[Elecraft] Mic and headphone

[Don Wilhelm]

The complexity may involve sorting out the headphone connection from the 
mic while keeping feedback away.  Telephone uses only a single pair wire 
in all installations I am familiar with.  Yes, there are 4 wires in the 
typical phone jack and cable, but that will handle 2 lines.

73,
Don W3FPR

On 3/4/2014 10:37 PM, N5AG wrote:
> Thanks Don.  I probably am worried about nothing.  I know some others using this setup on Kenwood and Flex.  Their's seemed a little more complex.  That is the reason for the question.
>
> Allen Griffith
>
>
>
> On Tuesday, March 4, 2014 7:33 PM, Don Wilhelm-4 [via Elecraft] <ml-node+s365791n7585134h19 at n2.nabble.com> wrote:
>   
> Allen,
>
> Most modern audio output stages are low impedance sources, and there is
> no need to "match impedances".
> Do you think about matching impedances when you plug something into a
> power mains wall receptacle?  Likely not, because the AC mains is a low
> impedance source and will deliver whatever the device needs. Your
> headphones are similar - with a low source impedance driver, you don't
> have to worry about it, just adjust the AF gain to a comfortable level.
> More power will be delivered to a low impedance device, but headphones
> do not require much power.
>
> The microphone is similar.  It is a relatively low impedance source, and
> it is operating into a relatively high impedance device (1k to 10k for
> modern transceivers) and the voltage produced is the important
> parameter.  Yes, high impedance microphones may not give the proper
> frequency response curve, but other than that, no impedance matching is
> normally required.  Modern microphones are in the range of 200 to 600
> ohms driving impedance.  I suspect yours is also in that range.
>
> 73,
> Don W3FPR
>
> On 3/4/2014 7:12 PM, N5AG wrote:
>
>> Has anyone wired up a Plantronics CS50 Telephone headset system to the K3?
>> The Plantronics CS50 system is composed of a base unit that transmits and
>> receives in full duplex to a small headset that is worn and gives the
>> capability to transmit and receive up to 300 feet.  The system uses 900 mhz
>> to communicate between the base and the headset.
>>
>> The base unit normally would plug in to a land line base telephone using the
>> standard four wire (two pair) found in most home telephone installs. I need
>> recommendations on wiring the Plantronics CS50 base unit to the back panel
>> mic and phone connections with the standard four wire line from the
>> Plantronics base.
>>
>> Does the K3 have the ability via menu selection to match impedances for the
>> mic and audio hook up stated above or must the matching be done in the
>> interface between the Plantronics base and the K3?
>>
>>
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