[Elecraft] Elecraft Digest, Vol 91, Issue 25

[Larry Phipps]

On 11/17/2011 12:00 PM, elecraft-request at mailman.qth.net wrote:
> Date: Wed, 16 Nov 2011 12:14:37 -0600
> From: "Richard Fjeld"<rpfjeld at embarqmail.com>
> Subject: [Elecraft]  SDR-IF and I/Q questions
> To: "elecraft posting"<elecraft at mailman.qth.net>
> Message-ID:<4844C59175CE4F65BF4D7400354623EB at BIOSTAR>
> Content-Type: text/plain;	charset="Windows-1252"
>
> Larry,  (Reply to message 12, 16 Nov 2011)
>
> Yes, I have the XG2 generator for portable use, and another gen in a IFR1500 I can use.
>
> I wrote down the test levels when I tested the SoftRock w/Z10,000 but
> I don't remember them. I hope I can find the notes easily.
>
> I found this interesting: ("As the number of signals goes down,
> the required strength of the signals goes up")

As regards WBIR.

> I DO understand the last part of the paragraph,
> but I have a question about this: ("We use -50dBm (S9+23dB) in the
> shop to check out LP-PANs before shipping")
>
> What is the ratio of input to output level?  And better yet, what is the input level
> you expect  to see from the IF of a radio on average?  I'm curious.

I'm not sure which input and output you are referring to. The IF output 
of the K3 is about 7dB lower than the antenna input as I recall 
(assuming the rig has the buffer mod). The Z10000 can be set for less 
loss than that, so that the transfer loss could be reduced to zero. If 
you are using the KXV3 and Z10000, you could set the Z10000 gain to 
compensate, but it's still going to increase the noise floor. In the 
case of LP-PAN, we place a low noise preamp between the KXV3 output and 
buffer amp input (the LP-PAN buffer is similar to the Z10000). This 
allows lowering the noise floor while still having the high isolation 
advantage of the buffer. Jack offers a really low noise preamp that you 
could place between the KXV3 and Z10000 to accomplish a similar feat.

Pan signals should roughly match your K3 S-Meter if you calibrated the 
K3 against your XG2. I typically see signals at around S9 during the 
week, and maybe 20dB higher when the bands are open and crowded on weekends.

Larry N8LP




>
>
> Thanks again,
> Dick, n0ce