Interfacing the UV5R with a Raspberry PI 3 Echolink-Svxlink

Posted on May 7, 2017
Filed Under Amateur Radio | 22 Comments

Today’s post is about my successfully interfacing a UV5R Baofeng with a Raspberry PI 3 running Svxlink.  Primary use is for an Echolink node connecting to a local repeater.
( Updated Jan3, 2018 – Some reports that not all variants of the UV5R work as described below. I have used the UV5R+ and UV5RV2+ successfully. )

My primary goal was to NOT use VOX to trigger the push to talk but to use a COS or Carrier Operated Switch.

Svxlink is a powerful software program that can be used as a repeater controller, a simplex link. Supports networked multiple receivers and transmitters. It also has an Echolink module.

Echolink is a popular system that allows two or more nodes to connect over the internet.

I wont discuss the installation or setup of Svxlink as that is covered many times. Svxlink has built in support of the GPIO (General Purpose Input Output) pins  on a Raspberry PI.

During my research time and time again I found reference to a hardware modification for the UV5R where you solder a wire to pin 2 of the audio amplifier in the UV5R.

The final audio amplifier’s supply voltage is removed when no signal is present and supplied when signals are received. This mod which connects to that supply Vcc was fairly easy and can be found here.

However I noticed on the schematic of the UV5R that there is no dc blocking capacitor on output to the speaker and external speaker jack.  The output goes to about 3 volts when the amplifier is enabled. To zero when no signal is received. Why then do I need to open the case?

UV5R audio output section

It is not necessary. Note the connection from pin 1 to the external speaker jack. Seems like a poor design to me to keep the internal speaker inline? (I wont go into the point of C158 and R192 in series with ground connect at each end? The schematic *must* be wrong..    At least their is 3 volts on the external speaker output when a signal is present…I can work with that!!

Here is the interface I built which works fine.  It expects the PTT control signal from the GPIO pin to go high (3v) to trigger the ptt output which grounds the PTT line from the UV5R.  And the COS signal to go hi (3v) from the RX when a signal is received. The output will also go hi when is connected to one of the GPIO pins on the Raspberry PI.

I decided to use 2 1:1 isolation transformers for the audio to minimize hum. I also am using two pc817 opto isolators instead of relays for outputs for the COS signal and PTT.

There are three adjustments. RX audio level, TX audio level and the COS/COR threshold. I made that variable so it can be used on other systems if desired.

Audio / digital interface for echolink for UV5R and Raspberry PI

Here is the first version of the circuit.

Completed interface board.

The main take-away here is NO NEED to MODIFY the UV5R.

This circuit can also be used to interface with a PC serial port *however* you might want to add a diode on the PTT input to prevent rs-232 negative voltages. And you don’t have to use 3.3v unless you are interfacing with logic that requires 3.3v.

I hope this helps some struggling Amateur. Feel free to use/modify etc to suit your purposes.

All parts were ordered on Amazon and the total cost is about $10. Hard to tell as I purchased the parts in lots of 10 or more.


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A Glimpse of Reality – Getting rid of the Electoral College

Posted on November 10, 2016
Filed Under America, Rants and Ramblings | Leave a Comment

Trumps successful bid for President has seemingly outraged many voters. Its not uncommon for the supporters of the losing side of an election to feel bitter. However there are yet again, renewed calls to do away with the Electoral College process used in the United States for Presidential elections.

Asserting  a “majority rules” method is more appropriate and represents the will of the people.

They are wrong for a number of reasons which I will eventually describe.

It is a shame. That these young people have no real concept of how and why we have the Electoral process in the first place and how it is an integral part of America’s founding principles. They should be careful what they wish for…. They wouldn’t like the result.

Surely they know that the process is an attempt to proportionally allow representation by the individual States. To keep a few high population areas of the country from dictating policy to a larger yet possibly less populated States.  Which basically means you have to take in account other areas wishes before a successful vote.

It is not often a problem.  Usually, but not always, the Electoral outcome matches the popular vote outcome.

Cries of fairness occur after a mismatch between the two happen.  Such as current events with protests over the 2016 election results.

If the U.S.A wants to have a majority rules election. Then it is no longer the U.S.A.  It becomes the “States with the most people” control all the others.  And that soon becomes “Taxation without Representation“.

When that happens, people end up dying.  *In large numbers.*
That is one of the MAJOR reasons the United States came into existence.

I’m not kidding here folks.

A simple majority method change would begin a shifting of our system toward a one government, one state; And that is a very bad idea. That is why it is in the Constitution, Article II and the 12th Amendment.  To change it you have to modify the constitution again and while your at it might as well change or remove the 10th Amendment.

Young people today (I feel) just don’t understand why things are done certain archaic ways. If they are taught history at all its skimmed over. Briefly.  They aren’t taught *why* some things occurred. Or they get fed information in college by liberal “professors” that feel the United States should change its government.

Population of US 2003

Population of US 2003

Thankfully amending the Constitution is difficult needing three quarters of the States to ratify the change. Not going to happen folks…

The small states (small in population) if they are smart are NOT going to let it happen. Basically if you look at this map, the areas in purple could control every election despite how the other states feel. That is no representation.

Well if they are smart the States wont let this be ratified.  You never know nowadays.


Perhaps the losers should have tried to convince more people their candidate was the best one.

Something to ponder…





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VOA Radiogram digital test broadcast 23 OCT 2016

Posted on October 22, 2016
Filed Under Amateur Radio | Leave a Comment

I received the test broadcast from VOA on 5745 khz. I have uploaded the audio file here. (30 mb). Right click to save it on your computer…

The broadcast starts about 1:30 seconds into the file. It is a .wav file and can be read directly by fldigi. (since it was made by fldigi).

It is encoded in mfsk 32.

Embedded were a few pictures see below.

I wont include the text here.

The audio file can be used to test your setup.


pic_2016-10-23_025736z pic_2016-10-23_025530z pic_2016-10-23_025140z pic_2016-10-23_024716z pic_2016-10-23_024102z

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Why Apple should NOT hack the iPhone for the FBI.

Posted on February 23, 2016
Filed Under America, Rants and Ramblings | Leave a Comment

cracked-phoneLaw enforcement would surely like the ability to be able to retrieve data from locked or encrypted cell phones of criminals.

Should Apple be forced to co-operate with the US Government and provide at a minimum the data from an encrypted / locked cell phone even if they don’t allow the FBI to crack the phone using methods they provide?

A reasonable person might say “Of Course” initially. Especially for terrorist charges. In this case a cell phone owned by the San Bernardino shooter.

Try to keep up. Lets discuss what this WILL lead to. Not what it might lead to, but where it must lead.

Apple creates new firmware allowing the phone to be accessed….because the court ordered it.  (But only for this particular case). The cell phone data is provided to the FBI. But not the software used to access the phone.

Precedent has been set. “Precedent or authority is a principle or rule established in a previous legal case that is either binding on or persuasive for a court or other tribunal when deciding subsequent cases with similar issues or facts.

FBI now says we have many cases, IMPORTANT cases… but we can’t access the cell phone data…. (Note that all these cases may not be terror related, some may be drug related, or perhaps a serial killer, but it is IMPORTANT!). Argues that this has been accomplished before, citing the previous Precedent.

A court orders a cell phone provider to provide the data on the cell phones…one at a time to Apple, Samsung or whomever manufactured the cell phones.  NOTE that these are no longer all Terror related incidents..but they are IMPORTANT!

You can see in our hypothetical world, that the courts are now ordering data for lesser things than Terror or murder? Drug rings? What if the I.R.S gets a court order?  We would have to rely on a judge to filter these requests to see if they warrant violating someones right to privacy. All judges aren’t the same some are less worried about privacy. Sooner or later the code used to access the phone will be leaked. Then no ones data using that phone / OS would be safe.

Some will say that if you have nothing to hide it should not be an issue.

Your right to privacy is a major issue! If you are arrested and have nothing to hide then provide the access yourself to the police.

You lock or encrypt your phone because you have personal information on the device. If its stolen, your data is still safe.

What about incidental information on a phone. What if, unrelated to your current charge, you  perhaps received a text from a friend that he scored some dope. Can the police then investigate your friend?

That may be simplistic but I can certainly see it happening. Once you start allowing access where does it end? Surely at first it will just be terror charges….but will end up for more minor charges and just fishing by the police looking for anything illegal. Perhaps just entering the border to return home from abroad…your phone will be accessed?

I am not saying I am against criminals being arrested. I am saying that I am against violating a persons privacy to achieve it.

The ends do no justify the means. Not in the long run.

There is one case where I am in favor of cracking a persons phone.  If it might contain actionable information to save a life in an emergent situation. Such as a child is kidnapped by a group and one of the group is captured but won’t talk. Their phone could contain timely information needed to rescue the child.  Many very rational sounding cases can be created for exceptions.

The line has to be drawn somewhere. My fear is it will be drawn such that ones privacy is to easily violated.

UPDATE: After posting this Gawker had this to say.

Another UPDATE: Court rules in NY that Apple does not have to co-operate.
“Orenstein concluded that Apple is not obligated to assist government investigators against its will .”

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Jackson County Amateur Radio Field Day 2014

Posted on July 3, 2014
Filed Under Amateur Radio, Gulf Coast | Leave a Comment

I recently joined the local Amateur Radio club and participated in their annual Field Day.
During this 24 hour period, groups and individuals demonstrate their ability to operate using in some cases emergency power such as generators or alternate energy sources. They build/assemble antennas in non standard locations away from their permanent locations.  They may coordinate with local EOC’s or authorities and demonstrate our ability to pass traffic/messages via non-standard but very reliable paths.

In our case we set up and operated out of the Emergency shelter facility in Vancleave, MS.  A great facility I might add.  I personally operated CW or morse code during my stint at the rig.  Was kind of rusty as I haven’t really operated CW in a long time. But it came back fast.  Had a great time even staying awake till the wee hours of the morning. I have been a licensed amateur radio operator since I was 14 years old…

I am happy that I am able to get back into a really fun hobby.

Visit the Jackson County Amateur Radio Assoc. site for information about the club.

Here are some pics of the setup and stations utilized. Had a great time and met some great hams. Be sure to see the cookies and items my wife made for the group and decorated them ‘ham style’.

If you want all the pics you can download them all in a zip file here. <- Thats for the club members that wanted copies of the photos…
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