[UK-CONTEST] Key clix

[G3SJJ]

Several people, including myself, commented on key clix in AFS. I have 
been observing this problem around the bands for sometime now. It is a 
difficult one since simple key click filters are really things of the 
past and for the most part we have to rely on manufacturers, which 
hasn't proved very successful.

Some of the older radios, like KW2000B, TR7 and FT901 were notoriously 
bad. Icom and older Tentec are also not so good. I think the FT1kD was 
bad if over driven, and the MP also has a sharply falling trailing edge. 
These fade into insignificance though when you listen to some of signals 
from former Soviet bloc states. I am also coming to the conclusion that 
some big Eu contest stations deliberately widen their signals on both 
modes to maintain a clear channel. I certainly don't agree with that. 
Whilst I felt aggrieved when hearing some of the clicky signals over the 
weekend overall I don't think we were doing so bad. I think, though 
there are a couple of things we can do to reduce clix -

a - fit a mod if available for our radio
b- look at amp switching

I was just looking at the pix I took whilst doing the Inrad keying mod 
last year on my FT1kMP. The leading edge was almost perfect before, and 
the mod softened it up slightly. The trailing edge had  a very sharp 
edge before but nicely round after. I went with the values suggested by 
Inrad but I think on reflection I would have been a little happier with 
slightly softer trailing edge. I intend putting the scope on the output 
again this week to confirm it is acceptable, and also will check after 
the amp, but supposedly being linear it shouldn't affect the waveform! 
(W8JI has a more comprehensive mod but I opted for the very easy Inrad one)

The other thought I have had is amp switching. There are certainly some 
really thumpy signals about these days. Quite often when you are trying 
to works some DX in a split pile-up, you can copy one of the callers 
with his thumps and clix.  I came to the conclusion that maybe it wasn't 
just the radio, but also the amp keying that contributed to this. In 
fact, going one further, I just wonder if some people are trying to run 
break-in with an amp which has relays not suitable for this. For 
example, TL922 or similar, that kind of technique would explain some of 
the really atrocious signals around.

Another thought is how the tx switches the amp. I exchanged a couple of 
emails with Alex GM3ZBE today as I had noticed some "spits and spats" 
around his signal. Interestingly he remarked that he was hearing relays 
clunking in and out on the Quadra just like using old style Vox, rather 
PTT keying from the Winkey. Again I think that is an interesting 
observation. Probably with higher CW speeds these days there is some hot 
switching taking place especially when using VOX switching.

Here I use PTT keying from the mHam Keyer (WinKey) so the amp switches 
on before a signal reaches it, I use the solid state relay in the MP and 
the TX Inhibit cct is coupled to my Acom 1K amp.

Just a few thoughts which might help to explain why we get hot under the 
collar about key clicks. Strange but I recall writing a sheet of 
foolscap (!) on key click filters for my RAE in May 1963, it was all so 
much simpler then!

Chris G3SJJ