[GreenKeys] Governed model 14 motor

Mon Feb 20 23:07:06 EST 2023

I lifted the cover on my Model 15 and it looks like the governed motor in my unit is 2100 rpm instead of the 1800 rpm motor mentioned in the TG-7-x manual (my 15 is a TG-7-B). My strobe wheel has 10 marks on it, which at 2100 rpm is 2.857 ms per mark. This divides evenly (4) into the period of the 87.6 Hz tuning fork. Seems like a 90 Hz fork should be used with a 1800 rpm motor along with 12 marks on the wheel vs the 87.6 Hz fork called out in the manual, so I’m missing something.

How many marks on your governer wheel?

Mike

> On Feb 20, 2023, at 6:28 PM, John W9DDD <w9ddd at tapr.org> wrote:
> 
> 
> It turned out to be  2100 RPM missing its governor assy. Which is why I thought it was synchronous.  It has a power cord attached, has me wondering what they used it for.  
> 
> Forgot to make the point most governed motors I've seen were 2100 which would definitely require a gear change.
> 
> I see your motor nameplate says 1800 RPM, so I wouldn't think different gears would be required.  But Teletype has been known to ignore logical choices.
> 
> I may have a spare synch motor.  Will check after Jeopardy.
> 
> John, W9DDD
> 
> 
>> On Feb 20, 2023, at 11:13 AM, Mike Douglas via GreenKeys <greenkeys at mailman.qth.net> wrote:
>> 
>> I used the keyboard approach originally and then bought the tuning fork because it was relatively inexpensive, and like you said, a very neat accessory for the Teletype. Also, the governed motor wreaked havoc with the scope and triggering - even on a separate outlet and power filter.
>> 
>> When adjusting with the keyboard, there is a very good chance the 1 and 0 bits are not perfectly symmetrical. Type an "R" or "Y" and measure from falling edge to falling edge (or rising to rising) and shoot for 44 ms (two 22ms bit times).
>> 
>> Mike
>> 
>> 
>> On Monday, February 20, 2023, 08:37:29 AM CST, Eric Moore <mooreericnyc at gmail.com> wrote:
>> 
>> 
>> Thank you John, I was told a synchronous motor would need a new gear set.
>> 
>> I am concerned about the rubber part, is there a manual for these motors I can follow? I need to open it up and make sure the rubber looks ok.
>> 
>> I am torn on a tac or a tuning fork... I am leaning toward a tuning fork since it is such a neat accompaniment to this artifact, and as someone smartly mentioned I can dial in motor speed with the keyboard and a scope.
>> 
>> -Eric
>> 
>> 
>> 
>> 
>> On Mon, Feb 20, 2023, 8:24 AM John Nagle <nagle at animats.com> wrote:
>> 
>>  > From: Eric Moore <mooreericnyc at gmail.com>
>>  > Subject: [GreenKeys] Governed model 14 motor
>> 
>>  > Hello, I have a model 14 KTR that I have been working on.
>>  > I am looking for information on the governed motor it uses, picture
>>  > attached.
>>  > I am told it used a tuning fork for adjustment? Does anyone have one of
>>  > these, or a set of instructions?
>>  >
>>  > Thank you for any help!
>> 
>> Here's the tuning fork:
>> 
>> 
>> https://www.ebay.com/itm/vintage-military-teletype-tuning-forks-Nanasi-JC-Deagan-Jerico-180vps-120vps/124333026125
>> 
>> The motor has a centrifugal governor
>> to maintain the speed at 1800 RPM. The tuning fork is
>> to help adjust the governor.
>> 
>> The idea is that you look at the striped wheel through
>> the slits in the tuning fork, and adjust the speed until
>> the slits are stationary. It's like using a strobe lamp.
>> 
>> The little lever next to the flywheel on the motor adjusts
>> the speed. It presses against a rubber wheel on the flywheel
>> which turns a screw to increase or decrease the speed of
>> the motor.
>> 
>> I think you want a 90 or 180 or 360 vps tuning fork to get 1800 RPM.
>> The motor's data plate says 1800 RPM. That's 30 revs/second,
>> so if there are 12 white bars, you'd want a 360Hz flash.
>> You can use a strobe lamp if you have one around. Goal is
>> to get the motor running at 1800 RPM.
>> 
>> There will be a lot of arcing and RF hash. The model 14
>> is from the 1920s, before the widespread use of radio.
>> Later models have some filtering, but the originals do not.
>> 
>> Most Teletype machines still in use have a synchronous motor running at
>> 1800 RPM, which makes everything simpler. Consider getting
>> a synchronous Teletype motor. It's an easy swap. These machines
>> are very modular.
>> 
>>                         John Nagle
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