[UK-CONTEST] FT1kMP Key Click Reduction

[G3SJJ]

Yes I agree Bob, and as I say the corner transition on trailing edge is 
much better now. I guess what it will mean is people with FT901, TR7, 
older TT, overdriven FT1kD, Russian military stuff etc will be able to 
get slightly closer to me, giving me problems but not getting any in 
return! C'est la vie.

Was just listening to a W1 on 20m, some clix !! Like 3 FT901s in series! 
I'd guess a Tentec user!!

Like I said before, there couldn't have been much wrong since I only had 
one comment in ten years, and a dubious originator at that. Providing I 
haven't made it worse then I can't see my reason to delve further. It 
was a nice technical exercise anyway.

73 Chris G3SJJ


Bob Henderson wrote:
> Chris
>
> As Clive pointed out, key clicks are a rate of change issue.  Edge 
> gradient is the factor traditionally considered but corner transition 
> is equally important.  Recognition of this has prompted a move in 
> favour of raised cosine shaping.  This is used in the K2 and most rigs 
> which use DSP to generate CW.
>
> When I had my pair of FT1kMPs, I applied the Inrad mod to both and it 
> yielded noticeable improvement. Although, I did find significant 
> further improvement could be had with the W8JI mod.  A comparison of 
> the two shows them to be remarkably similar.  The key difference being 
> that components are selected on test for the W8JI implementation and 
> preselected nominal values for Inrad.  The difference between and 
> "tailor made" and "off the peg", I guess.
>
> Should you find the result not quite as good as you'd like, you might 
> take a look at W8JI's version.
>
> GL
>
> Bob, 5B4AGN
>
>
> ----- Original Message ----- From: "G3SJJ" <g3sjj at btinternet.com>
> Cc: "UK Contest Reflector" <uk-contest at contesting.com>
> Sent: Sunday, March 04, 2007 4:28 PM
> Subject: Re: [UK-CONTEST] FT1kMP Key Click Reduction
>
>
>> Yes, I agree, Clive. I have completed the Inrad mod, 2 C and 1R. The
>> leading edge has only changed slightly but there is a very noticeable
>> improvement in the trailing edge. Before there was a sharp corner
>> whereas now it is much more rounded. I have taken pix of the waveform if
>> anyone is interested.
>>
>> 73 Chris G3SJJ
>>
>>
>> Clive GM3POI wrote:
>>> Chris,
>>> The more important check you can make are the corners of the 
>>> waveform. You
>>> do not want any sharp corners, whilst rise and fall times effect the 
>>> click
>>> pattern you should be more interested in the roundness of the waveform
>>> corners.
>>> 73 Clive GM3POI
>>> ----- Original Message ----- From: "G3SJJ" <g3sjj at btinternet.com>
>>> To: "UK Contest Reflector" <uk-contest at contesting.com>
>>> Sent: Saturday, March 03, 2007 11:52 AM
>>> Subject: [UK-CONTEST] FT1kMP Key Click Reduction
>>>
>>>
>>>
>>>> I am in the process of dong the Inrad key click mod. Just about to
>>>> solder in the 0.1uF on to the RF board. Before I do that I was
>>>> wondering if any one had any views about which components do what?
>>>>
>>>> A check on my scope revealed that both positive and negative going
>>>> leading edges were virtually text-book waveform, with about 6-8 mS
>>>> rise-time. My scope hasn't got storage facility. The trailing edge is
>>>> not so good with probably around 1-2 mS which will produce some clix,
>>>> (though with one comment in 10 years it can't be that noticeable!!)
>>>> Obviously I need to tame the trailing edge, but ideally I don't 
>>>> want to
>>>> lengthen the leading edge and make it too soft a sound.
>>>>
>>>> Any thoughts.  Chris G3SJJ
>>>> _______________________________________________
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>>>
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>