EH Scott Radio Enthusiasts

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AW-12 Deluxe AVC-- IF alignment and part question

After quite a while I'm getting back to the AW-12 and I'm hoping I can get some tips on the IF alignment.

Since I do not have any spare IF covers I'll need to drill a hole in at least one of the cans.  Before I tried to do that I wanted to see if anyone can provide advice on how to do that without damaging the can.

The other question is has anyone replaced the grommet where the cable goes into the back of the receiver?  The grommet has become very hard and is falling apart.  Any recommendations on what to use would be appreciated.  I'm considering just getting some various size grommets and picking the best fit just to prevent any damage to the cable.

Regards

Lars

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If you have good dial calibration on the Broadcast Band, and good performance overall, then maybe just settle for the somewhat higher oscillator circuit IF frequency.

As for the knobs, the 12 tube Deluxe (Deluxe for the new single dial tuning for 1932)  usually the "ship wheel" Walnut knobs.    Scott%20ship%20wheel%20knobs%201932-4.JPG

diameter:  small 7/8 ". tuning 1 1/8 "

Note there is a larger tuning knob at 1 1/4 "   

Note some have a smooth interior and some a pebbly interior.

I have seen  an early AW-12 with the same plain round style as on the earlier 2-Dial model.

I have found the ship wheel design at swap meets. 

The knob lady Julie McCall in Nashville is another likely source:  radiopup@bellsouth.net

David

Good information.

I'll look into Julie McCall because we are only about an hour south of Nashville.

I'm looking for more ideas on the problem with the alignment of the 1st IF.

The 2nd and 3rd IF transformers peak very nicely (sharp) but the 1st does not peak throughout the range of the trimmer.

The circuit of the transformers is pretty straightforward with a mica capacitor and the trimmer in parallel with the coil.

With the trimmer maximum capacitance the signal is a little better than at minimum capacitance but there is no peak in between minimum and maximum.

I temporarily tacked a 30 mmf capacitor in parallel with the the trimmer to see if additional capacitance would have any effect but that did not change the situation at all either at minimum, maximum capacitance of the trimmer or anywhere in between.

The coil shows continuity and just in case I resoldered connections but there has not been any improvement in being able to peak the 1st IF transformer.

I have substituted known good tubes and that has not helped either.

Any ideas will be appreciated.

Thanks

Lars

Have you checked the continuity of 1st IF coil?

And compare readings with the 2nd iF coil?

Carefully investigate the condition of the adjustment?

David

Thank you for your thoughts.

The continuity has been checked and the reading was ~ 2.4 ohms on my digital VOM.

This is the same reading that I get on the 2nd IF coil.

I have very slowly turned the trimmer on the 1st IF and if there is a peak it is very broad.

When I started working on this set I mentioned that all the IF trimmers were screwed down tight. 

With the exception of the 1st IF the other trimmers are now more near the middle of the range after alignment.

I also checked the shielded wires for shorts but did not find any problems there.

Lars

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