Annoying "Click" during RX/TX switch how to get rid of that?

[sp5it]

Hello.
I have President Jack. When I'm pushing PTT, every time is annoying, loud "click" in the speaker. Switching from TX to RX is quiet and soft. It is not the matter of the mic that I'm using.
Here are the schematics. Can anyone tell me how to get rid of that clicking noise?


Mike

 

[loosecannon]

i know you said that its not a matter of the mic you are using, but i still have to ask, does it happen with every mic you try in the radio?

the reason i ask is because this problem often happens due to the contacts in the mic.

if the contacts that make the TX connection touch before the contacts that break the RX connection open; then you will get a pop from the speaker.

D104's are notorious for this.

of course there are other reasons this can happen, but this is the most common and the easiest to fix.
LC

 

[357]

What mike?
It may be releasing keying the audio mic while the rx is still on for a split second.

I had a turner doing that and had to tweak the relays.

 

[sp5it]

I put relay that is swithing tx/rx. Microphone now is controlling only this relay. When I provide voltage to that relay via microphone or just piece of wire I can still can hear loud "click" when radio key up.
It is microphone independent.
Mike

 

[loosecannon]

im going to say that it is that relay that is your problem.

RX is not disconnected at the time TX is connected.

you need a "break before make" type of configuration.

this is from wikipedia:
Since relays are switches, the terminology applied to switches is also applied to relays. A relay will switch one or more poles, each of whose contacts can be thrown by energizing the coil in one of three ways:

* Normally-open (NO) contacts connect the circuit when the relay is activated; the circuit is disconnected when the relay is inactive. It is also called a Form A contact or "make" contact.
* Normally-closed (NC) contacts disconnect the circuit when the relay is activated; the circuit is connected when the relay is inactive. It is also called a Form B contact or "break" contact.
* Change-over (CO), or double-throw (DT), contacts control two circuits: one normally-open contact and one normally-closed contact with a common terminal. It is also called a Form C contact or "transfer" contact ("break before make"). If this type of contact utilizes a "make before break" functionality, then it is called a Form D contact.


good luck with it,
LC

 

[sp5it]

This relay is workind as you see on the pic. There is no way to hold RX when TX is switched.
Without relay was no diffrence, as I wrote before. I think the problem is when 8V TX is applied, in some place in circuuit this "click" is generated.
MIke

 

[loosecannon]

well, the relay was my guess.
maybe someone else will take a shot at it.
good luck with it,
LC