Yes, they did and the Drake PTOs were relatively cheap in the ¡®70s, now likewise on eBay. ?
I used them in my SolidState S-Line in the early 1970s and made my own calibrated dials attached to the PTO mechanism.
It was an overly grandiose project making an all band TX and RX with lots of xtals and new TO-5 RF relays.
They were about the same size as the S-Line (I still have them). Lots of double sided PCB material and 1/2 inch angle aluminum in those look alike cases. I post pics when they are back on the air.
?The uBitX is the solution! Followed by an RF2K+ this little rig should scream! Can¡¯t wait - mine should arrive Friday.
Dave WI6R
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On Dec 19, 2017, at 5:56 PM, K9HZ <
bill@...> wrote:
As a side note, all of the old drake 3 and 4 series (eg R4C) used transistorized PTO circuits which worked phenomenally well.?
Dr.?William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
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Owner - Operator
Big Signal Ranch ¨C K9ZC
Staunton, Illinois
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Owner ¨C Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it:
email:??bill@...
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On Dec 19, 2017, at 7:13 PM, Ken wa4mnt <
wa4mnt@...> wrote:
Analogs unite¡ This project started out about five or six years ago and was borne out of reviewing the Norcal 2030 assembly manual. I noticed the PTO (Permeability Tuned Oscillator) VFO was using a soda straw coil form and threaded brass rod as the tuning slug. I was uncomfortable with the idea of the tuning shaft having to move in and out through the front of the chassis as you tuned across the band. I have also seen this on a few other designs.
A year or two later I worked on a device that would keep the tuning knob stationary in relation to the front panel, (Z axis), and not have the threaded rod rotate at all, only moving it in and out of the coil form. It worked well but the necessity of machined parts, and overall size made it difficult for the average builder to embrace. Fast forward to recently, and building on the success of designing paddles for QRPGuys out of pcb material, I decided to re-visit the PTO project to see if I could reduce the dependence on machined components, reduce the size, and cost. The goal was to duplicate the action and performance of the original design, and use the fewest components.
After seeing one, Chuck Adams (K7QO) convinced me to offer it as a complete kit with all the mechanical components, and following the detailed instructions will allow builders to have a stable platform for their VFO projects using this technique. This is only the mechanical portion of a VFO. Chuck is pursuing accompanying circuit designs for various applications using this device. He and his contributors¡¯ adventures can be followed on his users group, /g/qrp-tech, and his website, .
The nylon coil form allows for an inductor with a usable winding of 3/4¡± long x 1/4¡± I.D.. Having 32 turns/inch thread on the threaded rod, translates to 24 turns of the tuning knob, varying the inductance in a linear fashion, if the full available coil length is used. There are provisions for a separate optional winding on top of the main winding if your experiments or design requires one. There are three mounting options, secured to a chassis front, mounted flush on a pcb, or mounted over a pcb with spacers to allow components to be mounted under the device.?Consult the assembly manual. The device has a small footprint of 3/4¡å wide x 3/4¡å high, and about 2 1/4¡å long. The assembly with knob weighs 30 grams.
For assembly details and ordering, visit .
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ken ¨C wa4mnt
