14
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 (power amplifier) stage of the transmitter, it idles the receiver, it switches the frequency synthesizer to generate the correct transmit frequency and a number ...
9
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're confusing connectors and cable purposes. Some cable types for certain purposes have common connectors, but in general, be sure to differentiate between the ...
8
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 the Kenwood MC-59 mic cable is a regular RJ-45 jack:
Step 0. If you want to avoid all this, the cord is part Kenwood E30-7543-18 at PacParts.com. (They also ...
7
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 essentially a capacitor, with sound pressure changing the spacing between the plates and thus the voltage. They contain a FET buffer since the capacitor could not drive ...
7
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 can be drawn is at 1.59V/10kΩ load, or 0.25mW max power. Short circuit current would be about 0.3mA.
6
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 speaker as a dynamic microphone, though the sound quality is quite colored.
A condenser microphone is a capacitor. (In some places and times, "condenser" is ...
5
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 sense; you can switch between speaker pair 1 and 2.
5
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 shield being used as the return for the PTT control. The mic output (signal and ground) are separately carried to the mic input connector, where the mic "ground" ...
4
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 PTT switch pressed will provide transmit audio and the other will not. Furthermore, the external microphone is open-circuit when its PTT is not pressed. Therefore,...
4
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 microphone to the diagram I have included here (extracted from the User Guide).
4
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 maximizes the maximum voltage swing up or down before clipping. The DC offset is the difference between the ADC's "middle" voltage and the average voltage ...
3
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 additional (as option).
Each speaker connector is DIN speaker connector with two contacts. Wide contact is speaker minus, circular contact is speaker plus pole.
...
3
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 necessary, and may be considered unethical. But the compression algorithms (e.g. 7zip, xz) are public, and anyone paying attention can read the data.
Rates of >=...
3
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 a computer.
3
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 adjustments easier, I've found they are a frustrating source of noise and failure in such circuits, and suggest that, if used, they should be used only to find ...
3
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 information about microphone pinouts and links to even more information. I know you mentioned you are hacking what's probably a cheap Chinese HT, but this ...
3
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, or the USB connection itself failed.
The obvious hypothesis, then, is that your transmitted RF power is itself causing the problem by interfering with the ...
3
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 sleeve on 2.5mm jack provides ground contact. PTT contact is on 3.5mm jack sleeve and microphone contact is on 3.5mm ring.
I bought two jack plugs, soldered the ...
3
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 plug that works with one radio will work with a radio from a different manufacturer, or even a different model radio of the same manufacturer. G4WPW's site ...
3
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, being powered by a two-pin USB adapter. The radio was earthed by its power supply, coax, etc. So the transformers have 60 volts across them, and even the ...
2
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 the board itself.
Pin 9 of IC1, an MC3372, is the output of the discriminator. If you can locate and solder to this pin it should give you the desired signal.
If ...
2
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 audio lines also goes to the Push To Talk switch, with the other side of that switch having the third wire. When you push the switch, you short those lines ...
2
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 you're using a hardware TNC then you'll need some sort of computer and a serial or USB cable between the computer and the TNC. I've used a different model HT to ...
2
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 connections via the 2.5 and 3.5mm jacks.
I also used a cheap USB to serial board to run an optoisolator to trigger the radio PTT. The reason for this is that if ...
2
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 radio mobile gear, with more power, more selective receiver, more predictable operation, easier UI, and less RF into your digital equipment, easier connections, ...
2
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 around. Pretty certain that carries raw analog audio on any 2 of the 8 wires :), as they actually sell a mic adapter cable (OPC-589)! (turns out somebody did the ...
2
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 transmit too, so I used audio transformers as well.
But the one thing I found that surprised me was that (as mentioned in comments by Kevin) the Mac has a ...
2
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 of the connecting cable, the skin depth and effectiveness of the shield, etc. As you have observed, you will also struggle measuring the common mode current at ...
2
I don't know of digital-mode software that has the capability to open a file, but that doesn't mean that it doesn't exist. However, there is a handy work-around to your problem: a virtual audio cable.
A "virtual audio cable" is a piece of software that registers itself with the operating system as being both an audio input device and an audio ...
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