model 42-322 alignment confusion - Printable Version
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model 42-322 alignment confusion - Guest - 06-11-2007
The instruction says set sig gen to 455kc, connect to antenna lug and set receiver to 540kc, tuning condenser closed (for the IF alignment). It fails to mention anything about what result should be (listen to speaker, read output on a my scope or VTVM), what sig gen mode (cw or mod and pct if reqd and level). Is the antenna lug the one screwed down to the chassis which is identified as external antenna or the loop antenna itself? It also says to set the volume to max! That would require ear plugs.
Dick
- Sean - 06-11-2007
The antenna lug on the tuning cap would be on the front section of the tuning capacitor. There will be a terminal where the antenna coil connects. That is where you should connect your signal generator. For the output indicator you can either connect a VTVM across the speaker coil, connect an oscilloscope across the speaker coil, or just listen to the audio through the speaker. Watch or listen for a peak in the output. Turn the volume control all the way up and use just enough signal from the generator to give a sufficient output from the radio to get the job done. The signal generator should be set for a modulated output.
model 42-322 alignment confusion - Guest - 06-11-2007
so I guess that means I must unsolder the wires from the loop antenna because there are strong stations all over which means the volume can only be turned up a small amount. I will have to deaden the receiver or the noise would shake the walls.
Dick
- rickd - 06-11-2007
Dick, Maybe just kill the oscillator. Jumper ground to one of the stationary plates.
model 42-322 alignment confusion - Guest - 06-12-2007
so I guess that would be the rear section since the front end section is already grounded. will give it a try if disconnecting the loop antenna does not give the results I need. thanks\Dick
- rickd - 06-12-2007
Dick, Guess I wasn't very clear. The tuning capacitor has two sections (front and rear). One for tuning the RF and one for tuning the oscillator. The usual arrangement is the stationary plates are connected to their respective circuit and the rotating plates are grounded. If the stationary plate section is also temporarily grounded it disables the function of that circuit. I don't know if the front section is the rf or osc. If that worked it would save disconnecting the antenna. Not a big deal but I'm lazy.
- Guest - 06-13-2007
in this model (42-322) the rotor is grounded as you say but in the RF section the stationary plates are also grounded through the antenna coil. I was able to do a great alignment of the bcst section by just removing the loop antenna. Of course someone had to tell me to modulate the sig gen which changes an almost impossible job to a much easier one plus connecting the sig gen to the correct point. In the SW section the alignment was a real bear. I had a terrible time adjusting the osc trimmer and finally found the right signal (not a harmonic) with the trimmer almost bottomed out (max C). This is a great little AA-5 plus 1 except for the hum problem caused by almost everything in the house that is plugged in. There is nothing I can do about that because all the caps have been replaced with new ones. Messing with the wire routing under the chassis might help but I have spent enough time with this project.
Thanks to all for the help.
Dick