[Kenwood] FYI FOR TS940 FET'S

TIM MCGRAW w8btm at cinci.rr.com
Mon Oct 4 06:43:42 EDT 2004


HAS ANY DONE THE FIX AND IS IT FOR REAL ???
> > > BEFORE I SEND MY 940 OFF I NEED TO KNOW 
> > >  TNX W8BTM TIM
> > > http://www.guisard.com/ 
> > > 
> > > recently, a Brazilian ham PY1NR found two factory assembly 
> errors. 
> > > Even the Service Manual, Revised Edition is wrong.
> > > There are two FET's soldered in the wrong position which affect 
> > > directly the overall radio sensitivity and AGC performance.
> > > Probably, all TS-940 will have this problem.
> > > All details, description and pictures are available at
> > 
> > I just tried it.  Well, as stated, I noted about a 10db gain in
> > receive sensitivity, and a lower noise floor.  However, I now have 
> > some strange problem with mode control.  Radio sometimes has a mind 
> > of it's own as far as what mode it's on.  I can be on LSB and then 
> > for no reason it will switch to FM...Then I have to play with the 
> > attenuator to get it to go back onto USB.  Or, I'll loose USB all 
> > together until I turn it off, and turn it back on.  Other times the 
> > VCO goes out of lock, and I get the infamous "dots" on the 
> display.  
> > So, I took it back apart, and resoldered pretty much every joint on 
> > both boards.  Unfortunately, that hasn't cured the strangeness.
> > Next step I suppose is to go through the alignment procedures, and 
> > cross my fingers.  
> > I therefore suggest caution in doing the "correction", or mod. or 
> > whatever you might call it.  These are 20 year old radios, and they 
> > have a history of bad solder joints.  Seems as though any jostling 
> of 
> > the boards carries with it considerable risk of developing other 
> > problems and intermittant conditions.  Bottom line is, if it ain't 
> > broke, don't fix it. Or at least send it out to someone who's used 
> to 
> > tearing their hair out on a regular basis.
> > 
> > Well, time to try that alignment.  It's Sunday, so I have the WHOLE 
> > day, and may well need it!
> > 
> > Kevin-  KC8GIA
> 
> GOOD NEWS!! I came back, and for the heck of it, did a CPU reset-
> Now, all is fine!  I've been running it for the past couple of hours 
> and no problems(yet~).
> As to the receive, it is certainly improved.  It may actually be 
> better than my FT-1000MP!
> 
> In any case, my notes above are still valid.  I don't think that I'll 
> personally try another such improvement.  It's just too likely to be 
> a major can of worms, and I can do without the headache.  
> 
> Good luck to those who go ahead with it!
> 
> Kevin - KC8GIA
> 


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