[CQ-Contest] Rise time

[Jukka Klemola]

Mike,
IC radios may have a fall time setting in addition to rise time.
I have helped a few people fix their fall time after sorting their radio's
rise time.

The 'off channel' energy, i.e.clicks, are created at moments where signal
changes.
In CW, there is just one power level and zero.

The change - going up or going down - creates the same emission spectrum if
the waveforms are identical.


To establish the knowledge for the milliseconds:

You have two radios.
You can listen to one radio transmitting on the other radio - keep the
antenna disconnected or have a short piece of wire as antenna for the other
radio that you use as the test receiver.
Transmitter of course outputs to a real antenna or a dummy load.

Send CW on the transmitting radio and S&P for the click phenomena on the
no-antenna receiving radio.

Adjusting to longer than 3ms is likely what you realize very quickly.
3ms corresponds to about 300Hz bandwidth.
Kind of too much, I would think.


About amplifier keying and avoiding hot switching, I use N1MM setting to
fire up the relays before any signal is transmitted.
I do not recall the name of the setting, maybe someone on the list
remembers that.


73,
Jukka OH6LI


su 7. kesäk. 2020 klo 0.27 Mike Smith VE9AA (ve9aa at nbnet.nb.ca) kirjoitti:

> All this talk about rise time, I didn't even recall that my (Icom) rigs had
> an adjustable one, or what it was for (until I read this thread)
>
>
>
> In my manual it gives me 4 options. 2, 4, 6 & 8 millseconds. (the default
> is
> 4ms according to my IC-7410 manual, though Icom warns that ( I quote) "If
> the rise time of a CW waveform is too short, key clicks on nearby
> frequencies can be generated"
>
>
>
> One rig was set to 6ms and one to 8ms.(why exactly, I have no idea-one rig
> is used and the other, while new,  has been away once for repair of
> something unrelated to keying)
>
> What would be the consequences of me setting them both to, say, 8 ms?
>
>
>
> Will amps key differently?  Will my CW sound soft? Will leading dits be
> clipped?
>
>
>
> Tnx for any info!
>
>
>
> Keep it clean, folks
>
>
>
> Mike VE9AA
>
>
>
> Mike, Coreen & Corey
>
> Keswick Ridge, NB
>
>
>
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