[Milsurplus] [ARC5] 1625 and Key Clicks.
Bob kb8tq
kb8tq at n1k.org
Tue Jul 11 19:51:38 EDT 2017
Hi
> On Jul 11, 2017, at 7:42 PM, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
>
> On 11 Jul 2017 at 16:21, Bob kb8tq wrote:
>
>> Hi
>>
>> Time constant - how fast do you normally send?
>
> Around 30 WPM, most of the time. Sometimes a bit slower. There are a group of guys
> centered around 30 kHz up from the bottom of 40 and 20 who bang along at speeds up to
> 100 wpm. Some of their signals have very noticable clicks.
>
>> 10 WPM is 50 characters per minute or about one a second. With normal
>> spacing, you are at a character in a second.
>>
>> If you send a series of numbers, you have about 20 elements per second. Normal
>> letters will be a bit less.
>>
>> For reasonable "fidelity" you want a time constant / filter that will pass the 5th harmonic
>> of your keying "square wave". That gets you to about 100 Hz or so.
>>
>> This all scales with keying speed. If you normally send at 100 WPM, 100Hz becomes 1KHz.
>> None of it is exact. You could go to "3rd harmonic" and cut them 2:1. ...You could go to the
>> 9th harmonic and double the targets. It still works either way.
>>
>> Bob
>
> Thank you for that above, Bob. I'll file it in my file on keying methods.
No problem. I happen to be a fan of grid keying rather than cathode keying. It *does* take a separate bias
supply but it makes click filters much easier …
Have fun !!
Bob
KB8TQ
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