[Elecraft] Improvement changes to K2 and K1 transceivers

[Bill Coleman]

On May 8, 2007, at 11:11 AM, Giancarlo Moda wrote:

> See for file: “I7SWX possible changes to K2 and K1
> RTX”. It is possible you need to be a member.
>
> The documentation reports suggested changes:
>
> 1)Front-end mixer replacement and roofing filter
> addition. These mods have been implemented and tested
> by I0CG in his K2.

Part of the beauty of the K2 is that it is a very simple radio,  
superbly executed. (To paraphrase a comment K9AY said to me before I  
bought one)

The K2 uses a TUF-1 balanced mixer with close attention to the  
injection levels and impedance matching. You'd be hard-pressed to  
improve the mixer performance for HF.

Since the K2 is single-conversion, the primary crystal filter IS the  
roofing filter. The primary crystal filter is pretty darn good for CW  
or RTTY.

> 2)Demodulator replacement.

What would you do to replace the product detector? Since the dynamic  
range of the signals after the AGC of the IF stage is pretty limited,  
the NE602 is a pretty good choice. It wouldn't be easy to do better,  
especially at the price point for the K2.


Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
Quote: "Not within a thousand years will man ever fly!"
             -- Wilbur Wright, 1901