[R-390] Staggertuned IF Question

[n4buq at knology.net]

This one has trimmers on both ends of the filters and it has RC across the 
L in the transformers so I assume this one is broadband.  I think I have 
other issues with it, though.  I tried Roger's method of removing the 3rd 
mixer and injecting 455kc at the plate pin.  It took a LOT of signal to be 
able to hear it through the IF deck.  The crystal's trimmer and xfmr don't 
seem to peak like they should and it reqires me to crank the slugs in T501 
and T502 to the near limits to get them to peak.  Switching to AGC 
automatically gets me 20dB on the carrier level meter as opposed to zero in 
MGC.  I'm pretty sure I have work to do...

Barry - N4BUQ

On Thu, 14 Sep 2006 15:05:46 -0400, Mark Huss <mhuss1 at bellatlantic.net> 
wrote :

> I seem to remember that the first run of R-390A (the ones WITHOUT the 
> trimmers on the top of the mechanical IF Filters. The Mechanical filter 
> cover does not have a dimple at the mounting screw) was straght tuned. 
> When Collins did the mod to add the trimmers, they also changed the 
> circuits on the IF Transformers to stagger-tune them. At least that is 
> what I remember from the R-390A classes.
> -- 
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> Some people are like a Slinky .. not really good for anything,
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