[Elecraft] QEX article and K2

[Jack Smith]

Connecting a panadapter *after* the crystal filter would indeed be an 
exercise in futility.

The normal connection point is to the post-mixer amplifier ahead of the 
crystal filter via a high input impedance buffer amplifier, and thus the 
only selectivity of importance is that of the K2's input bandpass 
filters. The bandpass filter width depends upon the band selected, but 
in the worst case is several hundred KHz wide.

The Z90's widest built-in span is 200 KHz, and the widest permitted 
user-defined span is 250 KHz. These limits are set by the maximum filter 
bandwidth within the Z90 (1 KHz) and the number of data points taken 
when the data collection is set to maximum (240 data points).


Jack K8ZOA
www.cliftonlaboratories.com



Rob Locher W7GH wrote:
> Hi Jack,
>
> My budget unfortunately doesn't have any room for one of your 
> panadapters at the moment, but I'm curious anyway: how much bandwidth 
> do your panadapters show when connected to a K2?  Does the bandwidth 
> vary depending on which crystal filter is selected?
>
> 73,
> - Rob W7GH
>
>
>
>
> On Mon, 26 Mar 2007 16:43:23 -0700, Jack Smith 
> <jack.smith at cliftonlaboratories.com> wrote:
>
>> John:
>>
>> I am the author of the QEX article and the designer of the Z90 and 
>> Z91 digital panadapter.
>>
>> Although these were designed as a general purpose panadapter, it 
>> turns out that about 90% of my customers use it with a K2. 
>> Consequently, I have modified the computer display software to 
>> integrate with the K2 to permit mouse click tuning, i.e., click on 
>> the spectrum display with the mouse and you can automatically tune 
>> the K2 to that frequency. It's a pretty nifty feature and works 
>> reasonably well.
>>
>> The display height is 4.5 inches or so, and with the necessary 
>> clearances, one needs an enclosure that is about 5 inches tall, and 
>> preferably a hair taller.
>>
>> I have one customer  that installed (or he may still be in the 
>> process of building it) the Z90 in a home made enclosure that is a 
>> scaled up K2 enclosure.
>>
>> Jack K8ZOA
>> www.cliftonlaboratories.com
>>
>>
>>
>> John Wiener wrote:
>>> I remember reading on this reflector that the spectrographic display 
>>> design (Pan-something) in a recent QEX article was designed with the 
>>> K2 in mind.
>>> I was wondering whether anyone has considered this to be a worthy 
>>> occupant of an EC2 cabinet (the large one).
>>> Has anyone homebrewed this device?
>>>
>>> I think it comes as a kit but from what I recall from the article, 
>>> it seemed to be above my head as I am a pre-computer oldie/newbie or 
>>> whatever.
>>>
>>> Sure would give Icom a run for the money to have a K2 with a 
>>> spectrum display.
>>>
>>> Any thoughts?
>>>
>>> John
>>> AB8O
>>>
>>>
>>>
>>>
>>>
>>>
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>
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