[R-390] An Update - now called R-390A 8-16MHZ Cam Alignment

[Tom M.]

Russ,

Doing 8-16 Mhz first is what I do so also.

You can then adjust all the the other adjustments independently.  I have my overruns exactly the same on both ends, counter set right, etc.

Like anything else, really not that hard if you know what to do.

A simple test to see if your cams need adjusting is to turn the MHZ knob slightly which will cause the cams to move before the band switches, and watch the S meter.  If you get an increase in signal by turning the MHZ knob in either direction it's a pretty good bet your rig can benefit from RF/variable IF alignment.

73 Tom N5OFF



--- On Sat, 4/10/10, wa3frp at aol.com <wa3frp at aol.com> wrote:

> From: wa3frp at aol.com <wa3frp at aol.com>
> Subject: [R-390] An Update - now called R-390A 8-16MHZ Cam Alignment
> To: r-390 at mailman.qth.net
> Date: Saturday, April 10, 2010, 7:38 AM
> 
> 
> 
> 
> First of all, thanks to those who responded with that was
> information very useful in resolving this Cam Alignment
> issue.  I agree that the title of my subject line was
> incorrect. It should have read R-390A 8-16MHZ Cam Alignment
> 
> or R-390A RF Deck Cam Alignment Question or something
> similar.
>  
> 
> Second, it is interesting to note that the detailed
> information that I got about how to align this cam does not
> appear 
> to be present in the Y2K R-390A/URR Technical
> Reference.  So maybe, it should be added.
>  
> This was my problem.  I had always assumed that the
> cam alignment was not in issue with my R-390A. I had not,
> until this
> week, ever removed the front panel.  The top cams
> which as easily visible with the front panel installed were
> OK.  And, I was 
> not chasing a cam alignment issue when I removed the front
> panel. But, I quickly noted that the cams associated with 
> 8 - 16 Mc and 2 - 4 MHz were both out of alignment by 10 to
> 15 degrees.
> 
> One solution offered, was to move the KHz knob to a point
> where the 8 - 16 MHz cam aligns with its mark and make that
> the 
> new center point.  But, that would not work in my case
> as the 8 - 16 MHz cam needed to rotate clockwise by 10 to 15
> degrees 
> which would have put the KHz dial well past 7+0035. 
> So, I started to look at what was needed to remove a minimum
> number
> of gears to leave my Veeder Root counter properly centered
> with the end stops at xx-965 and xx+035 and the 8-16 cam in
> alignment. 
> 
> This is when I noted a novel solution that I have not found
> in the literature on hand here nor in any comment I received
> online. 
> 
> I found that by simultaneously releasing the clamps 16-32,
> 4-8 and 2-4 the four slug racks, associated with 16-32,
> 8-16, 4-8 and 2-4,   
> all fell. This meant that the cam for 8-16 MHz was now free
> and available for adjustment without having to remove and
> reset any
> gears nor jiggle with the ten-turn stops. Could it be that
> easy?  I can't find any negative effect and all of the
> cams are now aligned.
> 
> So, please take a look at this and tell me if the
> documentation should be changed to indicate that (1) the
> adjustment of the cam 
> for 8-16 MHz should always be made first and that this is
> accomplished by releasing the above mentioned three clamps
> and by
> hand rotating the gears until the 8-16 MHz cam is in its
> proper position, (2) temporarily locking the 8-16 MHz cam in
> place by tightening 
> the clamp associated with the 2-4 cam without regard to the
> 2-4 cams position, (3) then individually adjusting the
> 16-32; 4-8; 
> 2-4; 1-2 and 0.5 -1 cams.
> 
> I have to note that the gear I used to hand rotate the 8-16
> cam into position was the large gear closest to the no-mar
> clamp for the
> 16-32 MHz cam. Also, note that this is a split gear and
> that care needs to be taken to assure that both sides of
> this gear remain in 
> place and in contact with its associated gear on the 8-16
> MHz shaft. Otherwise, the split gear will lose tension and
> you will be looking
> to reset both springs that hopefully are still attached to
> the split gear. (This did happen to happened to me).
> 
> Comment?
> 
> 73 de Russ WA3FRP
> 
> 
> 
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