[GreenKeys] Changing speeds on a Lorenz Lo-15b

[Duncan Brown]

I forgot to add - you can probably find a spot on the Range Finder that 
will copy fine for both 45 & 50 baud. Then you have an _automatic_, 
_adaptive_ machine that will copy both 45 & 50 baud with no speed 
selection needed!!

Duncan
K2OEQ

On 12-Dec-15 15:39, Duncan Brown wrote:
> Jeff,
>
> I'm sure you want the "challenge" doing this electronic speed control, 
> but have you ever tried running your Lorenz on 45 baud? Or a 45 baud 
> machine on 50 baud?  I have copied DDK off the air on a 60WPM TT-98 
> and copied 60WPM tapes on a 50 baud RFT T-63.
>
> These machines were designed long ago to work on long (many miles) 
> current loops with lots of inductance and capacitance distorting the 
> waveform.  Knowing that there would be lots of distortion on the 
> received signal, the selector mechanisms were designed to only use a 
> few milliseconds of the data pulse to make the mark/space decision. 
> They designed in the Range Finder adjustment to pick the best spot to 
> make the mark/space decision. The Range Finder determines the delay 
> after the start pulse to start reading the data pulses.
>
> When receiving a good RTTY signal (and especially when receiving from 
> ITTY, i-Telex, or Heavy Metal), you are starting with an almost 
> perfect digital waveform and then traveling over only a few feet of 
> wire to the TTY, so there is very little distortion. If you check your 
> Range, it will typically be 80-100 points. that is a lot to play 
> with.  If you set the Range low, the machine will start reading data 
> sooner and a 45 baud machine will be able to copy (slightly) faster 
> speeds like 50 baud. (The 1st bit is read early, the 3rd bit is read 
> in the middle and the 5th bit is read late.) Conversely, on a 50 baud 
> machine, set the range higher, and you will be able to copy the slower 
> 45 baud signal.
>
> You will not have as much range copying this "wrong" speed, but 
> generally you don't need much range with today's RTTY & Internet signals.
>
> Have fun,
>
> Duncan
> K2OEQ
>
>
> On 12-Dec-15 13:43, Jeffrey D Angus wrote:
>> I've been discussing various methods of dealing with setting the speed
>> on a Lorenz Lo-15b with Henning and Heinz.
>> It's a governed motor and will it's simple to just fiddle with the two
>> levers on the governor, it's not exactly a quick back and forth change.
>>
>> Now, Henning's pretty well got me sold on getting the i-Telex stuff and
>> connecting the Lorenz to that. No problem. That runs at 50 Baud.
>> But I also want to play with my HAL ST-8000A terminal unit and RTTY
>> via Amateur radio. Yuppers, _they_ all run 45.45 Baud.
>>
>> Now one truly novel approach, Henning sent me a picture of where
>> some clever person added a SECOND centrifugal governor switch to
>> the back of the motor. Just flip a switch to select either one.
>>
>> I've decided on something a little more "electronic" method. A phase
>> locked loop. Also, it's basically a going to be a "drop in" 
>> modification.
>> Something anyone with a Lorenz machine can just wire in, in place of
>> the centrifugal switch on the motor.
>> I've ordered a bunch of bits and pieces to play with.
>> Should have something up and running by the end of January.
>> "Film at eleven" as they say.
>>
>> Jeff
>>
>


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus