Connect a Soundmodem with my CB radio? - Page 1
Forum section: electronics / rf-microwave

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 17, 2017, 02:19:58 pm
content: A friend of mine sold me an Soundmodem he dont need anymore: SCU-17Here is the Manual:http://www.yaesu.com/jp/manuals/ol/SCU-17_OM_ENG_JPN_EAK21X700.pdfI got some plugs from Ebay.How to wire it with my Radio?!Code:PIN 1 Microphone NFPIN 2 PTT-RX contact (on GND during reception) - also for NF uncoupling packet radioPIN 3 PTT-TX contact (on GND during transmission)PIN 4 UP/DOWN button (caution, special circuit for AE 5890 EU)PIN 5 Ground, shieldingPIN 6 Power supply for electrets microphone (or other accessories)And what kind of cable do i need for?!

author: Lord of nothing
author_rank: Super Contributor
timestamp: May 22, 2017, 11:16:25 pm
content: No idea?I never have tried connect a radio to an sound modem.

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 08, 2017, 07:03:05 am
content: Can someone help me to connect the CB Radio with the Soundmodem?I have no clue how it should work. What kind of Cable I need and how its stuck together.THX!

author: IanB
author_rank: Super Contributor
timestamp: July 08, 2017, 07:19:49 am
content: Quote from: Lord of nothing on July 08, 2017, 07:03:05 amYou have provided the manual in the first post. The unit is designed to connect a computer to a radio transceiver. After making the physical connection the computer will need to have suitable software to drive it. I do not know if this device is meant to work with a CB radio.The details of what kind of cables you need and how to connect things together are fully explained in the manual. If you have trouble understanding that level of technical detail then maybe you can try to find a local ham radio club to join where there may be people to help you?

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 08, 2017, 08:51:23 am
content: Quotethats no problem there are software who is used by ham radio operators to and dont require an radio amateur id. The Transfer Mode are the Same. Its PSK what is think.Quotehmm no...shield, unshielded, diameter,...?!Quotethere are just for radio amteursand the people are very selfish and think the know everything about RF stuff.Old People who like to sitt with a beer in there hand in a Bar and argue around who bad DMR, Tetra, Nextedeg is and how good Short Wave is for an emergency communication.QuoteI have 2 "friends" who are Radio Amateurs and the say just "hack it together".As an total noob I have NO idea how! I live just in an Apartment and have not that much tools or spare parts.That mean I have to order everything who I need.

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 26, 2017, 08:19:25 pm
content: Can someone help me what kind of cable do I need?

author: Lord of nothing
author_rank: Super Contributor
timestamp: August 18, 2017, 07:11:54 am
content: hmm?!

author: TheDane
author_rank: Regular Contributor
timestamp: August 24, 2017, 10:24:34 am
content: Quote from: Lord of nothing on July 08, 2017, 08:51:23 amFirst:It seems your plug pin out is missing audio output, hence your sound card isn't capable of decoding the received transmissions from the radio, when purely using the one plug you have described. You're most likely going to need another plug, and attenuate the output so the sound card isn't over modulated.I suggest to get the reception up and running before you start to transmit.Second: Beware of ground currents/loops. HF signals can destroy computers, if the energy flows in uncontrolled ways.You say you live in an apartment building. Do you get good reception on voice, using the frequencies you are allowed to use?If your radio reception and transmission quality is "deaf ear", it's going to be a no fun project I suppose.Another thing - public (free) Rx/Tx channel bandwidth is limited, usually 5-10-12.5 kHz, which leaves the baud rate very low. Packet radio on HF/VHF is usually 1200 baud (1.2k - verrrrry slooooooooow!!!!!!) so if you plan to get an internet feed through this way, it's going to be the slowest internet you have ever experiencedIf you can get your friends to help you (well teach you - real nerds love that thing), I would suggest to invite them over, and y'all have a nice 'hack-day'

author: Lord of nothing
author_rank: Super Contributor
timestamp: August 24, 2017, 10:54:09 am
content: HiI annoyed a German Speaking Forum until someone emplane to me what the information in the Radio Manual mean.In the Attachment is the wiring how it should work.Quotethats why a sound modem is used. The have isolated Ports to prevent it and the pc from over powering and current leaking.QuoteFirst I use CB. That is legal the whole EU maybe the Sound Modem Thinks to I dont know. Here in Austria its legal.I got someone on CB but nobody else. The problem quite nobody is use CB and some % of the freaks who use it use a Sound Modem.QuoteThats why I will get a Waterproofe CB Radio who have normal Audio Ports to use it for "Tracking". Over LTE I can controll/ send commands and see if I can receive it with my Handheltradio.Quote10khz on CB.Quotehaha I have an LTE Contract for Mobile use 5€ 1GB its enough.https://en.wikipedia.org/wiki/Olivia_MFSKhttps://de.wikipedia.org/wiki/ROS_(Betriebsart) (DE)https://en.wikipedia.org/wiki/List_of_amateur_radio_modes#Other_modes(ROS ENG)QuoteThe want to teach me how to make a Joint and Drink Beer.

author: TheDane
author_rank: Regular Contributor
timestamp: August 24, 2017, 12:46:02 pm
content: Understanding the scope/mission is sometimes what's needed to complete the journey- thanks for updating me a bit more.It sounds like a fun project, I remember when I was on packet a long time ago. It's a fun way to learn about RF and digital/analog signal transmission, if you have the dedication and/or people, clubs, forums, schools etc. to learn from.I do not know the specifics about the devices you're using, but usually PTT means 'Push To Talk'.From what I read from the picture provided (sorry, I haven't read through the datasheet you provided entirely - it's nice to see that it is galvanic separated on all I/Os but USB) the device is keying the receiver into either transmission mode, or reception mode.I could be wrong on this - but if I'm not, you won't get any RX data/audio on this pin. Pin 2 could be audio input into the modem, and if it is - and the modem shorts this to ground at (random?) times, make sure the radio output can handle a short.(Quote: PIN 2 PTT-RX contact (on GND during reception) - also for NF uncoupling packet radio )Tx data/sound should go into the microphone input, at the right drive levels/impedance, so not to over modulate the transmitted audio. Over modulation isn't useful - it creates all sorts of problemsElectret microphone inputs could require some hacking, as they can be DC biased. I suggest reading more:https://en.wikipedia.org/wiki/Electret_microphone

author: Lord of nothing
author_rank: Super Contributor
timestamp: August 24, 2017, 01:48:12 pm
content: Maybe someone can look over if something is wrong?QuoteI would say there isnt that much to learn. Maybe which freq is planed for what kind of transmission like Radio, Sea, Air,... In Denmark you should get Sea Traffic and that kind of stuff.QuoteNada just the Web who teach me the wrong side of Transmissions.QuoteCode:PIN 1 Microphone NFPIN 2 PTT-RX contact (on GND during reception) - also for NF uncoupling packet radioPIN 3 PTT-TX contact (on GND during transmission)PIN 4 UP/DOWN button (caution, special circuit for AE 5890 EU)PIN 5 Ground, shieldingPIN 6 Power supply for electrets microphone (or other accessories)The support was answer me:Quotethe quick and dirty translation mean on Pin2 is for "Loudspeaker". When Pin2 is put to Ground the Radio put there the Audio out. But how to put to Ground? Mean just connect with the Sound moden?!

author: TheDane
author_rank: Regular Contributor
timestamp: August 24, 2017, 05:39:07 pm
content: I have no idea about your radio, but the datasheet you linked to above gives a little info about the sound modem:Data Jack:PTT: Maximum output +25 V, 50 mA (open collector)FSK: Maximum output +25 V, 50 mA (open collector)DATA-IN: 100 mVrms @ 10 k OhmsDATA-OUT: 100 mVrms @ 600 OhmsFSK/PTT Jack:PTT: Maximum output +30 V, 250 mA (open drain)FSK: Maximum output +30 V, 250 mA (open drain)AUDIO Jack:AUDIO-IN: 100 mVrms @ 600 OhmsAUDIO-OUT: 100 mVrms @ 600 OhmsTo me it seems the sound modem 'shorts' the pin(s), and expects the radio to supply signals accordingly to the 3.5mm stereo jacks, or to transmit the signals sent.PTT/FSK input/outputs are opto-couplers/transistors according to the datasheet, and you can sink/source the current at max. voltage given above.The datasheets gives some info about changing mode between PTT and FSK, and signal attenuation - it's on page 13.(FSK is the modulation standard most commonly used on AX.25 packet - here's something to learn/read about:https://en.wikipedia.org/wiki/Frequency-shift_keying)- my not so native German translates the text into: When pin 2 is shorted, audio is 'transmitted' to you through a built in speaker.. Spreche sehr gute Deutch, aber ikke så længe af gangen :-)

author: Lord of nothing
author_rank: Super Contributor
timestamp: August 24, 2017, 05:54:41 pm
content: I will use just the Sound Based Mode like ROS, Olivia und PSK31.

author: TheDane
author_rank: Regular Contributor
timestamp: August 25, 2017, 06:20:36 am
content: How did my German-English translation fare, in regards to the speaker / pin 2- I presume you live around Wienerwald according to your tag line, and you said earlier you were on a German speaking forum - hence your German must be a lot better than my English

author: Lord of nothing
author_rank: Super Contributor
timestamp: August 26, 2017, 01:46:39 pm
content: So i connected the Radio with the Sound Modem and sadly to the lack of information i dont know if the Audio level are rite. The problem with SSB is when the Audio Level is to strong the signal is bad.

author: TheDane
author_rank: Regular Contributor
timestamp: August 26, 2017, 03:01:56 pm
content: If you add a potmeter in series with the audio signals (one for Rx and one for Tx), you should be able to attenuate the signals to the correct level quite easily.https://en.wikipedia.org/wiki/PotentiometerI suggest you read this blog, it explains how audio attenuation is done - though it is most likely overkill in your case to make a PCB and doing -1/-3dB steps.https://www.tubecad.com/2011/04/blog0204.htm

author: Lord of nothing
author_rank: Super Contributor
timestamp: August 27, 2017, 04:32:30 pm
content: the most annoying problem at the moment is the CB Radio inter-fear the Lan/ Fiber Media Converter.WTF...What is wrong with the Media Converter. Full Metal Case and just connect with the Switch and the Glas Fiber.