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

DTMF is an audio-frequency based signaling system that sends tone pairs as audible frequencies,. Most DTMF microphones send the tones as though they were ordinary microphone audio to be transmitted, so in the diagrams you have shown, the tones will use the same "MIC AUDIO" or "TX AUDIO" path as when you are talking into the mic. (And if you're interested in ...


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 ...


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

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

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).


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

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 have an IC 207H with a HM-133. The HM-133 came in a couple of flavors starting with the 133 then 133v HM-98s etc none of which replaced the HM-98 which came with the 207H. Dispite what ICOM factory service or the makers of the knock offs will tell you it just ain't the same. So get a real HM-98. Which will allow the 207H programming to work from the mic. ...


3

There's a great reference for radio and microphone pinout diagrams here: www.qsl.net/g4wpw/date.html. That site indicates that the IC-2800H is meant to work with the HM-98 rather than the HM-133, but the pinouts are the same, so if nothing else it will work as a microphone with a PTT button. The fancy buttons on the back are quite different, and who knows ...


2

As a general rule if the pins match it will work. They are usually a standard configuration. The real question is the quality.


2

The HM-98 uses a couple resistors for the up/down buttons, while the 133 uses digital signalling along with the rest of the keypad. It is MOSTLY compatible. For normal operation, it will work just fine. The only issue will be when it comes to putting the radio in programming mode. The HM-98 uses a couple resistors for up/down, while the 133 uses digital ...


1

I'm not sure exactly what you mean by "remote push to talk", but one possibility is that you want a switch that is more convenient, such as a foot switch. In that case you would want to get such a switch, and make sure that it's wired to be normally open, rather than normally closed. (Foot switches often have a micro switch inside with three contacts. ...


1

This answer has details that are not appropriately relevant because it does not match the actual features of the FTDX3000 microphone port. Update to come. I'm not familiar with the FTDX3000, but PC headset microphones, and most microphones for handheld radios, are both electret microphones. Electret microphones require a small DC voltage across their ...


1

Unfortunately your RT1 radio will not easily support VOX operation. The only control of the PTT is on the main radio or the remote. There is no push to talk (PTT) connection brought out on the radio or the remote. You could conceivably hack into either unit to bring out a PTT connection that could be interfaced to a VOX circuit but the radio does not bring ...


1

After a quick Google I wasn't able to find any devices on the commercial market but it doesn't sound too hard to DIY. Here's one: http://www.rason.org/Projects/basicvox/basicvox.htm Basically you amplify the audio, use it to charge a capacitor and then use the voltage across the capacitor to control a transistor which keys the transmitter.


1

An audio interface is a very different situation than a microphone, even though they both produce the same sort of signal at the same voltage. The microphone, specifically, must be protected. Assuming the microphone is of the electret type as is typical, the microphone has an internal amplifier circuit. This amplifier has to pick up the very weak signals ...


1

Consider a DPDT switch, extremely common . Open the mic on receive. The radio likely mutes mic audio when squelch closed. When you get a keypress beep or open squelch, it's probably enough audio to cover up the feedback you hear with a quiet carrier.


1

Usually this happens when you accidentally bend the inside of the jack (inside the radio) with the programming cable (or speaker mic) plug. In general you have to carefully open the radio and bend the contacts back down. Miklor has some instructions on opening the radio. There are also some videos of opening the radio on YouTube.


1

I'm looking at the Service Manual for the TK-805D and it shows +13.8 Vdc on pin 1 and +5 Vdc on pin 6. Mind you, these readings are hand written by whom ever posted this manual. Do you have the part number off the back of the microphone? I know this is a 3 year old post and hopefully you ere able to get your answer. I love this little radio, just don't ...


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