My connex 3300 wont transmit anymore and the talk back wont work either,i have tried a different mike and when you key it up the meter still won't swing.

Does the unit work when it is not hooked up to the linear? The obvious choice is that you have blown finals in the RF output section of the radio.

You need at least 8 amp power supply

May need some test equipment to find the fault on that one.
You could send it in to us and we can fix it.
*Just keep in mind that a new radio like that General Lee or Connex 3300 are only $199.99 MAX !!!+tax of course.. soo it depends on how much you have invested as if it is worth it to you to spend anything on it.
We do not charge to look at any radio -no bench fees-..
Let me know Ill get you any info that you need.

You may have a dead meter.
Modulation is audio's affect on swing wattage or pep. Notice that needle moving more with your voice.
Dead key or carrier wattage is without your voice enhancing the power only with mic keyed.
I can only assume that the chipset you are referring to is an ic chip audio or pll which must be working if you are receiving audio.
Check your mic cord................ transmit and modulation and even your receive volume can be affected by the cord/mic plug solder joints or broken wires here.
http://www.cbtricks.com/radios/galaxy/dx33hp2/graphics/dx_33hp2_sch.pdf this is a similar radio the General Lee, Connex 3300hp and Galaxy hp2 share boards i believe dont hold me to that thou.

check mic or coxail

in older connex 3300's you cannot disable the talk back. Its part of the audio chain. If you disable the talk back you will loose your audio. There are 2 things you can do.

Hook a relay to the speaker so that when the radio key's id disconnects the speaker. (Big pain, not worth the trouble.)

The other will not disable the talk back but it will stop any squealing.

Use a noise canceling mic. An RK-56 will work great. You will get no squealing with that mic.

There are problems with having a loud talk back. You can get feed back and an annoying squeal when you transmit. That is why the talk back isn't that loud to begin with.

The reason you use talk back is to check your echo, and make sure your mic gain is not too high. It shouldn't need to be that loud to check it.

I highly recommend you leave it at the level that it is.

check your mike / rf gain knob

The Connex radio is a division of Cobra, and no offense, but Cobras are one of the cheapest radios around. The problem with your Connex is a simple receiver malfunction. The receiver probably worked great until it was put into storage for a long time, you can replace the receiver, or you can fiddle around with the receive gain until you hear something. But you may just want to send it to a radio store and have it looked at, to be honest with you, Connex is a terrible radio, they sound good, but they're terrible radios. Go with Galaxy or Uniden radios, you won't be disappointed.

A word of advice, never buy a radio second hand. Used radios are sold for some odd reason, and it may be because it is broken. And yes you can do it with your meter, you just have to tune the radio using Coarse and Fine adjustments, also use peaking if you know how, to get a better transmit and receive.

Good luck!