OK Bob: That indeed might be the case. I remember in the early days of packet
that I built up a little box that plugged into the mike jack and would switch
between
the mike and the TNC (MFJ didn't have that yet.). HI
Good luck on you effort there.
Clayton N4EV
On Thursday, July 10, 2014 9:47 AM, Bob McGraw - K4TAX <RMcGraw@Blomand.net>
wrote:
Oh yes I understand that. I have schematics and manual in front of me.
However they mike input and the audio rear connector are isolates by 10K
resistors on each one connected common to a summing point at the mike
amplifier input. With a low Z mike {500 ohms} and the SignaLink output
being transformer isolated, again low Z, there should be some 35 dB
isolation. This issue, there is no audio from the SignaLink as it appears
at the radio and when using the mike only white noise appears.
The project is some 5 hrs by car away. My concern is that the 10K resistors
were removed by a previous radio owner or were omitted during production. If
so, then indeed the two input are parallel.
73
Bob, K4TAX
----- Original Message -----
From: "Clayton Brantley via TenTec" <tentec@contesting.com>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Thursday, July 10, 2014 8:32 AM
Subject: Re: [TenTec] Omni VI & SignaLink USB
Bob: The Omni VI+ manual does caution you that both the mike and the rear
audio connector are in
parallel and infers that you should remove the mike when using the rear
panel audio input. The manual
does caution you that the mike is still active and using digital modes any
noise the mike hears is also
transmitted
This is not from the "horse's mouth" but just from my reading the manual.
On Thursday, July 10, 2014 8:45 AM, Bob McGraw - K4TAX <RMcGraw@Blomand.net>
wrote:
I'm trying to assist a friend setting up his Omni VI with a SignaLink USB.
He does have the cable supplied from SignaLink and it seems to be connected
to the radio correctly. It receives and decodes PSK-31 very satisfactorily
and it keys the transmitter correctly.
The difficulty is having both the SignaLink connected to the Audio IN on the
rear and the microphone connected to the front at the same time. The
SignaLink appears to key the radio correctly but does not produce output.
When he then later and on a different frequency tries to transmit SSB only
white noise is heard. If he unplugs the cable to/from the SignaLink the
noise is not heard. This occurs when the SignaLink is off or on.
It appears from the schematic the mike input on the front and the rear Audio
In are each isolated by a 10K series resistor to a summing point at the mike
amp input. Using a low impedance {500 ohm} dynamic mike and the SignaLink
output being some 600 ohms, I calculate the isolation between the two inputs
would be some 35 dB or so. Certainly this would seem to be very adequate
isolation such that having the two connected, although the SignaLink is off,
it would not interfere with the use of the mike. And with the SignaLink on
it would produce audio and it would not be interfered with the connected
mike.
Anyone have any specific experience or thoughts on this configuration?
73
Bob, K4TAX
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