[Yaesu] FT-101EE Modulation Problem

[KN4LF, Thomas Giella]

Walter,
  Thanks for the good info and tips on my FT-101EE problem. I'll get at it
and see what I can find. As far as the Yaesu repair thing, I thought it a
good thread but to bad it had to degenerate into a political thing.

73,
Thomas Giella, KN4LF

Plant City, FL
Grid Square- EL88wx
CQ Zone 5
ITU Zone 8

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----- Original Message -----
From: "Walter A. Hutchens" <waltah@cfw.com>
To: <yaesu@mailman.qth.net>
Sent: Monday, January 21, 2002 5:10 PM
Subject: Re: [Yaesu] FT-101EE Modulation Problem


> Thomas asked:
> > What's been happening is that I'm getting an approximate 100 watts out
at
> > 280 mils in the CW/TUNE position but only approximately 30 watts out at
> > 100 mils on USB phone. Also when I modulate in USB the ALC swings way
left
> > out of range, even with the mic gain cranked way back to 2 or less. This
> > excessive swing ALC happens whether the RF processor is on or off.
>
> Evidently those in the know have been doing as I have and not reading the
> list closely as we struggle with whether Yaesu service does or does not,
um
> ... technical term ... suck.   So you have the second team taking a stab
at this.
>
> This sounds like instability -- something is oscillating but considerably
off
> frequency.   The large ALC response with low gain setting says that the
ALC
> detector (grid of PA, right?) sees it but your wattmeter does not; first
thing
> I'd check is PA neutralization, though I'd expect problems there to show
on
> the wattmeter.
>
> If not neutralization then the bogus signal is getting through the driver
> stage.   However if the problem occurs *only* in USB then some
> considerably earlier stage must also be in the game or may be solely at
fault
> so I'm wondering if it's also on LSB.
>
> Since the problem is only on the new bands, the final mixer stage is the
> earliest likely participant.
>
> If you have access to a spectrum analyzer it will point you in the right
> direction rather quickly -- a heck of a spur is reaching the PA grid and
its
> frequency should announce the stage in which it was generated.   If no
s.a.,
> I'd reexamine the installation of the WARC mod first, looking for
> component location, lead dress and bypassing problems, then checking any
> special alignment requirements.   Yaesu didn't plan for this conversion
> scheme so there's the possiblity of more critical adjustment to avoid an
> undesired mixing product that could lead to instability.   For example
they
> may say something like "Adjust Lxx for exactly 0.2 v RMS at test point"
and
> if so, 'tune for max' could cause problems.
>
> If the WARC mod is okay, recheck the processor.   I did the processor
> install on a -101FX; the only thing I found tricky was that due to its
location
> that board is subject to pressure on the filter if the set is placed
upside
> down with the covers off and I had to troubleshoot some connection or
> broken trace problems.   The details have been lost in the internal
ear-to-
> ear winds ...
>
> Walt Hutchens
> KJ4KV
>
> _______________________________________________
> Yaesu mailing list
> Yaesu@mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/yaesu
>


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