Good question. I was wondering the same thing.
Those switches have a serious detent.
Someone who has the resources could partially fill them in with a machine able
epoxy.
73 de Steve NR4M
Sent from my iPhone
> On Dec 25, 2020, at 3:47 PM, Jim <jimw7ry@gmail.com> wrote:
>
> Question Jim..
>
> Do you (would you) remove the detent from a Radio Switch band switch? Or will
> a large enough stepper turn them with the detent in place?
>
>
> Thanks
> 73
> Jim W7RY
>
>> On 12/19/2020 3:33 PM, Jim Garland wrote:
>> Hi all,
>>
>> As you probably know, commercial automatic vacuum tube amplifiers have
>> been available for more than decade, but they are expensive; their pricetag
>> adds about $2000 to the cost of a comparable manual-tuned amplifier. For
>> homebrewers, autotune capability is complex and difficult to duplicate, at
>> least for most of us who are not professional design engineers with access
>> to sophisticated workshops. For the past year, I've been working on an
>> autotune control circuit intended to overcome these barriers. The purpose is
>> to make it possible for amateurs with average technical skills to add
>> autotune capability to almost any vacuum tube linear amplifier, whether
>> homebrewed or commercial.
>> Here are the design goals for my controller:
>> (1) The performance should rival that of top-of-the-line commercial
>> autotune amplifiers, (My benchmark is the Alpha 9500.)
>> (2) The controller should be easy to duplicate for amplifier builders
>> with average homebrew experience.
>> (3) The controller should be affordable, costing no more than $100-$200.
>>
>> It has taken me a year to realize these objectives, most of which was spent
>> learning to use an advanced, yet inexpensive, microcontroller called the
>> Propeller PX32A. (The PX32A was designed in California by the Parallax
>> Corporation, maker of the popular Basic Stamp controllers) The PX32A is a
>> sophisticated device containing eight fully independent 32-bit
>> microprocessors that share 31 read/write IO ports and a common memory for
>> storing variables, computation results and data. These features make it
>> possible to construct a complete amplifier autotune circuit on an uncrowded
>> file card-sized printed circuit board using ordinary through-hole
>> components that can be wired up in an evening. The circuit board
>> intelligently operates inexpensive stepper motors and motorized switches to
>> adjust the tank circuits of almost any h.f. vacuum tube amplifier. An
>> ordinary PC or laptop computer programs the device, but once programmed, no
>> external computer is required. Because of its power, the PX32A implements
>> numerous advanced features while requiring only a handful of additional
>> components.
>>
>> Although it has taken me almost a year to write and debug the program code
>> for this controller, I 'm finally ready to move the project out of the
>> breadboard stage. Here's a link to a YouTube video that demonstrates the
>> controller's user features. (My eventual amplifier will use an 8877 triode
>> in a conventional grounded grid circuit, but that's a topic for another
>> day.) I apologize for the crudeness of the video, but hope you find it
>> interesting and will let me know your comments and suggestions. (If the
>> below link doesn't work, just Google "W8ZR YouTube Prototype Controller" )
>>
>> https://www.youtube.com/watch?v=1qDGoEElKcU
>>
>> Thanks and 73,
>> Jim W8ZR
>>
>>
>>
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>
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