[Amps] More: corded dial drive help

Will Matney craxd1 at verizon.net
Mon Jan 23 15:53:49 EST 2006


Scott,

If there is a sprocket size difference, after you divide the large diameter by the small, the number of teeth on the sprockets have to end up equalling the ratio. In other words, if one sprocket diameter is say 1 inch and the other is two, you would have a 2:1 ratio. To match that with the sprockets say using a 12 tooth as the small, a 24 tooth would be used to make a 2:1 ratio. If both pulleys are the same diameter, you use both the same number of teeth sprockets. Timing belts and pulleys can be used this way too by the number of teeth on each pulley. Henry used sprockets though and are really tougher than what you have in there now. I think you'll find on one pulley that the hub has broke loose from the pulley somehow and is slipping. You might be able to fix that, I don't know. The pulley should not turn without the hub turning with it. Make sure the hub isn't turning on the switch shaft like a setscrew loose or something. The only reason there may be different diameters is that the switch sections rotate at different degrees between positions. If both switches rotate the same, then both pulleys will be the same.

Best,

Will


*********** REPLY SEPARATOR  ***********

On 1/23/06 at 2:11 PM Scott Townley wrote:

>good idea Will, thanks.  
>I've been waiting for a good excuse to order something from Small
>Parts...that place is a candy-store :-)
>
>> 
>> From: "Will Matney" <craxd1 at verizon.net>
>> Date: 2006/01/23 Mon PM 01:44:39 EST
>> To: amps at contesting.com
>> Subject: Re: [Amps] More:  corded dial drive help
>> 
>> Are the pulleys the same diameter on both shafts? If so, you could
>replace them with two minature sprockets and mini-chain. If they're
>different diameters, you divide the large by the small to get the ratio.
>Then two different sized sprockets can be figured by the number of teeth
>for each so the ratios match. Small Parts, Inc. down in Florida (I think
>they are) carry this very stuff. Any chain length slack can be taken up by
>mounting a small chain tensioner.
>> 
>> Best,
>> 
>> Will
>> 
>> *********** REPLY SEPARATOR  ***********
>> 
>> On 1/23/06 at 7:53 AM Scott Townley wrote:
>> 
>> >I am unfamiliar with these types of mechanics so it may take me awhile
>to
>> >give all the right info.
>> >The pulleys here use a plastic-covered metal cord (probably steel
>wire). 
>> >Each pulley has a gap on the periphery to permit the wires to route into
>> >the pulley area.  There are a pair of raised tabs (similar to clips) on
>> >the pulley surface that form a triangle with the gap.  On one pulley the
>> >wires are looped, crimped with a malleable and hooked onto these tabs,
>> >exiting the pulley via the peripheral gap and then wrapped around the
>> >periphery.  The 'far' pulley accepts the wire around its periphery, the
>> >wire enters the gap and hooks around the raised tabs in a continuous
>> >triangle.  In the end, the wire only makes one 'loop' around each pulley
>> >(there is no overlap).
>> >The pulleys appear to be held onto the shafts by what you could call a
>> >very short shaft coupler--a cylinder with setscrews but only about 1/4"
>> >long.
>> >What it all appears to me as is: (1) there is no means to adjust the
>cord
>> >tension, and (2) I can't figure out how the pulleys even turn the
>shafts. 
>> >The 'shaft coupler' is NOT unitary with the pulley...which I would have
>> >expected.  Maybe it's supposed to be, and mine is broken somehow?
>> >
>> >Later today I can put some pix of the specifics on the web for viewing. 
>> >Maybe the description will help, maybe not.
>> >thanks all,
>> >
>> >> 
>> >> From: Scott Townley <nx7u at arrl.net>
>> >> Date: 2006/01/22 Sun PM 11:59:56 EST
>> >> To: amps at contesting.com
>> >> Subject: [Amps] corded dial drive help
>> >> 
>> >> My project amp (specifically BTI LK-2000) has one of those
>ganged-corded 
>> >> dial drive mechanisms to turn the input and output band switches 
>> >> together.  Is there any reference mat'l that someone can point me to
>on
>> >how 
>> >> to maintain/adjust these types of things?  One is slipping and
>doesn't 
>> >> respond to my attempts at figuring out how it works (I can't see at
>all
>> >how 
>> >> it works, actually).
>> >> TIA,
>> >> 
>> >> 
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>> >> 
>> >
>> >Scott Townley NX7U
>> >Gilbert, AZ  DM43di
>> >
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>> 
>> 
>> 
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>
>Scott Townley NX7U
>Gilbert, AZ  DM43di





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