PAiA Kit - both antennas pitch only

Posted: 6/28/2005 3:38:12 PM
richapple

From: Santa Cruz, California, U.S.

Joined: 6/28/2005

Anybody have any experience with a problem upon completing the PAiA Theremax kit where the two antennas both only control pitch? In other words, the loop antenna doesn't do anything to volume but does also control pitch?
I just finished this kit and I made my own lectern case to specs (with the aluminum bottom and grounding to that).
Any advice appreciated...
Rich
Posted: 6/28/2005 4:42:09 PM
Jason

From: Sammamish, Washington

Joined: 2/13/2005

It sounds like you might have the fixed oscillators for each circuit tuned to a similar range. The circuit allows for some cross-talk between the two, so if you tune them to different ranges, you might elminate some of this problem.

Any other ideas?
Posted: 6/29/2005 10:47:46 AM
richapple

From: Santa Cruz, California, U.S.

Joined: 6/28/2005

Hmmm... I'll look into that. Thanks.
Posted: 7/13/2005 2:26:13 AM
Etherdave

Joined: 2/21/2005

I have never encountered this problem in 4 years of twiddling with the coils. Check to see that your coil cans are properly grounded. Make sure your volume control coil isn't tuned to a "false" peak as this may cause unpredictable problems. Lastly, check for shorts on your PC board.
Posted: 9/29/2005 12:26:14 AM
kkissinger

From: Kansas City, Mo.

Joined: 8/23/2005

The volume antenna affected the pitch depending on the setting on coil L4.

This procedure worked for me:

After tuning the pitch oscillators, before you remove VCA the jumper, go ahead and turn the adjustment on L4 and you may find a place where L4 interacts with the pitch oscillator. Adjust L4 to a position where the pitch is stable as you move your hand to and from the volume antenna. Then, remove the jumper and tune L3 to achieve your desired volume response.

Good luck!

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