Topband: Ft1000/Ft1000D CW APF Mod

[K1ZM@aol.com]

Hi Gang

Lots of interest in this one.  In order to do this mod, you will need to 
locate the three resistors on the AF board and this really does require a 
picture - I cannot describe it in words.

Thus, I can provide a FAX of the Yaesu datasheet to anyone with a FAX number 
(and have offered to do this to all who have written me).  

Yaesu USA can also provide the datasheet I am sure.  If you go this route, 
pse call Chip Margelli at 562 404 - 2700 ext 250.

The datasheet is:

File Number  TSN-9316
Date: 2 July 1993
Model: FT1000 series
Series: Range Mid-late 20's lots
Problem: Howling (self-oscillation) during CW APF operation (yeah right!!!)

You need to change three resistors to their ORIGINAL VALUES:

R 3062  to 6.8K ohms
R 3065 to 470K ohms
R 3067 to 100 ohms

You will probably find 18k/220k and 330 ohms respectively in your FT1000.
(That is what I removed yesterday).

Yaesu advised me that I would find 12K/330k and 220 ohms respectively in my 
radio.

(I obviously did NOT find those values - which leads me to believe that they 
have "played" around with the values in the CW APF circuit any number of 
times now since this data sheet was produced in 1993!  No wonder the CW APF 
performance is "all over the lot" on various FT1000D's I have listened to 
over the years!!)

But what you WANT is 6.8K/470K and 100 ohms - these are what I installed 
yesterday and I can report that they make a WORLD of difference!!

So, just give me a FAX number and I will send you a FAX of the data sheet.  
If that route doesn't work for you, pse send me ur adr or an SASE, and I'll 
get you out a copy of the datasheet right away.

BTW, to some, this restoration produces what they might call "ringing" in the 
CW signal received.  It is arguably a personal preference as to what 
constitutes "ringing".  But with proper adjustment of the IF SHIFT knob  - 
the black knob located just below the CW APF knob  - (I find two clicks to 
the RIGHT of center detent works best), I do not find this ringing 
objectionable.

Once properly adjusted on a target signal, if you quickly switch the APF IN 
and OUT, you will experience an **enormous** difference in HEARABILITY - 
which to me on 160M is what it is all about.

Tks to all who have written.

Faxes headed ur way....

73 JEFF

K1ZM@aol.com
 



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