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  • #10553

    Rod Matthews
    CVRS Member

    I’m working on a Rogers 12-70 AM radio. It has a dual tuning arm. I took it all apart in some soapy water because it was solid with gunk. Now I don’t know the order it goes back together. The spring goes in first and the fine tuning rod goes in last. That leaves a small ball bearing and a cylinder with a cup on one end. The three large ball bearings press against the ball on the rod, keeping it from falling out and provide friction to move the coarse tuning rod.
    The Puzzle: Does the ball bearing sit on the spring, held down by the cylinder? Or any combination of that?

    Thanks,

    Rod

    • This topic was modified 1 week, 2 days ago by  Rod Matthews.
    #10559

    Dan Walker
    CVRS Member

    Hi Rod. I have worked on several of these , but I do not remember exactly which way they go together.
    When I take them apart I usually write down what goes where. I know how you feel.. I would have to take one of my extra ones apart to know for sure.
    If you don’t get it. email me and I can take one apart .. [email protected].
    Dan in Calgary.

    #10560

    Rod Matthews
    CVRS Member

    Thanks for the offer, Dan. Perhaps there’s a logic to this. Should the ball bearing always go against the spring? I can’t see any wear spots on either end of the spring. I’ll keep playing with it.

    Rod in St. Albert

    #10570

    Dan Walker
    CVRS Member

    I have a spare one of these [not in a radio] , so if you have not figured it out I can take it apart and have a look. It is easy when it is not in a radio.
    Let me know Dan in calgary

    #10571

    Rod Matthews
    CVRS Member

    Dan,
    That’s great. Please tell me the order the parts go inside the coarse tuning arm. And witch way the cylinder goes.
    Thank you very much,
    Rod

    #10572

    Dan Walker
    CVRS Member

    Hi Rod:
    I took mine apart and here is the order it goes back together.
    I would suggest you use a little lithium grease to lubricate the spring and small bearing.
    First, put in the spring
    Second insert the small cap. It should fit inside the spring.
    Third put the small bearing on top of the small cap { it does not want to stay there by itself} Some grease might sort of hold it there.
    Fourth Apply some grease in the three holes [to hold in the three bearings]
    Fifth Push the fine tuning rod hard against the small bearing and insert the three bearings [while keeping pressure on the rod]
    push the large cap over the whole assembly. It keeps the large bearings IN It will sort of click together.
    If the small cap does not fit inside the spring, then you might have a different type than the one I took apart.
    I can’t tell by your photo [if your cap has a small shaft that would go inside the spring]
    This is no easy feat as you almost need three hands, and I suggest you do this over top of a large white sheet, as parts will get away from you.
    [SMALL BEARINGS ROLL AWAY]
    I hope this helps you out
    Dan in calgary

    #10573

    Rod Matthews
    CVRS Member

    Oh, my cap does not fit into the spring. I like the idea of using grease to stick it together.
    I think I’ll try screwing the large cap on the same time I assemble the whole thing.
    While I’ve got you on the line; I removed two old batteries. bias cells. My friend said to use 1.5 volt coin batteries in the cups provided. I can’t find any 1.5 volt batteries like that. Can I try 3.0 volt batteries?
    Thanks for your time,
    Rod

    #10574

    Dan Walker
    CVRS Member

    You must have a little different one than I do..
    I would attach the large spring, the large cap and the C clip on the end of the assembly before I tried to put the smaller parts together. it is easier that way.
    As far as the bias cell is concerned. you can’t use a 3 volt battery. it will give you a terrible hum..
    The bias cell puts a bit of negative voltage on the grid of the tube. Here are some photos of the battery holder I use.. It is a battery holder for a 3 volt battery, but the 1.5 volt battery I use is too small, so I use a hot glue gun to keep the 1.5 vole battery in place.
    Make sure you get the polarity of the bias cell correct. you can buy these 1.5 volt batteries at almost any dollar store. They are watch batteries.
    I am sorry I can’t help you any more with the tuning assembly.
    Dan in Calgary.

    #10577

    Rod Matthews
    CVRS Member

    Dan,
    Thank you for all of your help. I’ll try your combination first then maybe play with the order.
    My battery holder is like the lower one in your photograph. I’d need an extra fat watch battery.
    Thanks,

    Rod

    #10598

    Dan Walker
    CVRS Member

    Rod;
    Here are a couple of photos I have of another one I had apart. It looks the same as yours.. I believe that the small round piece goes in after the spring,
    with the cupped part facing up so the small bearing can sit in it.
    So the order would be spring——-small cupped piece—–small bearing, then the shaft. Then put in the three large bearings. [that is the challenge and the hard part]. I hope this make a difference.. Email me with the results, as it is hard to find my posts on this forum. [email protected].
    Dan Walker in Calgary.

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