[Elecraft] K3 SoftRock 6.2 plus Z10000 buffer?

[Jack Smith]

Looking at the K3's filter plots, the center frequency is 8215 KHz, so 
the LO leakage is  be 23 KHz from the center. Even with the FM filter, 
this looks like adequate spacing.

A leakage signal at around -105 to -110 dBm 23 KHz offset would, I 
believe, not be a problem.

Unfortunately, my K3 won't be delivered for a month or two more (ordered 
in May 2007, but waiting on the second receiver to be sorted out) so I 
can't make measurements but the available data says it should be workable.

One caveat is is how close to the nominal crystal frequency the Softrock 
oscillator puts the actual frequency. The actual frequency depends on 
whether your 32.768 MHz crystal is cut for series or parallel resonance 
and the nominal load capacitance if parallel as well as the various 
components in the Softrock oscillator circuit. I don't recall at the 
moment whether the Softrock oscillator operates the crystal in parallel 
or series resonance.

Jack K8ZOA



Andrew Catanzaro wrote:
> Lyle and Jack,
>
> I have a Tony Parks SoftRock v6.2 Lite for 30 meters.  It's packaged 
> for use with the K3.  The included crystal is 32.7680 MHz and the 
> divide-by-four frequency is 8.192 MHz.  Combined with Jack's Z10000 
> buffer amp with 70 dB of isolation, is the local oscillator isolated 
> and offset from the K3's IF enough so that it won't degrade the 
> Elecraft's performance with IMD, BDR, etc.?
>
> Please respond to me on and off list as well as I receive only the 
> digest. Thanks.
>
> Andy W9NJY
> K3 #152
> -------------------------------------------------------------------
>
> Message: 19
> Date: Fri, 14 Mar 2008 11:00:26 -0400
> From: Jack Smith <jack.smith at cliftonlaboratories.com>
> Subject: [Elecraft] Second kit run - Z10000 buffer amplifier for IF
> pickoff K2 and Isolation (K3)
> To: elecraft at mailman.qth.net
> Message-ID: <47DA930A.4030605 at cliftonlaboratories.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> I've decided to go ahead with a second kit run of the Z10000 buffer
> amplifier. The Z10000 provides an isolated (70 dB isolation at 4.9 MHz)
> IF sample when installed in a  transceiver. It may also be used as an
> isolation amplifier with a transceiver with an IF output port. (General
> purpose, not limited to the K2.)
>
> The Z10000 will be available with several options, including one that
> permits it to be installed in the K2 and an electronics-only kit such as
> might be used with a K3, which has a built-in IF port. The Z10000 is not
> limited to the K2/K3 transceivers and has been used to provide a
> buffered IF sample with a variety of equipment employing IF frequencies
> in the range from 455 KHz to 73 MHz.
>
> The Z10000's primary purpose for K2/K3 owners is to use a Softrock as a
> panadapter via the Z10000 IF sample, and to provide additional isolation
> for the K3 IF output port. Note that even with 70 dB of isolation, it
> will almost certainly be necessary to offset the Softrock's frequency
> from the receiver's IF frequency to avoid interference.
>
> I've added pricing and options data at the 14 March 2008 entry at <
> URL:http://www.cliftonlaboratories.com/Updates.htm >. Availability is
> mid-April.
>
> I plan to order parts next week, and if you are interested in purchasing
> a Z10000, I would appreciate an E-mail indicating which options and
> quantities you are interested in.
>
> Jack K8ZOA
> www.cliftonlaboratories.com
>
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