Conference vmszoo::rc

EARTH::SCANTLEN                                      21 lines   2-JUN-1987 12:21
                             -< Mini-Flight-Pack >-
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    I installed a Tower Hobbies Mini Flight Pack in one airplane a couple
    years ago, and used my Futaba as transmitter, with no problems.
    It is possible that if you have no problems with the original receiver,
    that the transmitter is 'out of tune' with respect to the Mini Flight
    Pack.  Typically, the transmitter is tuned, and then the receiver
    is tuned to match the transmitter output for peak signal reception.  
    If the original receiver was 'mis-tuned' due to a transmitter set 
    up away from nominal, then an apparent incompatibility would exist
    with another flight pack, when in reality it was really the
    transmitter at fault.  
    
    In the case where you buy a replacement flight pack, the receiver
    is tuned to 'middle of the road' where it should work well with
    all equally tuned transmitters of the same frequency and modulation
    technique.  
    
    In any case, don't attempt to retune your transmitter, (RF section),
    as without proper equipment and license (at least in the States),
    its not allowed.
    
    

        The only thing I've ever built where micro servos wouldn't hack it
        was an RC car. The micro servo just didn't have the torque for the
        steering. Standard (cheap) Tower servos now work fine.
        
        Forgot all about tuning, and I should have mentioned it in my
        earlier reply. As a matter of fact, we did have to tune my friends
        mini Tower RX to match his Futaba TX. Untuned, it had the short
        range you mentioned. Once tuned the antenna down range was farther
        than the yard length. We did it in my yard, to avoid all the metal
        in the house, and the biggest problem was seing the scope face in
        the bright sun. It isn't too hard to do; I will see if I can find
        the instructions I have, and post a note on RX tuning. Scopes can
        be borrowed from your friendly local F/S person. 
        
        As was mentioned earlier, you must have an FCC license to tune the
        transmitter. If you have a ham license, and use the 50MHz RC
        channels, you can tune those yourself (I do). The simple solution
        is to not mess with the transmiter (unless it has a problem), and
        tune the receiver to the transmitter. This is the only way to do
        it when you have more than one flight pack that you use with the
        same transmitter. 

CLOSUS::TAVARES "John--Stay low, keep moving"         4 lines   3-JUN-1987 10:45
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Bob, where did you take the output for the scope?  I haven't
opened my receiver case, so I don't know how the circuit is laid
out.  I would assume that you took it off the detector, ahead of
the agc???

    there is a lot of similarity in radios now adays, since almost all
    manufacturers utilize the same National Semiconuctor RC encoder
    and decoder chipset.  I have a Futaba radio that works just swell
    with a receiver I bought from Tower Hobbies (which, I am told,
    also works quite well with Airtronics radios, too)

My JR FM is not compatible with my Futaba FM - both
on the same frequency.  I was talking to an outfit
in California the other day and I asked why they
stopped making 2 channel receivers.  They said because
too many radios didn't send Aileron and Elevator on
channel 1 and 2 anymore.

If you don't know for a fact they are compatible
don't assume they are.  If you buy a receiver make
sure the seller agrees that it will work with your
transmitter.

Bye
Kay R. Fisher

    Speaking of tuning.....this past weekend, I managed to snap off
    about 8" of antenna from my radio.  How is this going to affect
    the reception of the signal?  Can I just splice a piece of coat
    hanger at the break or what?
    
    Ken

    Ken,
    
    I assume yer' referring to the Tx antenna as splicing coat hanger
    wire into the Rx antenna seems a little radical. :B^)
    
    Here's a better way to repair the broken Tx antenna:  Most likely,
    the tubular antenna was crimped flat at the point of breakage; use
    a scribe or whatever to restore the round cross-section to both
    pieces.  Then, cut a piece of brass tubing sized to telescope inside
    the broken section and extend 1/2" or so either side of the break; 
    carefully tin the brass tubing with rosin core or sta-brite silver
    solder (you may have to sand down slightly after tinning to get
    the brass tube telescoped back inside the broken antenna...leave
    as much solder as you can).  Now, insert the brass tube inside the
    antenna so it's length is centered on the break; apply more flux
    and sweat solder the antenna back together.
    
    Your antenna is now restored back to it's original, correct length
    and, if you're careful with the repair, it may still collapse fully
    as before.  I've used this technique personally and can vouch for
    its effectiveness.    

      |
      | |      00	 Adios,      Al
    |_|_|      ( >o
      |    Z__(O_\_	(The Desert Rat)

    
    This might not be the right note but it's close. I just bought a couple
    JR radios channel 15 and 19. The RX is marked "LOW-BAND 72.xxx-72.yyy".
    Does this mean that I can NOT put a "HIGH-BAND" channel crystal in it,
    like 36 which is not in the 72.xxx-72.yyy range. The owners book breaks
    out what is high band and low band channels but it conflicts with the
    marking on the RX. Does this mean the RX is just tuned for low-band or
    is it different. My airtronics radio never differentiated the two.