----- Original Message -----
From: "Bill Tippett" <btippett@alum.mit.edu>
>
> 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:
http://www.dellroy.com/W4EF'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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