[AMPS] TS-940S/AT Spurs?

[i4jmy@iol.it]

Is not the cable legnth from RTX to external tuner close to a quarter 
wave on 10m ?
Where do you look at SWR to set external tuner settings ?
Try to connect RTX and tuner with a different cable lenght (not 
necessarily long) or to monitor SWR using the meter built in 940.
Most practical solution if nothing elese works is just to leave the 940 
tuner ON since it performs the required separation/phase-shift between 
PA output and external tuner.

73,
Mauri I4JMY




> ---------- Initial message -----------
> 
> From    : owner-amps@contesting.com
> To      : <amps@contesting.com>, "Gary McAdams" 
<g.m.mcadams@worldnet.att.net>
> Cc      : 
> Date    : Tue, 12 Sep 2000 11:10:25 -0400
> Subject : Re: [AMPS] TS-940S/AT Spurs?
> 
> 
> 
> 
> > in conjunction with the external everything would be OK, just as it 
was
> > with the 120. That kind of leaves me with the impression that some 
kind of
> > spur is being generated internally in the 940, and only on ten. I'm
> > thinking that the internal tuner usage suppresses the spur and all 
is OK
> > at the tuner. All reports on ten are that the rig sounds fine, and 
no
> > complaints so far about out-of-band signals.
> > 
> >  Short of putting the rig on a spectrum analyzer, how can I verify 
this
> > suspicion?
> 
> Hi Gary,
> 
> It is not unheard of that solid-state PA stages oscillate when 
> connected to some loads. In particular this would be true with a 
> high Q external load.
> 
> Solid state PA's normally have a lot of internal feedback. The off- 
> frequency reactance in a high-Q load can cause phase shift that 
> produces regenerative feedback.
> 
> I suspect you have that problem.
> 
> You might cure it by using a lower load Q, but unfortunately the 
> Nye tuner leaves you stuck with only one Q setting. You might try 
> adding a long chunk of extra coax between the rig and the tuner.
> 
> 
> 73, Tom W8JI
> w8ji@contesting.com
> 
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