[TenTec] Omni VI & SignaLink USB

[Bob McGraw - K4TAX]

Full FSK as I understand requires that the VFO frequency be shifted.  The 
Tigertronics SignaLink USB is an audio interface.  Perhaps the Bucscomm 
Rascal has a way of doing this or otherwise it is just a AFSK modem like 
majority of the rest.

73
Bob, K4TAX


----- Original Message ----- 
From: <qdot22 at gmail.com>
To: "Discussion of Ten-Tec Equipment" <tentec at contesting.com>
Sent: Thursday, July 10, 2014 4:40 PM
Subject: Re: [TenTec] Omni VI & SignaLink USB


> It's interesting that the Tigertronics unit does not support full FSK. 
> That's why I went with the cheaper Bucscomm Rascal.
>
> Rich, AA6VX
>
> Sent from my iPad
>
>> On Jul 10, 2014, at 2:15 PM, "Bob McGraw - K4TAX" <RMcGraw at Blomand.net> 
>> wrote:
>>
>> My reference to input and output impedances and to transformers on the 
>> input and output are from Tigertronics
>>
>> As provided with the SignaLink USB  data sheet.
>>
>> I  quote;
>> "Radio In/Out Z:    600 Ohm (nom).  TX/RX Levels are fully adjustable for
>>            compatibility with Hi-Z and Low-Z radio connections."
>>
>> From SignaLink USB data sheet I quote:
>> "Unlike some interfaces on the market, ALL SignaLink models COMPLETELY 
>> isolate your computer from your radio.  This eliminates troublesome 
>> ground loops and prevents hum and noise from degrading the signals.  The 
>> SignaLink USB provides isolation through the use of audio transformers 
>> and a relay-based PTT keying circuit."
>>
>>
>>
>> 73
>> Bob, K4TAX
>>
>>
>>
>>
>> ----- Original Message ----- From: "Jim Brown" 
>> <k9yc at audiosystemsgroup.com>
>> To: <tentec at contesting.com>
>> Sent: Thursday, July 10, 2014 12:18 PM
>> Subject: Re: [TenTec] Omni VI & SignaLink USB
>>
>>
>>>> On 7/10/2014 6:41 AM, Bob McGraw - K4TAX wrote:
>>>> Tigertronics i.e. SignaLink has transformers on the input and output 
>>>> signals for isolation.
>>>
>>> A transformer does NOT provide isolation to differential mode signals. 
>>> It only blocks common mode signals. For example, audio voltage on both 
>>> windings of a 1:1 transformer are equal, and no impedance is added to 
>>> the differential circuit. In a 4:1 transformer, the voltages are 
>>> proportional to the turns ratio, and the impedance looking into the 
>>> transformer is equal to terminating Z multiplied by the square of the 
>>> turns ratio.
>>>
>>> Remember that "600 ohms" has not been used in pro audio for at least 40 
>>> years. Output stages are low-Z sources, typically 100 ohms for pro 
>>> products, 300 ohms or more for consumer stuff, and input stages are high 
>>> impedance, typically 10K for pro products, 50K for consumer products. 
>>> The impedance of a microphone is defined as 1/5 of it's recommended 
>>> minimum load impedance, and a low-Z mic's output Z is typically on the 
>>> order of 100 ohms. All commonly used ham mics are low-Z, wired 
>>> unbalanced.
>>>
>>> As you have described the schematic, with individual 10K in series with 
>>> both the mic and line inputs, I agree there should be good isolation. 
>>> Perhaps the schematic is not accurate?
>>>
>>> 73, Jim K9YC
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>>
>>
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