[Elecraft] K2: OK to use a bypass cap on the key?

[Don Wilhelm]

Lenny,

I would not think a capacitor across the key would make much 
difference.  There are other choices - read on.

First of all determine whether the keyclicks are caused by 
RF-in-the-shack or not (so you do not go chasing the wrong gremlin).
Operate the K2 (and any amplifiers you may have been using) into a dummy 
load while monitoring on another receiver with a wire for an antenna - 
space the wire from the dummy load to give an S-9 signal into the 
monitor receiver.
Do you hear keyclicks?  If not, then look for the mentioned cures for 
RF-in-the-shack.

If the K2 (and any amplifiers) still have keyclicks, then I have to ask 
what is the serial number of the K2?  If it is below SN 4060, it may not 
have the keying waveshape mod installed.
If you do have the keying waveshape mod installed, *or* the serial 
number is greater than 4060, you likely have a problem with the K2 
keying area.

(Note that there are a lot of *ifs* in the statements above - observe 
them carefully before digging into your K2).

Currently, the K2 Keying waveshape mod is not available from Elecraft 
because the PIN diode that was used on the RF Board is no longer available.

The new K2s use an SMD PIN diode on a carrier board in place of the 
original PIN diode.
I have the older K2 keying waveshape mod instructions on my computer and 
can email it to any interested parties along with the part number and 
information about how to install the SMD PIN diode if you send me a 
direct email.  I would post the instructions on the reflector, but the 
reflector will not accept attachments for the original instructions.

HISTORY - the basic K2/10 did have some keyclicks that were not 
troublesome until an amplifier (namely the KPA100) was added which also 
amplified the keyclicks.  The K2 Keying Waveshape Mod was designed to 
eliminate those keyclicks.  The first K2 with that keyclick mod added to 
the design was SN 4060.

73,
Don W3FPR

On 6/6/2014 12:09 PM, w2bvh wrote:
> On my K2 Is it ok to put a 1 - 10 nF bypass cap across my straight key?
>
> I've got a 6M KW amp and evidently rf was getting into the key line at 
> power levels over ~350 W and keeping the system keyed all the time.  
> Three turns on  the keying wire (mini zip cord) through a split bead 
> fixed it, but I'm getting on air comments about key clicks.  I'm going 
> to switch to RG174 on the key and intend to add 1 - 10 nF across the 
> key terminals, if its not harmful to the K2.
>
>
> 73,
> Lenny W2BVH