[Ham-Mac] Mod to SignaLink SL-1+ for USB Interface

[Chris Smolinski]

>Dick,
>
><< My problem with the iMic is due to some weird impedance mismatch unique to
>the TS-570.  >>
>
>I still contend you have some other problem. I run the iMic with my 
>TS570 with absolutely no problem with any mismatch. Both I/O 
>connections run perfectly. The output level from the 570 is set at 6 
>and the input level in the Sound control panel is set at the first 
>notch.  Output level from the Sound control panel is set at about 
>1/4 the way up and the input level on the 570 is set at 2. Perfect 
>copy, both ways, on PSK31 and MT63.
>
>Incidentally, I believe you keep quoting a 1.7 ohm impedence for the 
>iMIc but it is actually 1.7K ohms.

I ran tests with my iMic and found an even higher input impedance, 
the 1.7K ohm value may be a quoted "worst case" figure.  (Reference 
my email posting of 3/1/2005 where I gave my experimental results)

In any event, there is certainly no "impedance mismatch" issue 
involved here, since you are NOT trying to achieve maximum power 
transfer. The iMic is simply working as a voltage sensor, much like a 
volt meter. You don't have an "impedance mismatch" problem when 
you're trying to measure the voltage output of a power supply (with 
an output impedance of an ohm or less perhaps) with a voltmeter with 
a 10 mega-ohm input impedance.

There may be signal level issues at work here, but there are not 
impedance matching issues.

-- 

---
Chris Smolinski
Black Cat Systems
http://www.blackcatsystems.com