Thursday, June 25, 2009

Airband receiver...the saga

Yup....I think I broke an TDA1072 (AM demodulator et all). Trying to improve sensitivity on the airband receiver decided to try the NE602 as a front end... some soldering later (I never had tested the Si570 connected to the NE602) it was ready to rock....powering up and some hash sound (noise) changed "vfo" to the local FM station....and nothing...just before I notice the s-meter geting a litle higher than usual....normaly is a good sign, more IF, more signal... but nothing other than noise, time to check connections.... everything was alright except I forgot to solder one of the NE602 pins... soldered and nothing... some more tests and nothing.... you can imagine the rest... testing...soldering loop...
Ok the NE602 is not as easy as that, at least with the TDA IF, let's connect again with the TA7358.... now a circuit that was working is not any more and since the common part in the equation was the TDA1072 I assume it is broke or at least part of it... had no more patience for the day so I will leave it for further testing.

Anyhow, found a nice airband filter for a NE602 front end an probably will use part of it to connect the TA7358 maybe will improve things a little better.

Bought 2 MC3361 for making an FM IF, at least part of the airband schematic will be used if not for AM at least for FM.

Also going to make a small DC receiver, crystal controlled on 10.7Mhz so I can verify the 10.7 IF output, unfortunatly my scope is broken so other testing equipment has to be made to get more info.

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