[TenTec] Omni VI & SignaLink USB

[Bob McGraw - K4TAX]

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 at contesting.com>
To: "Discussion of Ten-Tec Equipment" <tentec at 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 at 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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