Jaycar/SC Theremins - 2000 or 2009?

I'm looking at building a theremin, possibly from one of the Jaycar kits.  Once it's working, I'd like to build a wooden case and try some of the tone and linearising mods mentioned on the forum.  My electronics experience is mostly with building valve amps and guitar effects, so I can follow schematics and assemble things competently but don't know much about RF design.

I notice Jaycar have both the original 2000 model and the newer 2009 MKII kits available.  Which might be the better choice? 

Alternatively, I've seen some recommendations for the EPE 2008 design, and the PCBs are still available.  What's the availability of the coils like for these? 

The variable inductors of all Jaycar theremin designs are the same: This are standard 7mm IF filters with an integrated 150pF capacitor and a center frequency of 455kHz. You may use any variant, as long as you respect the color code (white for the 3 Hartley oscillators and black for the volume discriminator).

Jaycar is selling complete kits with all components, a PCB, all accessories like connectors etc. and even a small plastic housing included. I think it will be cheaper to buy the kit than gathering all parts together from different sources.

After reading a bit more, I decided to go with the EPE 2008 design, as it already includes the features I would otherwise want to add as mods (linearising coil, front panel tuning controls, waveform and symmetry controls etc).  I received the PCB this morning and the coils are winging their way to me from Jaycar.  The optoisolator and MC1496 are in stock at Farnell, so it looks like all the parts are still obtainable.  I have some pieces of cherry timber to build a case with, and I'll be sure to put up some pictures when I'm done.  This should be a fun project! 

Forget about this linearization coil. Since it has been added later to the initial coil-less design without modifying the oscillator's L/C ratio, it "linearizes" in an unpractical way, giving an octave spacing of only about 2.5" which makes about 1/5" per half tone. This close spacing does not allow precision playing.

Having simulated and played with this a bit on the bench, it seems to me that the term "linearizing coil" is something of a misnomer.  The operating point is largely determined by this coil and antenna capacitance, while the LC in the oscillator exists more to excite and sense the resonance point of the linearizing coil & antenna capacitance.

So you would suggest leaving it off, even on the EPE 2008 design where the coil is incorporated on to the PCB?  I had presumed that I would be best to build it as described in the article before making any changes. 

@Mart the Hat: A wire bridge will give better results in this circuit if you are a precision player. If you intend rather doing wooooooooo-eeeeeeee-oooooo sound effects, the compressed pitch field will help you a lot.

@dewster: It's somewhat more complicated than that. Finally, if you continue your research, you'll find out that the secret is one of the solutions of a at least 4th order polynome...

"It's somewhat more complicated than that. Finally, if you continue your research, you'll find out that the secret is one of the solutions of a at least 4th order polynome..."

Yes of course, with 4 complex impedances tied together one would expect 4th order response.  I'm just saying that, to a first order, the behavior of the linearizing coil dominates over the other components due to its large value.  And it primarily interacts with the antenna capacitance, which is generally small.  For different driver topologies the tank doesn't necessarily need to be designed to resonate at the same frequency (if the LC values of the tank are considered alone).  I'm not sure what this does to perceived linearity however. 

Thierry, can you accurately predict linearity?  If so, what is your approach and solution to this problem?

@Mart the Hat: A wire bridge will give better results in this circuit if you are a precision player. If you intend rather doing wooooooooo-eeeeeeee-oooooo sound effects, the compressed pitch field will help you a lot.

Thanks for the advice.  I will bear that in mind.  I do intend to use the theremin melodically, though I appreciate there will be a bit of a learning curve there!