[Ham-Mac] TS-570S, SL-1+ Imac and cocoaModem 2.0 Digital Tune-Up

[Richard Kriss]

I just got around to adjusting the digital interface settings for the new
Apple 20" iMac 2.4 GHz Intel powered computer.  The new computer worked with
the old settings; however, I could tell it was time for an SL-1+ cover
removed digital tune-up.  Users with the new Tigertronics SignaLink SL-1 USB
interface do not have to deal with the cover removal issue.  It has external
controls.

First,  I set the Kenwood TS-570S AF-Input menu item #33 to option 1.  The
TS-570 has three audio input options: 0 for OFF, level 1 or level 2.  I
picked the level 1 so I would have the option later to bump it up, if
needed.  I then set the AF-Output menu item 34 to option 5 that is mid way
between 1 and 9 so I would have adjustment options later, if needed.

I then centered the two pots in the the SL-1+ and fired up the Mac OSX
coocaModem software's RTTY configuration panel and started messing with the
Rx  audio pot in the SL-1.  I was trying to detect as much signal as
possible without over driving the input to the iMac's audio Line-in input
using the Rx pot in the SL-1.  Yes, it sounds weird but Rx input to the SL-1
is audio from the rig and its output is input to the computer.  It took some
playing around to find the sweet spot that put the peak signals near the top
of the Config panel and the noise floor (for lack of a better term) close to
3/4 way up on the horizontal bars (2nd line down from the top).  I double
checked it in PSK mode as well.

Then change to adjust the output or transmit using the output slider in
cocoaModem and the pot in the SL-1.  I was looking for the spot were I was
getting 100 watts output on an external Daiwa CN-101 SWR/Power meter  with
zero ALC showing on the TS-570's S-Meter.  You can really hear the
difference in TS-570's speaker as you mess with (tweak) the two controls.  I
wanted the optimum setting to be at about 75% scale on the cocoaModem slider
so I would have fine tuning adjustments later without having to pull the
cover on the SL-1+.

After finding the sweet spot and before replacing the cover on the SL-1+,  I
changed over to PSK31 mode and tried the new settings at 5, 10, 35, 50 and
100 watts to a dummy load and only had to do some minor tweaking to ditch
the ALC but show good power output.

The bottom line is the tune up was needed and I am now good-to-go with some
fine tuning range left over in the TS-570S and cocoaModem.

AA5VU Digital Interface <http://www.qsl.net/aa5vu/digital-IO-aa5vu.png>.

Yes, I did try again to use the iMic for receive and found it near useless.
I know the iMic (not iMac) is an A-to-D converter; however, it acts like an
attenuator when used between the SL-1+ and the iMac USB port.  The only
reason I use the iMac is for Transmit so I can maintain the standard iMac
system beeps and sound. If you plug anything into the headset output on the
back of the Mac, it mutes the internal sound system and I don't want to mess
with a Y-adapter and powered external speakers.

The tune up was fun and AC4BB came back to my call on the first transmission
on 14.072 in PSK31.

Thanks for reading this blurb.

73 Dick AA5VU