Topband: ft1000mp mkv key click mod

Michael Tope W4EF at
Sat Dec 31 13:50:33 EST 2005

----- Original Message ----- 
From: "Bill Tippett" <btippett at>

>         If my memory is correct, Yaesu implemented Inrad's
> mod in all MP's after about August 2004 (or 2003?)  Tom's
> own site says his MP mod takes it from being one of the
> worst to one of the best, so I am not sure why he is so
> negative on the Mark V unless there were some circuitry
> changes from the original MP to the Mark V and Field.  Inrad's
> mod makes me think not.
>                                         73,  Bill  W4ZV

Tom's modification makes a big difference on the falling edges 
of keying envelope and the rising edge of the intra-charcter 
keying envelope:'s-Ham-Radio-Page/FT1000MP-MKV/FT1000MP-MKV.htm

Where it doesn't help is the rising edge of leading characters.
This includes the first character in a message and the first 
character after a inter-word pause. The problem is the ALC 
loop which has to compensate for way too much gain in the 
TX chain. You can fix this by connecting a variable negative 
DC power supply to the external ALC input and adjusting the 
voltage for a proper "ALC pre-set". When I did this on the 
bench (per Tom's suggestion), the leading edge keying 
envelope looked very good (smooth transition w/about 5ms rise 
time). This gets rid of the leading edge click. It's a very touchy 
adjustment, however. You need to increase the pre-bias until 
the drive level just starts to drop (having a monitor scope 
helps). I have been meaning to try to package this ALC fix 
in a little external p-box with a "drive knob" on it, but I have 
been too busy with other projects. Tom mentioned recently
that he was working on a plug-n-play fix for the FT-1000MP 
MKV which will be much easier to install than his current 
modification I don't know for sure, but perhaps he will address 
the ALC problem with this new mod. kit. 

73, Mike W4EF...........................................................

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