That's OK. I don't do much transmitting on AM anyway <grin>.
I'll print out your comment and include it with my service manual.
Thanks.
Dave...
On Thu, 17 Jun 1999 donald.s.tucker@exgate.tek.com wrote:
> TB-9521 dated 20 April 1995 says if there is low AM TX modulation to change
> R1258 on the Local Unit board from 10K to 4.7K. If you want a copy give me
> your mail address.
>
> Don W7WLL
>
> -----Original Message-----
> From: David G. Maley [mailto:dgmaley@soli.inav.net]
> Sent: Thursday, June 17, 1999 2:33 PM
> To: Tucker, Donald S
> Cc: wa3gin@erols.com; yaesutech@worldnet.att.net; yaesu@contesting.com
> Subject: RE: [Yaesu] FT-900 Modification for Variable "RF" Gain Control
>
>
> btw....
> What AM circuit change????
> Dave
> WA0ZZG
>
>
> On Thu, 17 Jun 1999 donald.s.tucker@exgate.tek.com wrote:
>
> >
> > I did the resistor value change (3.3K to a 10K)to the blanking circuit in
> my
> > FT-900. The improvement was enormous, but still was not sure it was as
> good
> > as it could be (also did the Yaesu suggested AM circuit change-forget the
> TB
> > number but have a copy if anyone interested). In talking with Yaesu on the
> > phone about the noise blanking mod, I learned that the best value to
> achieve
> > the most effective blanking was not necessarily 10K, but could be some
> value
> > less than, or even slightly more. Since I use my FT-900 exclusively in my
> > car, noise blanking is a prime issue. Wonder if anyone ever replaced the
> > fixed value with a variable value (a 10 or 12K pot) and literally set the
> > value to achieve the highest blanking efficiency?? If so think the FT-900
> > owners would be interested in your experience. Still a great rig, but
> never
> > had the SSB filter, which Yaesu no longer says is available. Understand
> > Irad (?) has one. Is the improvement worth the effort???
> >
> > Don W7WLL
> >
> >
> > -----Original Message-----
> > From: Dave Jordan [mailto:wa3gin@erols.com]
> > Sent: Wednesday, June 16, 1999 7:36 PM
> > To: Yaesu Technical Support; yaesu@contesting.com
> > Subject: [Yaesu] FT-900 Modification for Variable "RF" Gain Control
> >
> >
> >
> > Hi Folks,
> >
> > When I first got my FT-900 brand new in the box I had reservations about
> > owning a rig that didn't have an "RF" gain control. It's been several
> > years
> > now and I'm still missing that "RF" gain control. I have a FT-1000 and
> > I'm just
> > used to cranking it back...it does make a difference in reception. SO,
> > back
> > then I asked Yaesu to give me location for the fixed resistor that
> > controlled the
> > RF gain.
> >
> > Tonight I decided to open up the FT-900 and do the deed. I found
> > a free pin on the "CAT" socket that could be used to install a connector
> > with a
> > pot that I would parallel with the fixed resistor. So, I could unplug
> > the pot and
> > have the normal fixed setting or plug-it in and have some variability
> > over the
> > "RF" gain. As it turns out what Yaesu sent me as a mode was a technical
> > bulletin TB-9448-A, a fix to increase noise blanking performance, by
> > increasing the resistance of R2335 (on the back side of the xthe RF-Unit
> > board number F3251000C. I can scan in the location chart if anyone is
> > interested. R2335 was originally 3.3Kohms but can be increased up to 10K
> > ohms. I added another 3.3K ohms in series. Haven't got the box back
> > together yet but will report out on the results soon.
> >
> > The question to the list and Yaesu technical support is simple. I need
> > the
> > location of the fixed resistor that is responsible for setting the "RF"
> > gain of
> > the FT-900. I would appreciate a fax or email enclosure of the specific
> >
> > loation ASAP...
> >
> > By the way, if you like the idea of a "RF" gain control but don't want
> > an outside connector with pot you could easily disable the sidetone
> > beeper
> > variable resistor and use it for this purpose. Another thought would be
> > to
> > simply use the pot to identify the favorite setting and use a fixed
> > resistor in
> > the plug. I've found that when I do crank back on the FT-1000 the
> > setting is always the same and the only time I turn it up these days is
> > to give a signal
> > report.
> >
> > OK, that is it...thanks in advance for any assistance,
> > dave
> > WA3GIN
> >
> >
> >
> > --
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> > Submissions: yaesu@contesting.com
> > Administrative requests: yaesu-REQUEST@contesting.com
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> >
> > --
> > FAQ on WWW: http://www.qsl.net/k7on/yaesu.html
> > Submissions: yaesu@contesting.com
> > Administrative requests: yaesu-REQUEST@contesting.com
> > Problems: owner-yaesu@contesting.com
> > Search: http://www.contesting.com/km9p/search.htm
> >
>
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