[Elecraft] Rx-In/Out used for exteranl SDR Device

[Dean L]

Interesting.
How would you measure the impedance the sdr rx or even the K3, for that
matter adds to the circuit?
I often wondered this when tuning a bandpass filter, to work with a
receiver, using a return loss bridge, how can you be sure the rx is
50ohm...?

73
Dean



On Sun, Dec 5, 2021, 6:27 PM Michael Tope <W4EF at ca.rr.com> wrote:

> Yeah, unless the splitter is active, the isolation is only going to be
> as good as the source match (i.e. VSWR looking back toward the RF out
> port of the K3). The devil is always in the details.
>
> 73, Mike W4EF...........
>
> On 12/5/2021 1:48 PM, Jim Brown wrote:
> > On 12/5/2021 1:18 PM, Joe Subich, W4TV wrote:
> >> This only works 1) if the SDR impedance is consistently high from
> >> 100 KHz to 54 MHz and 2) the SDR has excess gain to compensate for
> >> the loading from the K3 receiver.
> >>
> >> However without a splitter, there is no protection for the K3 receiver
> >> against spurious signals generated by the SDR!
> >
> > YES! And that, along with the stub-aspect of the loop to an
> > unterminated load, are the reasons for using one of the MiniCircuits
> > hybrid splitters. Note, however, that they are passive devices, and
> > like all passive devices, depend on all ins and outs be properly
> > terminated to meet isolation specs.
> >
> > 73, Jim K9YC
>
>
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