[Elecraft] SDRPlay connection to K3S

[Joe Subich, W4TV]

Doesn't matter if the SDR Play input is well above 50 Ohms.  What
matters is the *RELATIVE DIFFERENCE* between the SDR and the K3.
Unless both track closely the lower impedance device will "suck out"
signal from the higher impedance device.

In addition, one still needs isolation to prevent spurious signals
(e.g. Local oscillator, phase noise, harmonics etc.) generated in
one device from impacting the other.

73,

    ... Joe, W4TV


On 2018-07-17 1:08 PM, Bob McGraw K4TAX wrote:
> My measurements indicate the SDR Play input Z is well above 50 ohms and no degration  in signal strength was noted.
> 
> Bob, K4TAX
> 
> 
> Sent from my iPhone
> 
>> On Jul 17, 2018, at 9:16 AM, Joe Subich, W4TV <lists at subich.com> wrote:
>>
>>
>> You will need a (hybrid) splitter ... connect the common port of
>> the splitter to the RX ANT Out jack, connect one output of the
>> splitter to RX ANT IN and connect the other output of the splitter
>> to the SDRPlay antenna jack.
>>
>> A splitter is necessary to keep one receiver from loading the
>> other resulting in loss of sensitivity.  The receivers (K3, SDRPlay)
>> do not have identical input impedance across their range and one
>> receiver or the other can become (relatively) deaf on certain
>> frequencies depending on the characteristics of the input circuits.
>>
>> There are those who will say use a BNC T ... that may or may not
>> be satisfactory depending on cable lengths and receiver input
>> characteristics.  Unlike a hybrid splitter, the BNC T connector has
>> no isolation between output ports which allows spurious signals
>> generated in one receiver to be coupled directly into the other.
>>
>> 73,
>>
>>    ... Joe, W4TV
>>
>>
>>> On 2018-07-17 9:16 AM, Steve Muenich wrote:
>>> Hello gang,
>>> Is there a proper port on the K3S to connect a SDRPlay that would allow for sharing the main antenna while receiving, then be disconnected and isolated when the K3S go into transmit?
>>> Thanks
>>> Steve, NA5C
>>> K3S 10121
>>> Sent from my mobile device
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