On 2019-04-08 4:31 PM, Bob McGraw K4TAX wrote:
> I don't find the input impedance of the SDR Play/RSP1 to be
> anywhere near 50 ohms. In fact it is much higher. Thus the result
> of using a simple BNC "T" does not load the signal of the main
> receiver.
However, since the K3 receiver is relatively close to 50 Ohms, it
*WILL* load the input of SDRs with high input impedance - to the
extent that the SDR *can* lose 10 dB or more of sensitivity. The
splitter works to protect the sensitivity of *BOTH* receivers -
if that were not the case why do you think Wayne bothered to include
a splitter in the design for the KRX3!
73,
... Joe, W4TV
On 2019-04-08 4:31 PM, Bob McGraw K4TAX wrote:
I agree with Joe in the procedure. As to using or the need for a
"splitter", I don't find the input impedance of the SDR Play/RSP1 to be
anywhere near 50 ohms. In fact it is much higher. Thus the result
of using a simple BNC "T" does not load the signal of the main
receiver. If your SDR receiver does present a 50 ohm input, then you
can expect to loose about 3 dB of received signal.
And correct, the SDR will be protected when one is transmitting.
73
Bob, K4TAX
On 4/8/2019 3:22 PM, Joe Subich, W4TV wrote:
The answer indicated connecting the SDR antenna to some connector in
the rear of the radio, and pressing some number of front panel keys
to route the signals from the antenna to the SDR...
Connect a splitter, input to the RX Ant Out jack, one output to the
RX ANT IN jack and the other output to the Antenna input of your SDR.
Press the RX ANT button to activate the RX ANTENNA Out/RX ANT IN path.
> Also, is the output from the K3 at zero or close to zero when
> transmitting? i.e. is it safe for the SDR?
Yes, the RX ANT Out/IN path is on the receive side of the T/R switch.
There is no RF (or only leakage) present in transmit.
73,
... Joe, W4TV
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