Conference vmszoo::rc

    Steve, Ajai, Eric, Dan, and I will be right in the middle of this issue
    since we will be 5/7 of the BOD of CMRCM for the 1991 season.  We have
    to come up with a plan and a way of enforcing it in a way that is
    acceptable to the club.  My main concern is safety - I don't want us to
    lose our field because someone has an accident that could have been
    avoided.  Any ideas would be appreciated and if any noters that are
    members of other clubs have their club policy, could they please post
    it here.  The winter off season will give us the grace period we need
    to prepare the membership for any changes.  Our frequency system will
    have to be reexamined and our pilot station assignments will have to be
    readdressed.  We will have to educate our members through meetings and
    the newsletter before the weather gets nice enough to fly.  The field
    is usually not very accessable in the winter months.  (The last two
    years have been an exception.)
    
    Charlie
    

I don't want to dilute your goal of a list of what each club is doing
so perhaps we should continue this discussion in a different note but
just to meet your criteria here is what the Orange club - "Mohawk Valley
Modelers".

We have one meeting a year - at the field in the spring.
So we determined last year that we would not disallow odd channels.
Nothing was said of disallowing non-gold radios at the time.

>    Our club has decided to continue to allow non-gold stickered radios to
>    be used at our field.  However, we are *NOT* outlawing odd channels.

I think you did the right thing but...    

>    The leading method is an additive pin system.  Pins would come in two
>    widths, one for 1991 Tx and dual conversion Rx, and one for all the
>    rest.  The 1991 Tx and DC Rx would be the width of the individual
>    frequencies on the board (ala CRRC).  The "old" radios would have a
>    triple wide pin.  

This would be adequate for most purposes but two new problems add risk
to the equation.

1.  Paging systems are popping up all over the band.  Putting out 500 watts
    between our frequencies.  I just got a new scanner and they are
    really out there - thick as thieves - and they didn't have to wait
    for 1991!

2.  An odd transmitter 21 channels away from an even transmitter
    can (and will) shoot down every wide band receiver with a single
    conversion IF strip tuned to 455 KHz (almost all old receivers).
    To be accurate - the mixing of two frequencies 23 channels apart
    does not cause a difference frequency of 455 KHz - actually it causes
    a difference frequency of 460 KHz.  I was just playing with a
    frequency chart and can't for the life of me figure out where they
    came up with the 21 channel arithmetic.  Anyway 460 KHz is apparently
    within the band width of the IF strip and is passed straight thru.
    There are those who would argue that if you filter 455 KHz really tight
    with crystal filters (JR's ABC&W) then 460 is not close enough to
    455.  Anyway the paging system that is 22.5 channels away is on the
    other side of 455 KHz at 450 KHz.  This means that today any RC channel
    can mix with a paging system and produce the same results as the TV
    channel 4 problem.  So if you go scanning (I am) - you have to notice 
    which paging systems are 22.5 channels away from anybody flying.
  
    Of course you don't care if you have a dual conversion receiver!

	So - if you want to fly an non-dual conversion you should scan the
    72 MHz band and record all paging systems.  Let's say you only find one
    at 72.640 (I think that is where the one at Orange is).  Then you
    subtract the IF frequency from this.  72.640 - .455 = 72.185.
    Then you look that up on your frequency chart (I posted one here someplace)
    and you find that 72.185 is exactly between paging channel 19.5
    and RC channel 20.  So you have to outlaw anyone from flying channel
    20 when ever some turkey with a non-dual conversion receiver is flying.

    Of course you don't care if you have a dual conversion receiver!

I was out in the parking lot this lunch hour and after scanning for
about 30 seconds a paging system came up - loud and clear.  And I checked
to and he forgot to put his pin on the club frequency board :-)

I won't even blame the AMA for this - it is the FCC's fault.  If we never
changed anything in our frequency allocation - they are still allow paging
systems between our (still legal today) wide band channels and they will
mix with themselves or our local transmitters and shoot down some (maybe all)
single conversion (455 KHz IF strip) receivers.

What I need now is a scanner with a built in VAX processor...

Sorry if I rambled in the wrong note - Moderator feel free to place in
the correct place.  

Bye          --+--
Kay R. Fisher  |
---------------O---------------
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    Those are valid points and most (all?) of it is true even today.
    
    The membership was made aware and will continue to be made aware of
    potential problems with non-dual conversion receivers.
    
    Al has even published a list of NH area pagers so that people can
    be aware of them...
    
    The suggested method would at least control what we have control over.
    
    We are looking for ways to protect all flyers as much as we can, short
    of funding everyone's upgrade to dual conversion rx.
    
    
    Yes, the 21 channel separation is not fixed by the idea present in .0.
    I am more than open to a system that would take this into account too..
    
    Maybe the frequency chips that we currently use could have the 21
    channel away frequency on the back, so if you are using chan 38, then
    you also have the chan 17 freqency "tied up" because you have the
    chip...
    
    Hmm, this has some potential...  Thanks for the spark...
    
    Yes, dual conversion solves many problems!!  That is why I am moving to
    owning only dual conversion receivers too.
    
    cheers,
    jeff

    Ummmm. Isn't it TV4 and (ch20 OR ch21) and any two RC channels 23 apart?
    
    23 times 20khz spacing = 460khz beat frequency

If I remember right, our club Pikes Peak RC, voted earlier this
year to go right over to the full channel system when it comes
legal.  That is, we do not plan to make any provisions for the
people flying the old wideband equipment.

Of course, its fair to point out that we have neither TV4 (Denver
has it, but then Denver has the Broncos too...), nor a heavy
Pager problem, though the pagers we do have are well positioned
on top of Cheyenne Mountain.

Personally, I feel that your system of allowing the wideband
folks to tie up adjacent channels, while workable, unfairly
penalizes those folks that have bit the bullet and gone
narrowband, while at the same time rewarding those who haven't. 
While I feel that the policy of "let them (widebanders) fly and
get shot down, attrition will take care of it all" is callous,
under the circumstances of your frequency control system, its
just deserts for them.

I'll tell you, the new equipment is *so good* that its really
foolish to use the old stuff, assuming one can afford to buy it.

    Our club isn't planning on doing anything different for freq. control
    come '91. Fly what you bring, take the consequences if you push
    your luck. We still have guys flying on 27 mhz, in contests no less.
    
    At distances from our field ranging from 200 yards to 10 miles we
    have the following: police sub-station xmtr., TV channel 4 xmtr.,
    medical office complex, technical-vocational school electronics
    lab, A.F. Weapons Lab, Sandia Labs, ATC route control center,
    innumerable bozos in jacked-up 4X4s, all with C.B.s driving by
    on 3 sides of the field, golfers at the far end of the field with
    pagers, walkie-talkies and lord knows what else, R/C car guys at
    the other end, all on 75 mhz, we hope, and I'm sure I've forgotten
    something.  
    
    If we can survive all that, and we do, then we can't get too excited
    about what '91 will bring.
                                                                        
    Terry
    

    
    
    Terry,
    	Can you, or anyone else touting the "Attrition will take care of
    the OWB equipment in short order" philosophy, guarantee that as these
    planes get shot down they won't land on a person? Persnally I don't
    think this is setting a very good example for the newcomers.
    
    Dan Snow
    TAY-2 
    DTN 227-3202

    Yesterday, I got my CRRC newsletter in the mail.  It contained
    templates for the "required" freq. pins for the new freq. control
    system.  The problem is that the pin templates are WRONG for
    channels 11-14 and 34-37.  (Should ban TWO other channels for
    simultaneous operation not just one...)

    So get things straight in my mind and (hopefully)  avoid some of the
    confustion for other in the future, I wrote a quick and dirty
    program to generate all 2IM combinations.  Here is the output from
    my program:

    Channel combinations to avoid for GOLD STICKERED transmitters

    11 :  34  57            34 :  11  57            57 :  11  34
    12 :  35  58            35 :  12  58            58 :  12  35
    13 :  36  59            36 :  13  59            59 :  13  36
    14 :  37  60            37 :  14  60            60 :  14  37
    15 :  38                38 :  15
    16 :  39                39 :  16
    17 :  40                40 :  17
    18 :  41                41 :  18
    19 :  42                42 :  19
    20 :  43                43 :  20
    21 :  44                44 :  21
    22 :  45                45 :  22
    23 :  46                46 :  23
    24 :  47                47 :  24
    25 :  48                48 :  25
    26 :  49                49 :  26
    27 :  50                50 :  27
    28 :  51                51 :  28
    29 :  52                52 :  29
    30 :  53                53 :  30
    31 :  54                54 :  31
    32 :  55                55 :  32
    33 :  56                56 :  33


    Channel combinations to avoid for SILVER STICKERED transmitters

    11 :  12  34  57        34 :  11  33  35  57    57 :  11  34  56  58
    12 :  11  13  35  58    35 :  12  34  36  58    58 :  12  35  57  59
    13 :  12  14  36  59    36 :  13  35  37  59    59 :  13  36  58  60
    14 :  13  15  37  60    37 :  14  36  38  60    60 :  14  37  59
    15 :  14  16  38        38 :  15  37  39
    16 :  15  17  39        39 :  16  38  40
    17 :  16  18  40        40 :  17  39  41
    18 :  17  19  41        41 :  18  40  42
    19 :  18  20  42        42 :  19  41  43
    20 :  19  21  43        43 :  20  42  44
    21 :  20  22  44        44 :  21  43  45
    22 :  21  23  45        45 :  22  44  46
    23 :  22  24  46        46 :  23  45  47
    24 :  23  25  47        47 :  24  46  48
    25 :  24  26  48        48 :  25  47  49
    26 :  25  27  49        49 :  26  48  50
    27 :  26  28  50        50 :  27  49  51
    28 :  27  29  51        51 :  28  50  52
    29 :  28  30  52        52 :  29  51  53
    30 :  29  31  53        53 :  30  52  54
    31 :  30  32  54        54 :  31  53  55
    32 :  31  33  55        55 :  32  54  56
    33 :  32  34  56        56 :  33  55  57

    Hey Dan,
    
      How about updating the postscript pin note in 953.3 with the
    combination numbers in a smaller font like Dan did with the CMRCM ones?