[1000mp] Key Click Mod

[Ian White, G3SEK]

Earl wrote:
>
>"I noticed that the INRAD mod consists of 2 capacitors and a resistor 
>and appears to be simple to do.  The W8JI mod looks like it consists of 
>a couple more components and a nightmare to install.  (Probably not, 
>just seems that way.)  Why is there such a difference in the two mods and
>which one accomplishes the task the best?"
>----------
>I first did the INRAD "keying improvement" mod to my MP.  It reduced 
>the clicks from +/-2500 Hz to +/-800 Hz.  Better, but still not good. I 
>then did the W8JI click mod and the clicks are now +/-300Hz.  I am now 
>satisified.
>
>The W8JI mod is NOT a nightmare to install!  Just as many screws and 
>nuts and plugs must be removed for either mod.

Correct! It really is not difficult.

>The W8JI mod just requires a
>few more components.

The W8JI mod can be simplified a little. Tom originally ran a wire out 
from under the RF board so he could experiment with the capacitor value. 
Since he found that 0.1uF works well enough in all cases, there's no 
need to run that wire. Simply solder the extra cap across the existing 
capacitor underneath the board, and put the board back as you found it.

The IF board is even easier to flip over and solder on a wire.

W8JI's other components connect to that wire. The two trimpots and two 
capacitors can be mounted on a piece of perf-board, next to the IF 
board. The perf-board can be fixed to the chassis by sticky foam pads - 
no holes required.

The Inrad mod uses fixed-value components instead of the trimpots 
(values are given in the PDF on the Inrad website) and these will make a 
significant improvement. But as Earl and Bob say, you can make it even 
better using the trimpots.

Just listen to the clicks on a second RX, and twiddle until it's clean 
as you can make it. The adjustments affect the 'make' and 'break' clicks 
differently, so use a hand key so you can hear the two kinds of clicks 
separately.

Come on, folks - it's only five components. No metalwork, welding or 
heavy machinery required.

Or if your eyes, hands or lack of experience genuinely prevent you, then 
surely you know someone who can do it for you?



Earl said:
>Without the mod, if the operator goes on CW in the CW portion of the 
>bands, his wide CW bandwidth violates FCC regulations, IMO.

Or if the big stick doesn't work, how about your self-respect and your 
on-air reputation?



-- 
73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)
                            Editor, 'The VHF/UHF DX Book'
http://www.ifwtech.co.uk/g3sek