Keppinger tube theremin builders, pt 2

Hi folks,
The old thread is closed so Im start up pt 2.
Its been a few months and Ive been been distracted on some other projects, but now the Kep is back on. I just finished winding all of the coils. Having made a proper winder (like to Mark's in his how to video) made it much faster and more pleasant than the previous large coils i've made, literally "wound by hand." Actually I found it a relatively enjoyable experience.
They turned out beautifully. Ill post some pics on my website soon. therealcharleshobbs.com (http://www.therealcharleshobbs.com)

I found some discrepancies between the listed winding lengths and what I got. Probably due to minor variations in enamel thickness between different spools. I stuck to the # of windings listed so Im sure its fine. (When I get around to it) Ill post the measured inductance of the different coils. Seems this info is nowhere on the web. Also difficult to find were the chassis dimensions... Thanks to a fellow over on the Keppinger yahoo group, I got some awesomely detailed drawings of the chassis. I guess i should ask first, but it would be nice to include them with the other info on the schematics page.

Chobbs on 5/27/10

"Besides the exclusion of R31 &32 are there any other changes to the revised parts list? i was just looking it over and that was all I noticed."

Sorry, but I was not able to respond since the topic was closed after your post.

I assume (and hope) you were aware of the correction made to the diameter of the the large coil forms by reading previous posts under that topic.

I was able to get the correction(s) posted to this site only a few days ago.

The coil total inductance is what you are aiming for. You can make up the difference with the C in the circuit. I highly recommend you do the concert modification, otherwise it will be bass tuned. There are a LOT of photos we've posted on our respective projects. If you were the gentleman asking for chassis drawings from me, I apologize for not responding. My family has had a rough time the past few months given the recent death of my father.

My fabrication page is at

http://www.neidlinger.us/keppinger.htm

Regards

Philip Neidlinger

JeffS -oh yeah. I didnt notice the coil diameters...I was just looking at components. Im using the tubes from red arrow hobbies, the item numbers are listed in the last thread. I belive that they are the same stock used by Mark.

Philip, sorry for your loss. No worries about the chassis dimensions, Im only getting around to building it now. I am well aquainted with your construction page. You did an amazing job on the theremin and the site. It is by far the best (and one of the only)collection of Keppinger pics and build info out there. Sometimes I stop by just to get motivated.

Here some info on the (my) coils. The part # refers to the phenolic tube available at Red Arrow Hobbies. (http://www.redarrowhobbies.com/phenolic_body_tubes.htm)

L1 Volume OSC
#RAHPT15 | 150 turns #28 |10.6uH (@50 turn-
tap), 53.5uH

L2 Volume Antenna
#RAHPT30 | 600 turns #32 | 12.75 mH

L4 & L5 Pitch OSC
#RAHPT21 | 150 turns #28 | 18uH (@50 turn-
tap), 92.8uH

L6 pitch Antenna
#RAHPT30 | 1200 turns #32 | 32.5 mH

Hey Philip, what did you use for L3? I couldnt find it in your chassis pics. I am imagining someting like the Miller 3-section RF chokes used in older Etherwaves and the EM theremin, right?

Pictures of my finished coils and winder can be found HERE (http://www.therealcharleshobbs.com/keppingertubetheremin)
Sorry for appearences. I just threw this page up, it needs more work and I plan to use it as a build log as the project progresses

Let me know what you think.

There are a few Keppinger chassis sets on ebay!

check it out! (http://cgi.ebay.com/Theremin-Chassis-Set-2-Keppinger-Tube-Theremin-/270588901485?cmd=ViewItem&pt=LH_DefaultDomain_0&hash=item3f005af86d)

A fellow theremin enthusiast hand made a few sets of 16 gauge steel chassis sets, prepunched and painted with "RCA brown" enamel. $65 for a pair is an incredible deal.

Yuck. Repaint them copper/bronze color to look like the old National Shortwave sets. Got my color from Autozone; a small can of touch up paint.

Brown is simply yucky.

Philip

I don't recall L3. I bought a whole lot of parts from someone at a bargain, which included most everything.

Philip