[Ham-Mac] Sound Card

[Dick Kriss, AA5VU]

This is being RE-SENT again to correct my same old typo error on Kenwood
TS-570D(G) output.  The correct term is 4.7k ohm and I keep screwing up and
dropping the k.

On 3/3/05 7:03 AM, "Chris Smolinski" <csmolinski at blackcatsystems.com> wrote:

>> Duffey,
>> 
>> You may not have a problem. Check your TS-850 manual on the output impedance
>> on the 13-Pin ACC2 plug.  The problem seems to be unique to the 4.7 k ohm
>> TS-570 output. I look forward to your feedback and please document the
>> TS-850 impedance.
> 
> That seems somewhat surprising, as I have taken audio output from a
> variety of radios, with output impedances of 4 ohms (directly from a
> headphone jack), 600 ohms, as well as 10k ohms. The problem, if there
> is one, is not related to the output impedance.  A review of my
> previous email will explain why this is the case, as we are not
> trying to optimize power transfer.

Chris,

I read your previous message and understand your assessment that the iMac's
A/D is looking at the voltage in the input. I have no idea what voltage is
coming out of the TS-570 as it is not specified by Kenwood. The only
specification from Kenwood buried in table on page 15 of the TS-570 manual
is the Pin 3 ANO (from the ACC2 port) has an output impedance of 4.7k ohm
(note the correction!! to 4.7k ohm de aa5vu).

The problem I had was my Mac G4 1GHz AGP was near deaf to signals from the
ACCY2 port of the TS-570D(G) when interfaced via a Griffin iMic to the G4's
USB port.  The G4 hears very well when interfaced direct via the same cable
to the Line-in/Mic port to the Apple Built-in audio processor. My non
technical assessment is there must be some kind of mismatch between the
TS-570's output and what the iMic expects.  I liked W6FB's comment that it
acts like having a 200:1 SWR on an antenna.

The only other explanation may be the SignaLink SL-1 interface box could be
dropping the voltage from the TS-570's output as it changes the signal from
Mono to Stereo.  I did not consider the SL-1 as part of the problem because
I was using the same stereo cable from the SL-1 to interface to the iMic as
well as the Line-in port on the back of the G4. As a test I bypassed the
SL-1 using both a mono and stereo jumpers from the ext speaker port and had
the same results. For this reason I discounted the SL-1 as the cause.

FYI, the only reason I wanted to try the iMic was to see if the older
version Griffin iMic with the 20 bit A-to-D converter would improve weak
signal detection over the 16 bit sampling in the G4's Built-in audio
processor.  I have no real complaint with the Apple Built-in 16 bit audio
processor as I have worked over 165 counties on RTTY - many down in the
noise.  It was just an experiment.

BTW, I still use the iMic in my setup on the transmit side to be able to
maintain the G4's internal speaker for system beeps.  There is no mismatch
on the transmit side. The iMic works great on the transmit side.

73 de Dick, AA5VU