14 votes

How do PTT buttons work?

The basic PTT (push to talk) button on the HT is a simple switch that is normally open and when it is pressed, the switch is closed (conducting). Internally to the radio, this applies power to the PA (...
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  • 18.1k
9 votes
Accepted

Confusion about radio-computer interfaces: TNC, CAT, TRRS, Wolphi Link, ...?

First of all, don't feel to overwhelmed! This can be a bit confusing at the start, but once you understand the pattern and historical development, things will get a bit simpler. So fist of all, you'...
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  • 2,715
8 votes
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How do I put an RJ-45 connector on to repair a Kenwood MC-59 microphone cable?

Here's how to repair a Kenwood MC-59 microphone cable (ships with the TM-V71a, probably the 710, and a few LMR radios as well). First, if you didn’t know already, behind the rubber boot at the end of ...
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  • 1,615
8 votes

How much current can Baofeng UV-5R provide on +V pin?

With no load, I measure 3.17V With 100kΩ load, 2.91V With 10kΩ load, 1.59V With 1kΩ load, 0.29V The math works out to a 10kΩ series resistance between +V and ground. As such the maximum power that ...
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7 votes

How much current can Baofeng UV-5R provide on +V pin?

I would first measure the current draw of your ESP32 to rule out a fault there. The +V pin on the Baofeng microphone connection is probably intended to bias an electret microphone. These are ...
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6 votes

Is a connecting computer sound output equivalent to connecting a "dynamic" mic?

A dynamic microphone is basically a speaker in reverse. A diaphragm moves a magnet in proximity to a coil, varying the magnetic flux though the coil and inducing a current in it. You can in fact use a ...
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6 votes
Accepted

My radio and audio output keep changing using WSJTX on FT8

I'm not familiar with the failure modes of SignaLink devices, but in general, a USB device disappearing temporarily likely means that its internal microprocessor or USB interface chip has been reset, ...
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  • 22.9k
5 votes
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Using standard headphones with the Yaesu FT-60?

I've done some tests with what I have available (now including the CT-44 adapter). With the MH-37A4B Earpiece/Microphone connected, the internal microphone can still be used: whichever mic has its ...
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  • 22.9k
5 votes
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Mic ground vs ground

The problem you could run into is RF feedback into the sensitive mic input. This is particularly a problem if you run "QRO" - high power. It is best to use shielded multi-conductor cable, with the ...
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5 votes
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Iskra sst 2030 radio speaker plug

To me, this looks very much like a "DIN Lautsprecherstecker": Positive is the small hole, negative the wide slot. Loudspeaker, if I ask google, is zvočnik in Slovenian – so the "ZV" label makes ...
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5 votes
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Signal in the center frequency of my SDR spectrum always

That is DC offset, either in the analog to digital converters, or their driving circuitry. The average voltage at the ADC's input is ideally exactly in the middle of the ADC's range, since this ...
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4 votes

How to use HT microphone with two jacks (Kenwood connector) as a substitue for KX-3 microphone?

The Elecraft rigs have flexible interfaces for alternate microphone settings. However, there is only the single TRRS plug for a Microphone on the KX3. You should be able to wire up your own ...
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  • 2,868
3 votes

Iskra sst 2030 radio speaker plug

LEVI means LEFT DESNI means RIGHT ZV1 is speaker one ZV2 is speaker two S this radio has connections for two pairs of 4 ohm speakers. I guess LEFT ZV1 and RIGHT ZV1 are main speakers and ZV2 are ...
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3 votes
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Is packet radio possible on Baofeng UV-5R and similar HTs?

In the end I used 'amodem' ( see https://github.com/romanz/amodem ). After a few calibration steps, I could get decent I/O rates - considering the nature of the medium. Compression of archives is ...
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3 votes

Is packet radio possible on Baofeng UV-5R and similar HTs?

The easiest way now is to get the Btech APRS-K2 Cable: it allows you to receive and send audio to the radio with a single cable. You can use it with the aprs.fi app or with a variety of software from ...
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  • 141
3 votes
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How to hook up my computer's audio output to my CB Radio?

Most connector plugs make contact at 3 points: 1 Tip (pointy bit), 2 Sleeve (opposite the tip), and 3 Ring (between tip and sleeve). Depending on the rig, two of these will carry audio. One of the ...
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3 votes

What is the expected microphone input voltage level of a handheld transceiver?

A very simple adaptor can be built as follows: You can increase R1 to lower the signal level at the microphone output, or decrease R1 to raise the signal level. While some use potentiometers to make ...
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  • 11.9k
3 votes
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What is the expected microphone input voltage level of a handheld transceiver?

In general you are talking volts. But it's different for each make of radio and even different models of the same brand. You might want to start researching here, the link contains a vast amount of ...
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  • 6,264
3 votes
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How to use HT microphone with two jacks (Kenwood connector) as a substitue for KX-3 microphone?

In the end I decided to build a simple adapter. Most handheld microphones available at cheap prices have two-jack "Kenwood compatible" interface. They have 3.5mm TRS jack and 2.5mm TRS jack. The ...
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3 votes
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Looking for headset to use with BTech UV-25x2

There are standard connectors for microphones, speakers, and headsets, but unfortunately the pinout diagram (schematic) changes very frequently. There is no guarantee that a headset with a 3.5mm TRRS ...
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  • 8,922
3 votes
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Easy Digi hum with isolated ground

TLDR: 60 volts AC divided by the transformer CMRR is much greater than 1 mA times the resistance of the wire installed. -- In the first case - the raspberry Pi was floating at 60 V AC above ground, ...
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  • 7,817
2 votes

Kenwood TM-241A direct discriminator out

Typically a good place to get discriminator audio is the "high" end of the squelch control. Unfortunately the TM-241A does not have a conventional squelch control, making it necessary to tap onto ...
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  • 145
2 votes

Is packet radio possible on Baofeng UV-5R and similar HTs?

Sure it's possible. You'll need some sort of Terminal Node Controller (TNC), either one implemented in hardware or software, plus a set of cables that plug into the 2.5 mm / 3.5 mm TRS ports. If ...
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  • 8,922
2 votes

What issues can I expect when using Bluetooth for packet radio?

Sounds a lot easier to reverse-engineer the Hand Controller Interface, especially since that comes with a handy RJ45 connector, which would make it cheap to build an adapter that allows you to poke ...
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2 votes

Is packet radio possible on Baofeng UV-5R and similar HTs?

I was able to get a Baofeng HT working with packet, but had to adjust a number of menu items. (The tricky one that is poorly understood is Squelch Tail Elminate or STE.) My suggestion, assuming you'...
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2 votes

Is packet radio possible on Baofeng UV-5R and similar HTs?

I built a homebrew interface that uses a small USB soundcard with mic and ear 1/8" jacks. Each of those drives a 600:600 ohm transformer. On the radio side, the transformers drive the mic and ear ...
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2 votes

Is packet radio possible on Baofeng UV-5R and similar HTs?

I recommend against using the modern inexpensive HT radios for packet, especially if you are buying the equipment on purpose for that application. You'd be much better off with 30 year old used ham ...
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2 votes
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What cable is needed in order to record audio from a Baofeng UV-5x3 on a computer?

I built an audio interface that connected from an HF radio to my Mac, a few years ago. Obviously, I was concerned with ground loops and hum and suchlike, because I intended to use the interface to ...
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  • 4,291
2 votes

How should I measure RFI on the headset cable from a hand-talkie?

I doubt that SPICE modeling will be successful. There are required criterion that you do not have available such as the impedances at frequency of each device connection, the impedance characteristics ...
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  • 18.1k

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