Topband: FT1000 CW APF Mod - For Weak Signal 160M Dx CW Work

[K1ZM@aol.com]

Hi Gang

I'll try my best to make this one BRIEF.

In 1992-1993 I purchased 3 new FT1000D radios.  I loved them for weak signal 
CW work on 160M - especially the APF audio peaking filter in the FT1000 and 
FT1000(D).  It often made the difference between NO HEAR on 160M and hearing 
the weakies WELL on CW mode.

Fast Forward to August 1998

In August 1998 I picked a LATE MODEL FT1000D and was totally DISAPPOINTED 
with how the CW APF audio filter worked.

It was LOW Q - broad vs a former SHARP peak - and half the audio output 
disappeared from my headphones whenever I turned on the APF!!!

Totally downtrodden, I called my friend of 20 years, CHIP MARGELLI, at Yaesu 
USA and asked "How COME???"

Chip laughed his buns off and said some BOZOS had complained about the 
ringing in the CW APF (it doesn't ring - but it **does** produce a higher 
pitch audio output when it is "on" vs when it is "off") - and he said Tokyo 
had mandated a circuit change in the radio as a result.

He sent me a data sheet that would tell me how to restore my 1998 vintage 
FT1000D to my 1992 series circuitry.

It turned out that three resistors had been changed on the audio board that 
dramatically LOWERED the Q of the APF unit circuit - thus the broad as a barn 
peak and poor performance.

(In fact, I have noticed at several contest multis whenever I use ***someone 
ELSE's** FT1000D's - that they literally suck with the CW APF on!!!  So, the 
mod (eg: the Q change of the APF circuit) sure worked to screw up a great 
radio!!!.)

Well, today, I finally took the time to pull the audio board out and swapped 
out the 3 resistors.  This took me quite a long time because 
MICROELELECTRONICS soldering work on almost INVISIBLE resistors is not my cup 
of tea.

But I got it done - and MAN - what a difference!  The performance improvement 
was more than REMARKABLE - my late model FT1000D now works just like the 1992 
vintage series - and FAR BETTER for weak signal CW work on 160M.

If anyone has a late model FT1000 or FT1000D (probably from late 1993 or 
early 1994 onwards), email me and I will tell you how to fix this problem. 
The way to tell if your radio was "butchered" by Yaesu Tokyo is to turn on 
your APF and listen.

If it sounds MUFFLED, if the audio output level DROPS, and if when you rotate 
the APF vernier knob on the front panel,  & you find the audio peak is BROAD 
and not sharp, then you have one of the "newer" versions of the circuit - the 
one which is awful.

Making this mod will restore this radio to one of the finest CW Rx's on the 
market today.

I am tickled pink about what I achieved today.  And, I am **kicking myself** 
for not tackling this one sooner - but since this radio is my **80M** radio, 
I procrastinated 18 months until today to take this project on.

73 and again, if you have an FT1000 or an FT1000D - (I know diddly about the 
MP - as I never have used one) send me a private email and I will tell you 
how to fix ur radio.

JEFF

K1ZM@aol.com



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