[Elecraft] K2 CW Filter Grounding mod...

Wed Sep 11 11:15:39 2002

Hi

I have built several K2's and I ground the crystal cans by soldering the wire to the board then running the wires up both sides close to the can and flowing solder quickly on the side of the can. I solder only one side of each can, allow them to cool then solder the other side. Any excess wire is then clipped flush with the top of the can so as to not interfere with the SSB module. This technique seems to work for me. As was stated in the original mod description adding the shield wires to the bottom of the board and chip bypass capacitors do not really help all that much so I don't do that part of the mod.

The mod does work and it's effect is measurable with Spectrogram so I think it is worthwhile to do. Elecraft has not approved it probably because of the possibility of damage to the crystals. If you are careful (and quick) you can do the mod safely. You can always buy another set of crystals if you screw it up. I have never had a problem with it and I have built 4 K2's and 3 K1's using the same method.

I have seen crystals with grounding wires spot welded to their cans as an option from the manufacturer. Maybe Elecraft could look into obtaining this type of crystal and then we would not have to risk damaging a crystal by overheating it.  

All of the other mods should be done after the radio is completed except this one. It is much easier to do this mod when building the radio than going back and reheating and moving the wires (much safer for the crystals also)

Don Brown
KD5NDB

----- Original Message -----
From: Tom HammondN�SS
Sent: Wednesday, September 11, 2002 8:28 AM
To: George, W5YR; [email protected]
Subject: [Elecraft] K2 CW Filter Grounding mod...

Sorry folks, last message carried an INappropriate Subject line.

Trying again...
_____________________

GM George:

At 12:05 AM 9/11/02, you wrote:
>Is the delta improvement obtained from grounding at the base instead of the
>top due to the lowered inductance of the shorting wires? And/or their
>parasitic capacitance to other circuit components?

I cannot knowledgeably answer this. However, I suspect that it it due to  
the added lead length, which would tend to imply the first of your two  
choices, above.

>Is it acceptable to ground the crystal cases both at the top and the
>bottom?

If you ground on both sides of the xtal can, as suggested, I don't think  
there'll be any additional available holes for grounding at the top as well.

>Would there be any merit to fashioning some sort of shield can around the
>filter components?

I believe I recall that this has been tried and found to be lacking.

>Getting a K2 in a few days and this mod seems to be of such importance that
>I want to do it right . . .

Were it me, I'd follow the grounding at the bottom recommendations and be  
done with it.

73,

Tom  N0SS

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