[R-390] need help with390A RF dedk

[Flowertime01 at wmconnect.com]

Russ,

Take the time to down load a copy of the Y2K manual first.
It is much easier to read for your introduction to the R390/A theory of 
operation,alignment, repair and adjustment.

Also down load a PDF copy of TM11-5820-358-35.

Put both of those documents on a CD for future reference.

Do not force any thing.

The RF deck will run over and go forever on the cams and RF deck switch.

But the parts almost never get operated that way so they may not like to get 
pushed.

The PTO will hit hard ends and can be trashed if the 10 turn KC stops and PTO 
are out of "sync, alignment mechanical adjustment" The PTO will do about 11 
turns plus and is normally set to the 10 turn KC shaft stops keep the PTO from 
ever hitting an end point.

The RF deck clamps come loose, Clamps break. The dial counter bevel gears 
skip if not positioned well. Gears clamps slip and rotate on the shafts.

There is a 10 turn stop on the MC shaft.
Close your eyes do this by feel, ignore that counter.

Grab the MC now and run it either CW or CCW to a stop.
Then run it the other way and count off the 10 turns.
About 3 detents per turn or 30 MHz. at one Mhz per detent position.

If you do not get 10 turns you need to start inspecting for dirt, friction, 
and other binding problems. You can remove the RF octave slug carrier springs 
and pull the slug carriers for the six RF octaves and two variable IF slug 
carriers. One of these may be binding and causing problems. Do not mix your slug 
racks up. All RF slugs are not the same. Hanging the .5 to 1Mhz slug rack into 
the 16Mhz to 32Mhz position will fit but the receiver performance will suffer. 
IE the receiver goes deaf but looks OK.

Full CW is 00 MHz. The knob should go a bit past the detent.
Go CCW seven detents. That's 7 Mhz.

Grab the KC knob and dial out some where a full turn off its 10 turn end stop.

Grab the zero adjust and engage it.

Grab the KC knob and find the kind of feels good center of the zero adjust.

Disengage the zero adjust.

Run the KC knob up to +000.

Run the KC knob to the stop.

Read the dial number.

Back the KC knob off 35 from the max number.

Your RF deck mech is set at 7.+000.

Eye ball the cams and alignment points.

There should be holes in the cams (near their high point) and black lines 
painted and over lacquered on the front of the RF deck.

Most of the cams should look good.
The .5 to 1Mhz may be off because the middle of the zero adjust is subjective.

You likely have a cam way off that is your clue you have a slipped alignment.

If the receiver dials the KC and MC a full 10 turns each then the dial 
counter gears may have just slipped. You drop the front and reset the counter. You 
can reset the counter through the front bezel but its a bit of a struggle to do 
so.

Read the Y2K and then the TM on the mechanical alignment.

The Fellows did a real good set of mechanical gear drawing for the Y2K manual.
That information really shines.

If you have a sline wrench you can reset the alignment your self in a few 
minutes.
If you need a sline wrench ask about that here.

A short sline can be turned into a long sline with some long hex bit drivers 
that have the allen hex bit removed and a length of spline key installed.

If you need a clamp you can ask for some help here on the reflector and see 
what gets offered. Part are available. They are not free. 

Read about the anti lash springs and split gears. Inspect your RF deck and 
see that all your gears are loaded. Do not over load gears. Just get one tooth 
past slack on the springs. You may want to bend up some springs so you do not 
have to over load the gears.

Read the R390 page and Wei Li's Pearls of Wisdom for some good review and 
coverage of taking care of your RF deck.

http://www.r-390a.net%2ffaq-refs.htm/
Then select tutorials
Then select Pearls of Wisdom

If all else fails by all means send it out to one of the Fellows to get it 
fixed.
If you are with in a couple hour drive of an offer consider giving up a 
Saturday or Sunday to get it done. It only takes about 4 hours to go through a 
receiver. An after noon watching a Fellow walk through a receiver is an education 
that will stay with you for the rest of your life. Every R390 owner should 
have the opportunity. The VCR tapes are also a great education.

Let us hear how the project is going. You do not know how many Fellows read 
these pages just to share your hobby experiences with you.

Roger AI4NI




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