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

[Jim McDonald]

Another option, which I've used, is to connect the SDR to the IF OUT, using the splitter in the P3, or directly to the IF OUT on the K3.

The available bandwidth is the 200 kHz (I think) at the IF, of course.  N1MM and DXLab have an option to specify the IF input instead of using the signal from the antenna.

Jim N7US


-----Original Message-----
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> On Behalf Of Joe Subich, W4TV
Sent: Sunday, December 5, 2021 15:19
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Rx-In/Out used for exteranl SDR Device


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!

73,

    ... Joe, W4TV


On 2021-12-05 1:35 PM, Bob McGraw wrote:
> I use a pair of BNC to BNC cables, about 4" long, from the RX OUT and 
> RX IN to a "T" connector.  The 3rd port of the "T" goes to the SDR.  I 
> find that the SDR input impedance, is nowhere close to 50 ohms,  is 
> high enough that it doesn't load the signal on the main RX.   Again, 
> no splitter required.   No loss encountered.
> 
> Yes, one does have to select RX ANT on the front panel for this to be 
> active.
> 
> 73
> 
> Bob, K4TAX
> 
> 
> On 12/5/2021 11:36 AM, elecraft-request at mailman.qth.net wrote:
>> Message: 22
>> Date: Sun, 5 Dec 2021 17:35:46 +0000
>> From: Dave<dave.g4aon at gmail.com>
>> To:elecraft at mailman.qth.net
>> Subject: Re: [Elecraft] Rx-In/Out used for exteranl SDR Device?
>> Message-ID:
>>     
>> <CABiKjG5c=s76xxwaxHJiiQYr+C3RtR_FYRHCb3YsN++=Xnn_=Q at mail.gmail.com>
>> Content-Type: text/plain; charset="UTF-8"
>>
>>> I see about a 3 S-unit drop in signal level when routing through the 
>>> splitter
>> Pete (N4ZR), what do you see with a straight cable linking in/out?
>>
>> I have no idea about Minicircuits splitters, but my home made one had 
>> a measured 3.1 dB loss at 29.7 MHz.
>>
>> 73 Dave G4AON