[R-390] RF deck removal

[Craig Heaton]

Alan,

 

Where Oh Where to set the MC & KC knobs? I have to agree that Murphy is lurking in your lab/shack. No matter what, the front panel has to be removed in order for the RF deck to come off of the mainframe. Bottom line is; “IF the mechanical alignment isn’t right, ain’t nothing right”. Presetting MC & KC for (Seven…..Plus……Zero……Zero…..Zero) at the getgo enables one to see the cams & index marks ASAP. If all is good, add that event to the day’s blessings. If not, you have another challenge in life! 

 

At that point, don’t let anyone attach a drill motor to the PTO  shaft and give it a spin or two. When reseating the RF deck the coupling might be a few degrees off. Take caution not to bump the PTO shaft. If for any reason the PTO shaft is going to be turned, all is not lost. Quite simple to use a sig-gen to input a signal, turn on the BFO, loosen one of the Bristol screws on the Oldham coupler, turn the PTO shaft to zero beat. That should get you back into the ball park. 

 

Not sure if Chucks video or the Y2K has the following? With the panel down, check/adjust the Zero ADJ device for middle range of movement. On Chuck’s website, he at one time had added a last step to the IF alignment procedure. Which was how to adjust the BFO; zero beat with a 455KC signal injected into the IF.

 

The hardware issue: Hams use what is in the junk box!!! With luck the threads are okie-dokie and there is a store in town with the correct fasteners. Good Luck……………

 

Craig,

 

 

 

From: Alan Victor [mailto:amvictor at ncsu.edu] 
Sent: Friday, October 10, 2014 5:15 PM
To: Craig Heaton
Cc: r-390 at mailman.qth.net
Subject: Re: [R-390] RF deck removal

 

Thanks, all good inputs. Nice to know about the backlash spring and the ball point pen substitute! 

 

Actually, before I drop the panel and pull the RF deck out, all the other modules will be out anyway. Namely, IF deck (already out) fixed one item but may as well look for any other bugs that are obvious. The power supply and the audio deck taken out as well. Main reason... I need to move the receiver from the lab bench to the workbench. Getting down to about half its weight is better for me alone. And of course, the entire mainframe has not been cleaned at all, so that is the goal. 

 

I guess I need to re visit Chucks video on dropping the panel and the issue of NOT loosing synchronization. While the Y2K says full CCW on MC and KC knob, I was under the impression, I was to set the CAM tips in line as it were at 7+000. That is, set MC and KC accordingly and pull the panel and RF deck at that setting. Not at 00 -963. Am I missing something again? Sorry, but I am a firm believer in Murphy's law. In any case, open to any/all comments. 

 

One last item. My panel hardware was redone somewhere in its life. The Phillips screw heads on the main panel attached to the mainframe are straight head screw and use selflocking nuts. So I suspect the mainframe tap is stripped. They are stainless, but not Phillips. So I need room to get behind the panel to get them out and replace with the right hardware. Another reason to get as much electronics out of the mainframe as reasonable.