Correct Jack. Just a couple additional comments... LP-PAN has more than enough isolation, but we recommend the optional preamp (mounts inside LP-PAN) to overcome the total losses of the K3 buffer and the hybrid splitter in the P3.
FWIW, I have measured the isolation of the P3 splitter, and it is considerably lower than 30dB. If using a SoftRock, I would consider it imperative to use a Z10000 or similar buffer. It would also make sense to use one of your low noise preamps ahead of the Z10000 if weak signal decoding in CW Skimmer is important. I would set the gain of the preamp at about 10dB, and the buffer at about 0dB. 73, Larry N8LP On 8/29/2011 12:00 PM, elecraft-requ...@mailman.qth.net wrote: > Date: Sun, 28 Aug 2011 20:42:04 -0400 > From: Jack Smith<jack.sm...@cliftonlaboratories.com> > Subject: Re: [Elecraft] using P3 and Skimmer > To:elecraft@mailman.qth.net > Message-ID:<4e5ae05c.1020...@cliftonlaboratories.com> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > Don: > > I recently had a question from a prospective customer for a Z10000B > buffer amplifier about the need for additional isolation if a Softrock > is used with the P3's splitter IF output. > > I can't find a spec for the P3's isolation between the IF output port > and the IF Input, but 30 dB isn't a bad estimate for a 3 dB hybrid > splitter. > > Typical local oscillator leakage out of a Softrock is -40 dBm, so a -70 > dBm signal (approximately) will be injected into the P3's input if a > Softrock is connected to the P3's IF out port. This will appear as a > spurious pip on the P3's display at around -70 dBm. > > The LPPan has isolation and it's leakage is not a problem when used in > this fashion. But, I believe a Softrock will require additional > isolation, on the order of 60 dB or so, in order to be useful without > injecting a spurious pip into the P3. > > Jack K8ZOA > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
