This blog was created to share my projects, ideas, and experiences in amateur radio with other operators around the world who also enjoy this wonderful hobby.

Sunday, July 22, 2012

Baofeng Speaker Microphone Compatibility

Photo 1
 The Baofeng speaker microphone was received this week. I tested compatibility with the UV-3R and then
with the BF-U3, UHF model. The speaker microphone has very good transmit and receive audio with the UV-3R as reported by amateur operators on various repeaters locally. No push to talk issues were observed during operation. The speaker microphone audio response is a little on the high side (bright) for my taste,but overall quality is acceptable. I prefer the UV-3R internal speaker response and quality, but the brighter pitch of the speaker microphone is an advantage when operating in noisy environments.

Photo 2
 During transmit, no PTT issues were observed with the speaker microphone. In this photo the UV-3R is shown transmitting in high power. The included earphone / mic supplied with the radio does not suffer from the RFI issue reported with some UV-3R's. It  keeps the radio in transmit when operating on high power in the VHF band. I found a video on YouTube from SP3PWJ, showing a modification ( adding a disc capacitor to the earphone / mic ) to cure the RFI issue. This only has been reported in some radios, and only when using the supplied earphone / mic. The video is in polish, but has captions in English.

Photo 3

The Baoefeng UV- 3R's speaker microphone configuration. When viewed in this position and from left to right, tip is speaker out, ring two is microphone input, ring one is PTT input and the sleeve is common/ ground. On this microphone, the impedance of  the speaker is around 8 ohms and the microphone element is 1,500 ohms. This was calculated by the dc resistance readings obtained with my DMM (digital multimeter). 

Photo 4

The same tests were performed with the BF-U3 UHF radio. According to suppliers in Hong Kong and China, speaker microphone operation is not possible with the BF-U3. I discovered that it works with the speaker microphone, but the audio is weak. When tested with the supplied earphone / mic, the audio is loud and clear. I measured the dc resistance of the earphone/mic and found that it is above 30 ohms. The BF-U3 speaker microphone jack impedance is designed for higher impedance and does not work with the 8 ohm impedance of the speaker microphone. Adjusting the volume had little effect on the received audio when using the speaker microphone. Transmit audio was not a problem with the speaker microphone, on air reports were as good as with the UV-3R.

Photo 5

The BF-U3 is shown transmitting on high power with the speaker microphone. No PTT issues were observed, even with the microphone cable in close proximity to the antenna. The transmitted audio quality is the same as with the UV-3R , as reported by tests performed on the air,with other amateurs via repeaters. The speaker microphone provided better audio quality than the supplied earphone / microphone.

Photo 6

The BF-U3 receiving with the speaker microphone. The received audio quality is acceptable but very weak. In conclusion, the reason for this difference in volume is, the impedance of the speaker microphone ( 8 ohms) when compared to the higher impedance (30 ohms) of the supplied earphone microphone. Some vendors are selling speaker microphones and they claim compatibility with the BF-U3. I have tested different microphones from different suppliers and the results have been similar. This speaker microphone was purchased on E-bay from Solid Radio in Hong Kong. They cost less than $15.00 including shipping. There are other more expensive ones, including waterproof  versions, but they cost more than the radio alone. The other UHF mini hand held from Baofeng, the BF-U8 also suffers from the same speaker microphone compatibility. I will keep the speaker microphone for use with my UV-3R's and will use the BF-U3 with its internal speaker or with the supplied earphone microphone. This information was added to my blog as a complement to the Baofeng UV-3R and BF-U3 reviews and observations published earlier. You may find a  very nice compilation of information and FAQ's for the UV-3R . Any questions or comments are welcomed via e-mail, as well as your tests and observations with  Baofeng radios.

Sunday, July 15, 2012

Baofeng BF-U3 UHF 16 Channel Mini Hand Held

photo 1
The Baofeng BF-U3 UHF 16 channel mini hand held is a two watt transceiver covering from 400 to 470 mhz. The size is similar to the popular UV-3R , uses the same battery and accessories but can not be programmed from the front panel. The BF-U3 can be set to low power operation (less than 1 watt) with the programming software. The programming cable and software is not included with the radio.

photo 2

The BF-U3 package includes, radio, UHF antenna (SMA male), 3.7 volt lithium ion battery ( 1500 ma.),
usb power supply charger, usb charging cable, battery charging cradle, belt clip, in ear type earphone /mic with ptt , user's manual and lanyard.

photo 3

The Baofeng BF-U3 mini hand held compared to the dual band model, UV-3R. The case is about the same size as the UV-3R but there are no front panel buttons , just the left side buttons and the channel selector knob on top.The antenna supplied with the BF-U3 is a single band antenna for the UHF band (400 - 470 mhz.)
The antenna supplied with the UV-3R is longer and is a dual band antenna. On older versions of the UV-3R , Baofeng supplied two antennas, one for VHF and one for UHF. The size of the UHF antenna on the older UV-3R's is about the same length as the one on the BF-U3. The performance of both antennas is the same.

photo 4    

 Front view of both radios. Notice that on the BF-U3 the speaker is located at  the top of the radio case, on the UV-3R the speaker is located at the bottom. Both radios use the same type of antenna connector ,the SMA male , any aftermarket SMA male antenna will fit. I have obtained good results on both models with the Nagoya NA-701 and the NA-773.

photo 5    
The back view of the BF-U3. The battery cover is the same as in the UV-3R and it also uses the same battery, a 3.7 volt, 1500 ma. lithium ion battery. The belt clip attaches to the back of the radio with one phillips screw. Battery contacts are located on the top of the metal chassis of the radio , the battery cover is secured in place with a sliding lock on the bottom of the case. Both , the cover and the battery can be removed with the belt clip attached to the radio.

photo 6

A close up view of the back . The metal chassis on the BF-U3 and the UV-3R are used as a heat sink for the final amplifier transistor, it is normal for the radio to heat up during  long transmissions on the two watt,  high power setting. The temperature never rises to an uncomfortable level , like in some five watt handhelds. When operated in the low power setting , it is warm most of the time, even in long transmissions.

photo 7   

Top view of the BF-U3. The antenna connector to the left, the built in torch led flashlight and the channel selector knob. On the dual band UV-3R the channel selector  knob is used for various functions, on the BF-U3, it is strictly for channel selection. When the knob is pulled, it selects your operating channel , from one to sixteen. When the knob is pushed , it locks the radio in the channel selected. When selecting channels ,the radio will announce the channel number in voice.  Below the channel knob is the TX / RX led, it glows green when receiving a signal , and red when transmitting.

photo 8

Right side view of the radio. The speaker microphone connection requires a four contact , 3.5mm plug. The radio includes the earphone/mic unit with push to talk switch. The programming cable is connected to the same jack. The cable is not included but it can be found on the internet from different suppliers , including E-bay. I ordered one some time ago from , to program the Baofeng UV-3R, it is the same cable the BF-U3 uses. . The programming software is different from the one used on the UV-3R and can be downloaded free from  409shop also . The lower connector is for the dc adapter charger. The battery can be charged using the supplied usb power supply (120 vac to 5 vdc) or from any available usb port with the supplied cable. It can be charged inside the radio or outside on the included charging cradle.

photo 9
Left side view of the radio.From top to bottom, ptt switch, M/L button and P/V button. The ptt is used to key the transceiver, when the external earphone/mic is used the radio's ptt switch still works.The M/L button is used to activate the torch led flashlight or to open the squelch (monitor). The P/V button is used to turn on or off the transceiver, it needs to be pressed for 2 seconds to either turn on or off. When turned on, the command is announced in voice thru the speaker, also it will announce in voice when powering off. The voice can be changed from chinese to english with the programming software. Pressing the P/V button rapidly will increase the volume in pre- determined steps. In order to set the volume to minimum , you need to cycle through  all the steps , reach maximum and then start from minimum again.

phone 10  

Rear view of the Baofeng BF-U3. Note the similarity with the dual band model ,the UV-3R.
The belt clip is attached to the radio with a single phillips screw. Both the battery cover and the battery can be removed from the radio with the clip installed. Be careful as the belt clip is thin plastic and is not spring loaded , it can break easily.

photo 11

Front view of the Baofeng BF-U3 while receiving a signal. The receive led will glow green. The metal on the front panel bottom is not real metal, it is a chrome plated sticker . The received audio is better than the audio on the UV-3R dual band model . This is related in part to the acoustics of the radio case and to the fact that the speaker is located on top of the front panel and not the bottom. Both models have 500 mw. audio output power.

photo 12

The Baofeng BF-U3 transmitting. The receive led changes from green to red, ptt is possible from the radio's ptt switch even when the earphone/mic is used. According to several vendors on the internet, the BF-U3 does not support speaker mike operation. With the included earphone /mic it works ok. I am still waiting for a mini speaker microphone I ordered last week to arrive for my UV-3R. I will test the speaker microphone once it is received with the BF-U3 in order to confirm this issue and will post or edit the information here. The power settings need to be programmed with software , either high or low, for each one of the sixteen channels and can not be changed from the radio.

photo 13   

Front view of the radio with the stock UHF antenna attached. Next to it , the Nagoya NA-773 dual band telescopic antenna. Reception is acceptable with the stock antenna, local repeaters can be accessed ok, at even the low power setting. I have found that  most mini handhelds like the Yaesu VX-3R , Icom IC-Q7A and the Baofeng's receive better when you are holding them in your hand. The human body by capacity couples to the radio , in most cases improving reception . When you place the radio on  your desk ,for example , sometimes reception is marginal. This is noticed mostly on the vhf frequencies and it is caused by the size of the radio.. The mini handhelds metal case is not large enough to provide an  adequate counterpoise on the vhf frequencies. I remember a company sometime ago ,selling a "rat's tail", it was a counterpoise wire that was attached to the antenna connector down the back of the hand held. It improved the reception and probably the transmission ,because it provided a quarter wave counterpoise radial to the transceiver. In real life or daily radio activity this is impractical , but it clearly explains the problem with the mini hand held's insufficient counterpoise. A longer antenna in most cases improves the reception , I have obtained good results on both radios, the BF-U3 and the UV-3R with the Nagoya NA-701 and the NA-773. The 773 is a dual band telescopic antenna and provides superior reception on both radios. The 701 is my choice for everyday operation as it is not too long. You have to compare and experiment with the different models available , your results may be different. In my tests the receive sensitivity of both radios is about the same, the BF-U3 when receiving fades more than the UV-3R ,but this has a lot to do with the short antenna. Using a longer antenna , improves the reception. RFI immunity on both radios is also the same on UHF. With the UV-3R operation on VHF near a computer,  monitor or  near a wireless router is impossible. This is related in part to the simple, zero IF, dsp design of both transceivers.

photo 14

This is the view of the BF-480 programming software on the computer screen. The program can be downloaded free from It is not the same software used with the UV-3R so be careful. The first step is to configure the comm port for the usb cable to Baofeng mini plug. In my case I am using comm port number four. Start entering your receive and transmit frequencies ,starting with number, one until you reach channel number sixteen. Also enter the transmit pl tone or DCS , the transmit power (high or low),wide or narrow deviation and if you want to add the channel to the scan group. The busy lock out if left on, will prevent the radio from transmitting while a  channel is busy. If you don't want this feature, change the setting to off. Once you have all your information entered correctly, click on the program tab ,and in the pop out  window, click, write to radio. A progress bar will appear while the radio is programmed. Once programmed ,you can save your programming information in a file on the computer. If you want to see what is programmed, click on the program tab and select , read from radio. Programming all the channels is not needed , the radio will emit a constant beep when you select a channel that is not programmed.

photo 15

This is the view of the BF-480 programming software screen , with the programming I did on my Baofeng BF-U3. There are not many active repeaters in Puerto Rico that I am able to use with two watts from the capital (San Juan). I was able to test twelve repeaters that were  within range , programmed those frequencies and left four channels empty for future use. The software is very user friendly and the programming process can be completed in very little time, if you have the list of frequencies already organized. On the Baofeng UV-3R there are a total of 99 memory channels, it will take more time to program the complete set of memories on that radio. If you have any questions or comments regarding the Baofeng BF-U3 uhf mini radio or the UV-3R , subject of an earlier blog entry, please contact me via e-mail. I hope this information helps deciding which radio is a better option in your particular application and clarifies the programming process with the BF-480 software.

Wednesday, July 11, 2012

Dipole Antenna Construction Ideas

Step 1
The materials needed for the dipole antenna construction are shown above. We are going to use the dipole antenna center insulator built earlier. The other materials are, 26 feet of #12 or #14 stranded copper wire, two pieces of heat shrink tubing 1/4" diameter by 1- 1/4" long. The length of the wire sections is calculated using the formula ,468/F(MHz). Approximate wire lengths  for the popular Amateur Radio bands will be given at the end of the building process. The dipole we are about to build is for the 15 meter band. From the formula 468 divided by 21.0 mhz = 22.28 feet. Divide the result by 2 to get the lenght of each side of the dipole. The wires need to be longer to compensate for the connection loops and adjustments. Cut each side to 13'  to be safe.

Step 2
 Start by inserting one end of the copper wire thru the top of a crimping ferrule, then go thru the eyebolt, and back thru the bottom of the ferrule making a 2 inch loop. Move the ferrule as close to the eyebolt as possible, but don't crimp it. Crimping will be done later.

Step 3 
Insert a piece of heat shrink tubing thru the wire on the dipole center insulator. The length of the tubing is 1-1/4 " and the diameter is 1/4 ".

Step 4
 Now, strip about 1/2" from the insulation on the antenna wire and the center insulator wire. Apply 60/40
rosin core solder to both wires and wait for the solder to cool.

Step 5
 The next step is to insert each wire into the splice cap. It is a good idea to apply solder to the inside of the splice cap , this will make soldering  the wires easier. Apply solder to the splice cap and the wires . Do not crimp the splice cap over the wires because corrosion will damage the connection in little time, always use solder. This splice cap can take more than one wire so it is possible to build a two band or a three band dipole, with a single center insulator. Up to three antenna wires plus the center insulator wire will fit inside the copper splice cap. If #12 gauge wires are used it will only take two plus the center insulator wire. A larger diameter splice cap can be used if  # 12 wires are preferred for the construction.

Step 6
 Wait for the splice cap and the wires to cool and slide the heat shrink tubing until it covers evenly the splice
cap and the wires. Repeat the same steps on the other side of the antenna. It is a good idea to verify continuity of your connections with a VOM (volt ohm meter) or a DMM (digital multimeter) before applying
heat to shrink the tubing. Good quality electrical tape can be used instead of the shrink tubing as well as liquid tape (available at Home Depot) or silicone sealant.

Step 7
Now it is time to install the end insulators to each side of the dipole. The process is similar to the one explained for the center insulator ferrule installation. Do not crimp the ferrule on the dipole ends. This will be done at the end when you install and test the antenna with an antenna analyzer or SWR meter. The ends can be adjusted for minimum SWR by adjusting the length of the antenna wires. This is easily done on the dipole ends.
When the antenna is tuned for the operating frequency or frequencies, then you crimp both ferrules at the ends.The center insulator ferrules can be crimped after the previous steps are completed.

Step 8 
A close view of the crimp splice cap connectors used for the center insulator wire connections. The are made by Buchanan, the part number is 72400, the package contains ten pieces. They are available at  Home Depot for a few dollars. If the connectors are not available it is possible to solder both wire connections with a good quality 60/40 rosin core solder and then  protecting the connection with shrink tubing, electrical tape, silicone sealant or liquid tape. Remember, the idea of the splice cap is to fit more than one wire at a time, making it possible to build a two or three band dipole and at the same time protect the connection from the elements.

Step 9 
 The ferrules are made of aluminum, the internal diameter is 1'8". They will take #14 and #12 gauge copper wire. They look similar to a binocular ferrite core. They are available at Home Depot and other hardware stores. Four ferrules are required to complete the antenna, each package contains two ferrules. I have seen them  listed for sale on E-Bay also at fair prices.

Step 10 
 Bottom view of the ferrule package, the round barrels are not used. The ferrules are available in different internal diameters, so it is posible to build a lighter antenna for QRP, with #18 copper wire and a center insulator made with 1/2" PVC material and a BNC connector,  instead of 1" PVC material and a SO-239 connector. Also if larger diameter wire is needed, like #10 for example, a larger ferrule can be used to complete the antenna construction in the same way as with smaller diameter wire.

Step 11 
 A close up view of the aluminum ferrules. If bare copper wire is used for the antenna construction, like # 14 copper-weld, do not use the aluminum ferrules. Solder the wires from the center insulator directly to the dipole antenna wires with good quality 60/40 rosin core solder and protect the connection point with liquid tape or silicone sealant. If the ferrule is used with bare copper wire, a chemical reaction will take place between the dissimilar metals, destroying the connection in little time. Do not use any type of crimping terminal to make the connections, as the connection will deteriorate rapidly and a resistance will be created at the connection affecting your antenna performance.

Step 12
 This is how the center insulator looks with both dipole wires already soldered to it. If you haven't already checked for continuity, it is now the time to do it , before applying the shrink tubing to the splice caps.

Step 13
 Now, the shrink tubing pieces are in place. Use a heat gun, hair blower or matches to shrink the tubing. Be careful not to melt the wire insulation.

Step 14
 If a crimping tool is not available, use a large flat blade srewdriver to crimp the ferrules. Hit the ferrules with the screwdriver and a hammer along the center on both sides, until the ferrule is completely holding both wires. Do not hit to hard or you will nick or break the ferrule.

Step 15
The completed half wave dipole antenna. This one in particular is cut for the 15 meter band. Between twelve or thirteen feet of cable are used on each side of the antenna. Remember, do not crimp the ferrules at the end of the dipole until you install the antenna and adjust both sides, adding or subtracting to the wire at the ends. Use an antenna analyzer or SWR meter to adjust the dipole to the desired center frequency. Remember, making the antenna longer , lowers the resonant frequency and making it shorter, increases the frequency. The dipole is a balanced antenna, both sides must be equal in length, if you add wire to one end, add the same amount to the other and vice versa. When the SWR is set to an acceptable level, lower the ends of the dipole and crimp the ferrules. Surrounding objects, the height above ground and the antenna configuration ,(inverted vee, sloper, horizontal, vertical, etc.) will influence the size of the wire elements on your particular installation. That is why it is advised to always use one to two feet of extra wire on each end to tune the antenna. Don't let a long piece of wire hang from the dipole antenna ends as it will add to the total lenght of the antenna and fool your adjustments. Wrap the excess wire over the antenna wire backwards, when you are satisfied with the tuning, crimp the ferrules and cut the extra wire on both ends. From the half wave antenna formula 468/F(MHz) remember the result is the total wire length of the antenna, divide the result by two and add one feet of wire to aid in the tuning process. That said, you will need two 10' sections on 10 meters, two 13' sections on 15 meters, two 18' sections on 20 meters, two 35' sections on 40 meters or two 70' sections on 80 meters to build a half wave dipole antenna for your band or bands of choice. If you have any comments or questions about the dipole antenna construction process or need technical help with your particular application, please contact me via e-mail. I hope this information helps other amateurs take the challenge and build their own good quality half wave dipole antenna, saving money and learning at the same time.

Sunday, July 8, 2012

Dipole Antenna Center Insulator Construction

step 1

The materials needed for the construction are, one 1" pvc cap, one 1" to 1/2 " pvc reducer adapter, one SO-239 chassis mount connector, four #6 sheet metal screws, three # 8 eye-bolts ,three flat washers, three split washers, six # 8 nuts and two pieces of # 14 gauge stranded copper wire, six  inches long each. I decided to use all stainless steel hardware for the construction, but zinc plated hardware can be utilized if desired. Remember that rust resistance is the advantage of using stainless steel versus zinc plated hardware. All material, except the SO-239 connector were purchased at a local Home Depot store.

step 2

Now you need to mark the location of the four  holes on the SO-239 to the 1/2 " side of the pvc reducer adapter and the top and side holes on the pvc cap. A 5/32 " drill bit is used for the three pvc cap holes and a 3/32 " drill bit for pvc reducer adapter holes. I used a drill press to make sure the bit stayed through the pvc material all the way, especially on the reducer adapter. If using a hand drill, care must be taken to ensure you drill all the way through the pvc reducer wall material. The depth of  four holes must be adjusted to a half inch.

step 3

This is how your cap and your reducer look after drilling. On the cap it is very important to center your drill bit on the top the best you can before drilling, a pilot hole can be made with a sharp nail to keep the bit from moving away. The side holes on the cap must be facing each other. Both holes are  1" above the open end of the pvc cap.

step 4

The correct sequence for the eye-bolt hardware assembly is shown. One of the nuts remains on the outside of the cap on all three eye-bolts  Inside the cap insert the flat washer first, then the split washer and the nut. Tighten the nut inside with a  long nose plyer, and then tighten the nut on the outside securely. 

step 4 b

This is the inside view of the pvc cap after all three eye-bolts are installed. Make sure the three nuts and the eye-bolt  threads do no touch inside the cap. I always keep the excess thread toward the outside of the cap. Sealing the cap up to the side eye-bolts with epoxy, silicone or hot glue is optional. If a 5/32 " drill bit is used you will notice that the eye-bolts make their own threads on the pvc material when installing them. In my opinion, sealing is not necessary.

step 5

Now it is time to solder the wires to the SO-239 connector. Before soldering it is a good idea to file around the center pin and along one side of the SO-239 close to the insulating material with a flat file to remove the nickel plating of the connector. This will help the soldering process. Remember , if using a 40 watt iron or soldering station, it will take several minutes for the exterior of the connector to heat up enough for the solder to flow. If you use a higher wattage soldering iron or soldering gun, care must be taken not to apply too much heat or you will end up melting the dielectric material of the connector. Always use good quality 60/40 rosin core solder and keep your soldering iron tip clean , never use acid type solder or paste flux on these connections

step 5 b

A side view of the SO-239 connector after both wires are soldered. It is a good idea to apply a little solder to the tips of both #14 gauge wires. Cut out about 3/8 " of the insulation on both wires, do not apply excess solder to the wire going on the center pin of the connector or it won't fit inside. Please allow enough time for the connector assembly to cool before continuing to the next step.

step 6

Using a hacksaw, cut the pvc reducer adapter, leaving 1/2 " of  the pvc material going into the cap.

step 7

Install the SO-239 connector using the four # 6 sheet metal screws. Tighten securely until the body of the connector sits flat against the pvc reducer adapter.

step 7 b

This is how the pvc reducer adapter looks from the inside after installing the SO-239 chassis mount connector. Sealing the connections up to the top of the reducer with epoxy, silicone sealant or hot glue is recommended. If hard epoxy is used, the center insulator can not be repaired in the future if needed. Replacing the wires or the SO-239 connector will require a new bottom assembly.( reducer adapter, SO-239 and wires)

step 8

In this step, drill two extra holes below the two side eye-bolts with a 1/8 " drill bit. Route the two copper wires outside the pvc cap ,as shown. Continue moving the bottom assembly upward while pulling the wires, each side at a time, until the reducer adapter is almost touching the pvc cap. Apply pvc cement and fully insert the adapter into the cap.  Pull both wires to make sure they are tight on the inside. Instead of using pvc cement it is also possible to use two # 6 sheet metal screws or rivets to secure the bottom part to the pvc cap. This makes it easier to make repairs on the center insulator in the future. (new wires, new SO-239,etc) Make sure if you decide to do this, that you drill the pvc reducer adapter perpendicular to the SO-239's sides, otherwise there is a chance of hitting the connector mounting screws.

step 9

The completed dipole center insulator after securing the bottom pvc reducer with the SO-239 connector to the cap. Using a VOM (volt ohm meter) or DMM (digital multimeter) check for continuity or shorts between the connector and the copper wires. In a future blog entry, I will show how to connect the antenna wires to the center insulator and to the end insulators completing the dipole antenna construction. There are many dipole antenna construction articles on the internet, magazines and antenna handbooks. This center insulator, especially if the stainless steel hardware is used, will provide many years of service near salt water. In my experience zinc plated hardware is cheaper, but won't last as long as stainless steel. Keep that in mind when deciding which one you will use in the construction of your outdoor antenna projects. If you have any questions about this project or any other antenna or amateur radio related matter, feel free to contact me via e-mail. I hope this antenna center insulator project help others decide between buying or building their own dipole antenna.