Changing Frequencies.....danger??

[Bob Richards]

I've changed frequencies up to 8 channels away with no
problem. I've always had them checked with a spectrum
analyzer afterwards to make sure it still was in spec.

Several parameters must be checked, however. The
center frequency must be checked, obviously. The
sidebands must drop off below a certain level to meet
the 1991 narrowband spec (gold sticker criteria at
that time). The spurious emissions must by down be a
certain amount, and the harmonics (multiples of the
center frequency) must meet certain criteria.

The FCC, IMHO, is not really concerned if we interfere
with one another, they are more concerned that we do
not interfere with commercial broadcast and emergency
services. Their mandate is to protect commercial
broadcast services. We are secondary users, and if a
72mhz paging system causes our planes to drop out of
the air, as long as the 72mhz pager meets their specs
then we have no recourse. God forbid we interfere with
the pager system! (Thank goodness the technology has
made 72mhz pagers rare these days).

I find it a little amusing that, technically, we (the
general public) should not be changing transmitter
crystals. However, anyone can order/purchase them.
Hmmm. I'm sure it is Futaba's official position that
we not change crystals (wink, wink).

JMHO :-)

BTW, I understand the RC car meets have competitors
swapping crystals all the time.

Bob R.
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