[RTTY] TS570 with afsk

[Don Hill AA5AU]

Although I don't use AFSK for RTTY, I do use audio for PSK and have found some
distinction between different radios regarding ALC.  I use a resistive "pad" on
the audio input of the radio to reduce the audio from the sound card.  I also
reduce the audio output from the sound card using the sound card mixer settings.
Using the same "pad" and settings of the sound card provide different results
between my Kenwood TS-870 and Icom IC-756 PRO III.

With ALC reduced to zero the Kenwood only puts out about 25 watts, whereas the
same exact settings and using the same cable and "pad" produce a full 100 watts
output with zero ALC on the Icom.  As fact, I can turn the MIC GAIN all the way
up on the Icom with zero ALC and get 100 watts output.  I cannot do this on the
Kenwood despite the sound board setting being at its lowest level before being
completely muted.

This is another reason why I love this PRO III.

I use the MIC input for my audio input from the sound card on both radios.  The
Kenwood input from ACC 2 on pin 11 (PKD) is the same point, so it doesn't matter
where you input the audio because both places (MIC connector or ACC 2 pin 11)
are both mic inputs.  In the Icom, pin 4 of ACC 1 is a modulator input, but I
don't use this input and still get great results using the MIC input on the
Icom.

So maybe Kenwood just don't handle AFSK as well as Icom radios.  It would seem
that way.  The only real thing you can do is to experiment with different
resistive pads on the audio input of the TS-570 along with different settings of
the sound card output to eventually find a combination that will allow you to
have zero ALC with full 100 watts of output.  This appears to be more difficult
with Kenwood radios (I own 3 and they all react the same) than it does with
other radios.  Perhaps this is the reason I didn't like PSK to start with
because I always had to fiddle with the audio levels, whereas on my Icom this
doesn't happen (same would be true for AFSK RTTY).  Right now I love PSK,
especially since my last two digital countries confirmed (VU4 and VK0M) were on
PSK.  When you tune across 20 meters late at night and hear no signals on any of
the other modes (even CW), you'll almost always hear something on PSK.  It's
rather amazing really.  IMHO, there just isn't any substitute for FSK unless you
really know what you are doing.  K4GMH and W1ZT do extremely well using AFSK
RTTY and I believe they are both using Icom radios.

73, Don AA5AU



-----Original Message-----
From: rtty-bounces at contesting.com [mailto:rtty-bounces at contesting.com] On Behalf
Of Dick Kriss, AA5VU
Sent: Wednesday, April 27, 2005 11:44 AM
To: rtty-contesting
Subject: Re: [RTTY] TS570 with afsk

Peter,

I have been using a TS-570 in AFSK mode for both RTTY and PKS for some time and
it works great.

FYI, I show little (or no) power output on an external power meter sending a
stream of RTTY RYRYRYRYRY's (to dummy load) with the TS-570 Menu Option 33 set
to 0. This is normal as the zero Menu 33 option means OFF.  The power meter
shows about 25 watts with Menu 33 set to option "1" and full power 100 watts
with Menu 33 set to option "2" with "No" ALC action in either.

It sounds to me like they may have some sound card or software problems
generating clean audio to the TS-570.  Trashy audio input can show up as ALC.
Reducing the input drive level to the TS-570 will reduce the power out but does
not compensate for a trashy input signal.  They probably need to first clean up
(adjust) the audio output from the sound card before changing to FSK. 

Please have them contact me direct with more information on their setup and I
will try to help or refer them to someone on the TS-570 reflector with a similar
setup.  They should be able to reach full power with little or no ALC showing on
the S-Meter.

Dick, AA5VU


> Date: Wed, 27 Apr 2005 08:14:51 -0000
> From: "peter jackson" <peter.jackson17 at ntlworld.com>
> Subject: [RTTY] TS570 with afsk
> 
> Hi, two of our club members who are new to rtty find with their TS570 
> if they turn down the drive from the sound card so the ALC meter 
> dosen't read the power out is only about 10watts. Is this normal. Also 
> does the 570 support FSK? Hope someone can help, 73 Pete G3KNU


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