[GreenKeys] 404 OPM Speed for TT-4/TG

[Dale Hughes]

Folk,

Many thanks for your various suggestions for modifying the TT4 governor and
I will consider that option if gears aren't available.
I would be concerned about damaging the device though...

Regards

Dale


On Mon, 9 Mar 2026 at 15:40, Brenda Gentry via GreenKeys <
greenkeys at mailman.qth.net> wrote:

> Decades ago, I had a ready source of Kleinschmidt motors that were worn
> out or no longer met specifications and used them for experimenting and
> learning . Increasing the speed was easy to do with the adjustments
> provided, a notable increase was possible. If the increase is not enough,
> try using a piece of thin stainless steel wire to bind and collapse one
> turn of the governor spring. That will increase the spring tension and the
> speed setting. Don't use too much wire to bind the spring, it will cause
> unacceptable unbalance.
>
>
>
> B. Gentry, KA2IVY
>
>
>
>
> On 3/8/26 1:13 PM, Duncan Brown wrote:
>
> Pete,
>
> I will check our stock at the AWA (Antique Wireless Association - not to
> be confused with Amalgamated Wireless Australia) Museum when I am there on
> Tuesday.  I know I have extra gears, but don't know offhand if there are
> any 404 opm gears.
>
> All mechanical TTY machines can receive over a +/- 10% speed variation,
> using the Range Control to adjust when the selector magnet reads the data.
> So your TT-4 can copy 66wpm with the 368 opm gears (just turn the Range
> control down to about 20), but of course you will need the 404 opm gears to
> transmit 66 wpm.
>
> You could also try increasing the motor speed by about 10% while still
> using the 368 opm gears.  I don't know how increased speed would affect the
> life of the motor or brushes.  But since the unit was designed to work
> 24/7, and as long as you only use it a few hours a day, I wouldn't think it
> would affect its life significantly.
>
> Good luck & have fun,
>
> Duncan Brown, K2OEQ
> USASA    31J30
>
> Antique Wireless Association
>  Communication Technologies Museum
>    Asst. Curator, Commercial Equipment
> (also chief TTY op & repairman)
>
> i-Telex: 212503
>
> www.antiquewireless.org
>
> AWA Youtube channel:
> https://www.youtube.com/channel/UCX55peBhzeX1qps_VYXdLBA
>
> Virtual AWA Museum TTY Tour:  https://www.youtube.com/watch?v=TpB6jM90VV8
>
>
>
> On 3/8/2026 6:17 AM, Peter Leonard wrote:
>
> Hello all,
>
> I need a gearset for a TT-4/TG to operate at 404 OPM / 66WPM / 50 baud. I
> am happy to exchange a 368.1 OPM / 60 WPM / 45.45 baud set and a 600 OPM /
> 100 WPM set. The TT-4 manual states that the 368.1 OPM set is normally
> fitted and the 404 OPM set is held inside the machine. My machine is fitted
> with a 368.1 OPM set holds a 600 OPM set.
> I am located in Adelaide Australia and am happy to pay parcel post both
> ways.
>
> Kind regards,
>
> 73 Pete   VK5XP
>
>
>
> Peter Leonard
>
>
>
>
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