Re: [drakelist] R-4B Passband tuning alignment

[Rocco Lardiere]

Chris,   The little springs tend to slip a bit; you think you are moving the drive shaft and slug, but you are only moving the spring.  Try a small, stong alligator clip inserted from the rear of the receiver - this is much easier to adjust than pliers.  Try to clamp back on the shaft to prevent spring slippage.  Sometimes you have to break the slugs loose a little.  Once you have one moving (it should obviously affect the AVC voltage at TP-2), you can complete the alignment for that slug.  Read the book carefully, especially regarding the dots on the front panel.  It is easy to make mistakes regarding the positioning of the knob and where to peak the spring shafts.  You SHOULD be able to peak those four springs - all of them.  You should repeat the adjustments until you have no further improvement.    Be very gentle and careful with all of this.  You do NOT want to break anything.    This bit of the alignment is often found to be screwed up on the early R4 series receivers.  Getting it right can really perk up the receiver.  If done properly, the bandpass will work as you would expect, and the selectivity should be very sharp, especially in the CW position.  It isn't a crystal filter, but it's close.    If you are certain the alignment has been done correctly, and you still have strong asymmetry between sidebands (one side down several S units from the other), you may have other alignment issues.   Other list readers may have some other pointers on this adjustment.  It is a common problem.   73,   Rocco N6KN ----- Original Message ----- From: Chris Codella To: [EMAIL PROTECTED] Sent: Saturday, January 24, 2004 5:25 AM Subject: [drakelist] R-4B Passband tuning alignment I recently went through the alignment procedure in the R-4B manual completely.  Turned out my R4-B wasn't too far out.  But the passband tuning isn't quite right - sounds unsymmetrical and a bit leakier that I think it should be.  But I have questions about this part of the alignment procedure as it's the only part I had trouble with. There are, it seems, 5 adjustments in the back of the passband tuning unit: the 4 individual slugs and the center screw.  The screw is no problem.  But the manual (p.34) isn't very descriptive about how one goes about adjusting the 4 slugs.  It just says to adjust them for maximum negative voltage on TP-2.  Can anyone here shed some light on this? The slug ends that stick out the back seem to be tightly coiled springs with flattened tips.  When I attempt to turn them with pointed tip pliers, the spring shafts just coil or uncoil and the slug doesn't actually turn.  Is there some trick to this?  A special tool maybe?  The manual does warn about it, saying: "These slugs have a tendency to spring back after being turned, so care must be exercised to be sure the settings giving maximum voltage is made."  Not much help when the slugs don't seem to actually turn at all. Thanks, Chris, W2PA