On Wed, 30 Jul 2003 21:28:29 +0100, Paul Burridge
wrote:

Even if you do not fit the AM set to the robot, take the
working AM set in a box to the venue and see if the
servos misbehave in that electrical noisy environment.

See above. We won't be using that set-up ever again for this
application!
--

Hello Paul,
I think you are missing my point when you said,
"We won't be using that set-up ever again for this application!"

My point is this. If the radio control set works OK, while just
sitting in its own cardboard box , at the noisy Venue, meaning,
the servos work nice and smooth. If you then install that same
Rx and servo set into your metal box robot and the servos
play up, that is now an " installation problem."
You cannot blame the gear.


Let's try and sort this out with some basic checks.

Using a field strength meter (which is just a simple
crystal set with a large moving coil meter as discussed
months ago, I assume you have made one already), are
both the Sanwa and Futaba transmitters producing
similar output power when compared to a known
good working transmitter? Yes or No?

At your place, are range checks of both the Sanwa
and Futaba R/C sets, on there own, not installed
in anything, over 100 yards . Yes or No?

At your place, are range checks of both the Sanwa and
Futaba R/C sets installed in the robot or metal test box
with "no" drive motors connected still over 100 yards.
Yes or No?

At your place, are range checks of both Sanwa and
Futaba with drive motors being controlled and
running nicely, still over 100 yards. Yes or No?

At the noisy Venue, while doing a range check of less than
30 yards with all other competitors absent or their
transmitters switched off in the Tx compound, do both
your Sanwa and Futaba R/C sets play up?
Yes or no?

At The Venue, do other competitor's radio control
sets play up like yours Yes or No?

At the Venue have you scanned the band with a
simple crystal set type radio or fancy scanner for some
******* with a transmitter who is determined to give
you, personally, a hard time?

One last thought, I take it that you have sorted your
aerial out so that you do not have a long dangly
piece of wire as an antenna lead-in, inside the
metal robot body from the base of your whip antenna
mounting bracket to the Rx input.
If you do have a long wire lead-in, that is bad as it
will pick up local motor noise very nicely.
If your Rx is a long way away from your antenna base,
use coax for the lead-in as explained here.
http://homepages.which.net/~paul.hills/Radio/Radio.html

If after all that basic stuff has been checked and still no joy
then consider a dual conversion superhet Rx. like this one.
http://www.norcim.fsnet.co.uk/Index.htm#U
You could scratch build from the given circuit and the
description of how it works on that web site.
Or buy the kit from Micron for 32 quid.

If you are still having problems after all that,
sorry Paul, I give up.

Regards,
John Crighton
Sydney