[1000mp] MkV key click "half" mod?

Tue, 13 Jan 2004 16:50:31 +0200 (EET)

Guido,

on old MP I tested the effect of modifying the stages causing clicks. I 
modified RF only or IF only and found that RF-keying stage fall time is 
the main problem. So, modifying IF only will not improve clicks.
MKV and MP should have similar keying circuitry. Im not 100% sure about this!

All keying stages are in series. There are three of those. If you switch 
one keying stage OFF very fast then it does not matter what you do with 
the others. The output of the whole circuit is OFF very fast.
The rising edge (of DOT) is different. It is enough that one keying 
stage is slow. Other keying stages can be ultra fast without causing 
clicks. The potential click of the fast stages will not reach the output 
because the one slow stage is just starting to wake up.

73  Juha   OH1NOR

> The W8JI mod (or even the INRAD mod) for the old FT1000MP is not so hard to
> do, but disassembling the 200W PA of FT1000MP MkV is a real nightmare...
> Has someone tried on MkV what happens with the W8JI mod ONLY to IF board
> (with trimmers correctly adjusted), without adding the 0.1uF capacitor to RF
> board FET?
> If a correctly adjusted mod added only to IF board (no capacitor on RF
> board) would be enough, I would be very happy, because I repaired two times
> the RF board of a MkV and disassembling the PA was a panic; now I have to
> "declick" three MkV... :-(
> Any test of it?
> Thanks and ciao
> 73 de Guido, ik2bcp / ab9dg
> 
> _______________________________________________
> List Moderator: Richard Lubash N1VXW
> 1000mp mailing list
> [email protected]
> To Change Options or Unsubscribe:
> http://mailman.qth.net/mailman/listinfo/1000mp