4 wave conductors. To determine your length, find the center frequency that you want to use. It looks like you've arrived at that frequency of 27.215mhz. Next you divide 468/27.215 = 17.196 ft. Or the total length of the 1/2 wave dipole is 17.196 ft. Divide that by 2 again and you have 8.598 ft. per side. So, two conductors 8.598 ft pointed in opposite directions. One is connected to the center of your coax, the other connected to the shield. Ideally, you would use a 1 to 1 current balun to stop the coax shield from radiating RF in your apartment. For CBs, the antenna would normally be mounted vertically at least here in the U.S. If it is possible, mount it that way. You will lose signal strength if you mount it horizontally. There are commercial versions of what you are trying to accomplish. MFJ has a product called a HamStick that is available in 11 meters.

Thanks @bharvey2 ! I am currently living in Turkey and therefore it would be practically impossible for me to get one of those commercial antennas. It is strictly prohibited for individuals to import telecommunications and radio communications products to here. Therefore I will have to make my own antenna in any cases. However I have an idea on mind for a full wave antenna. Do you think that an antenna made out of insulated copper wire, nailed to the wall in s bends (in the attachment) work in some way? The dipole I made was for camping use, I am planning to test it as soon as possible but having an antenna at home is still a dream. Cheers

 

[bharvey2]

Albatros, an antenna consists of two parts: the radiator that we normally consider "the antenna" and some sort of ground. In the dipole that I described, you can see both components. In your vehicle, the body of the vehicle acts as the other component. Without any test equipment, I think you'll have trouble constructing many types of antennas. If you can get hold of an SWR meter you can build and adjust the dipole mentioned above. Given your apartment height, I think you'll be quite successful with that type of antenna. When I was a kid I built a 1/4 wave ground plane CB antenna (four radials at 90 degrees to and mounted under the vertical radiator) and it did very well. I only had an SWR meter. The dipole and ground plane antennas will function without matching components. Other antennas types may not. If you get too far off in building an antenna that doesn't match the impedance that your radio is expecting (50 ohms) you could damage your radio. You could try a full wave antenna (about 35-36 feet) for receive but I would not try to transmit.

 

[albatros]

Albatros, an antenna consists of two parts: the radiator that we normally consider "the antenna" and some sort of ground. In the dipole that I described, you can see both components. In your vehicle, the body of the vehicle acts as the other component. Without any test equipment, I think you'll have trouble constructing many types of antennas. If you can get hold of an SWR meter you can build and adjust the dipole mentioned above. Given your apartment height, I think you'll be quite successful with that type of antenna. When I was a kid I built a 1/4 wave ground plane CB antenna (four radials at 90 degrees to and mounted under the vertical radiator) and it did very well. I only had an SWR meter. The dipole and ground plane antennas will function without matching components. Other antennas types may not. If you get too far off in building an antenna that doesn't match the impedance that your radio is expecting (50 ohms) you could damage your radio. You could try a full wave antenna (about 35-36 feet) for receive but I would not try to transmit.

Oh then, as far as I understand i will be safe with a dipole or ground plane even without a SWR. Am I right? And for the SWRs, would the Chinese devices work fine?

 

[bharvey2]

If by Chinese devices you mean SWR meters then yes, they should be fine. If you buy one it should cover the the frequency and power that you intend to work with. Also, it is best to test SWR at low power levels first. Then if you can get your SWR below 2:1 you should be safe. The best way is to test SWR at the ends of the frequency range and the middle of the frequency range that you intend to use. In doing so, you can determine whether your antenna is right or needs to be adjusted in length. It is best to start with your antenna too long and then trim it by small amounts to adjust it properly.

 

[albatros]

If by Chinese devices you mean SWR meters then yes, they should be fine. If you buy one it should cover the the frequency and power that you intend to work with. Also, it is best to test SWR at low power levels first. Then if you can get your SWR below 2:1 you should be safe. The best way is to test SWR at the ends of the frequency range and the middle of the frequency range that you intend to use. In doing so, you can determine whether your antenna is right or needs to be adjusted in length. It is best to start with your antenna too long and then trim it by small amounts to adjust it properly.

Thanks for the advise. I have bought eBay item number 181861562117 as SWR meter. Up to 100W and the 3MHz-30MHz frequency would totally suffice my needs for now. As soon as it arrives, I will try out new antennas. Do you think I should wait for that to arrive before I test skipping with my inverted V dipole?

 

[bharvey2]

Albatros, you can certainly try it in receive mode. A rough way to adjust the antenna is to place the radio on an inactive channel, turn down the squelch and adjust the antenna length until you get the greatest amount of noise. If your antenna is away from any type of metal surfaces and of the approximate length, you could try it on low power and use the CBs built in SWR meter. Just transmit at the lowest power setting and for very short periods of time. (1-2 seconds). As I mentioned above, I thing you will get better results if you can mount it vertically rather that in a "V" assuming that is how others in your area do it on CB.