unequal tone power output in FSK

[Mark n2qt]

This was a thread a while back, (the twist in the tones is induced by
passband ripple in the filters, worse with 5 poles) and there was a
possibility of a software update to flatten the tones.  I know it doesn't
really affect anything, but watching the LEDs on the W2 flutter just
doesn't seem right.

Mark n2qt

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[Dave Hachadorian]

Are you sure you are seeing unequal steady-state power on mark
and space?

What I see on both of my K3's are significant (+/- 7%) power
transients at the transition between mark and space.  These
transients show up vividly on an LED wattmeter, and I see the
screen current on a high-gain tetrode amp jumping like crazy.
I've complained about it on the reflector a couple of times, but
so far there has been no improvement.

The transients can be easily seen by hooking up a hand-key to the
FSK keying line and alternating between key-closed and key-open.
When the key closes, power momentarily spike upward.  When the
key opens, power momentarily spikes downward.  Steady-state power
is equal, key up and key down.

So far, nobody has complained about my signal, but amplitude
modulation can't be a good thing on FSK.


Dave Hachadorian, K6LL
Big Bear Lake, CA




-----Original Message-----
From: Mark n2qt
Sent: Thursday, August 25, 2011 2:41 PM
To: [hidden email]
Subject: [Elecraft] unequal tone power output in FSK

This was a thread a while back, (the twist in the tones is
induced by
passband ripple in the filters, worse with 5 poles) and there was
a
possibility of a software update to flatten the tones.  I know it
doesn't
really affect anything, but watching the LEDs on the W2 flutter
just
doesn't seem right.

Mark n2qt

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http://www.qsl.net/donate.html 

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[Richard Ferch]

I agree with Dave. If what you were seeing was due to passband ripple,
choosing a different RTTY pitch should make a difference. I don't
believe it does. Not only that, but if it were passband ripple, it would
affect AFSK A the same as FSK D.

My solution to this is to use AFSK A - it has almost all the same
features as FSK D, but produces cleaner output.

73,
Rich VE3KI


Dave K6LL wrote:

> Are you sure you are seeing unequal steady-state power on mark
> and space?
>
> What I see on both of my K3's are significant (+/- 7%) power
> transients at the transition between mark and space.

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[Jens Petersen-2]

On Fri, 26 Aug 2011 08:29:07 -0400, you wrote:

>I agree with Dave. If what you were seeing was due to passband ripple,
>choosing a different RTTY pitch should make a difference. I don't
>believe it does. Not only that, but if it were passband ripple, it would
>affect AFSK A the same as FSK D.
>
>My solution to this is to use AFSK A - it has almost all the same
>features as FSK D, but produces cleaner output.

I use DATA A at 1585Hz and have the same problem.
--
OV1A Jens

 Sent from my desktop PC with a nice big screen and a real keyboard.
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