On Tue, 29 Jul 2003 23:04:00 +0100, Paul Burridge
wrote:

On Tue, 29 Jul 2003 04:12:43 GMT, (John Crighton)
wrote:

Or find, beg, borrow, "buy used," or build an ordinary
AM R/C transmitter. Ten quid should get you an old
style metal cased Futaba transmitter.

Hi John,

I've already got an AM tx and rx set-up, but am loathed to use it due
to the much increased risk of interference from the speed controllers,
motors, etc., which as you will know, is far more likely with an AM
system. Keep thinking!
--

Hello Paul,
I would try out your old AM set for sure. You never know
your luck. If the servo connections are compatible it will
only take a short time. What brand/model?

I agree with you that the AM set has an increased risk
of interference from your own motors but you said some
time ago that your robot works fine at your place but at
the venue with other competitors and their transmitters
around, the interference is bad for you with your present
Sanwa FM set.

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.

Regards,
John Crighton.
Sydney

On Wed, 30 Jul 2003 01:11:15 GMT, (John Crighton)
wrote:

Hello Paul,
I would try out your old AM set for sure. You never know
your luck. If the servo connections are compatible it will
only take a short time. What brand/model?

It's a Futaba and it *has* been tried. We used it last time out solely
for weapon actuation and the result was *outrageously* dangerous and
uncontrolable. Far, far worse than FM. You wouldn't have believed it
if you hadn't seen it for yourself. It was pure luck that no one was
killed or seriously injured.

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!
--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill

On Wed, 30 Jul 2003 01:11:15 GMT, (John Crighton)
wrote:

Hello Paul,
I would try out your old AM set for sure. You never know
your luck. If the servo connections are compatible it will
only take a short time. What brand/model?

It's a Futaba and it *has* been tried. We used it last time out solely
for weapon actuation and the result was *outrageously* dangerous and
uncontrolable. Far, far worse than FM. You wouldn't have believed it
if you hadn't seen it for yourself. It was pure luck that no one was
killed or seriously injured.

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!
--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill

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

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

In article ,
says...

Hi chaps,

I've decided to bite the bullet and try to build an RF filter for
40Mhz. This filter will ideally have a very, very sharp characteristic
at one single spot frequency +-20Khz and attenuate the crap out of
anything either side of this. It'll need to be tunable over a range of
say 200Khz. Can anyone give me a steer on what type of arrangement
would be best suited to fit this purpose?
Thanks,

p.
--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill


i just read this thread and had a few thoughts. i don't know what kind
of interference you're dealing with, nor do i know what restrictions are
placed on your competitions.

i was thinking about front end overload, also. the types of interference
vary in different countries, but those paging towers and, taxis, etc.
all play hell on a front end. you really need a spectrum analyser to
figure out what you're deaaling with.

as for those ceramic resonators, they're ok, but in the better
receivers, they're followed by if xfmrs to get rid of the spurious
response of the ceramic filter.

since you are thinking of just starting from scratch, here's what i'd do
if you're not bound by rules.

http://www.aerocomm.com
http://www.radiometrix.com

cost? i dunno. i figure if you can afford one, good. then you can spend
more time on the robotics and weaponry.

if you can use these, the question becomes a matter of whether you can
retrofit one of these in time. i'm not ready to look into using them yet
and therefore haven't gotten into the details. so i don't know what
you'd have to do to get a PWM signal in and out, but since they handle a
higher data rate (1 Mbps) than std R/C PWM, you could bust the PWM
signal up into little "chips" and reconstruct it on the receiving end.
maybe an integrator/LPF would be all you need. on the other hand, maybe
you can just send" the PWM directly. I'm sure the applications engineers
could help.

hope this helps.

mike

In article ,
says...

Hi chaps,

I've decided to bite the bullet and try to build an RF filter for
40Mhz. This filter will ideally have a very, very sharp characteristic
at one single spot frequency +-20Khz and attenuate the crap out of
anything either side of this. It'll need to be tunable over a range of
say 200Khz. Can anyone give me a steer on what type of arrangement
would be best suited to fit this purpose?
Thanks,

p.
--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill


i just read this thread and had a few thoughts. i don't know what kind
of interference you're dealing with, nor do i know what restrictions are
placed on your competitions.

i was thinking about front end overload, also. the types of interference
vary in different countries, but those paging towers and, taxis, etc.
all play hell on a front end. you really need a spectrum analyser to
figure out what you're deaaling with.

as for those ceramic resonators, they're ok, but in the better
receivers, they're followed by if xfmrs to get rid of the spurious
response of the ceramic filter.

since you are thinking of just starting from scratch, here's what i'd do
if you're not bound by rules.

http://www.aerocomm.com
http://www.radiometrix.com

cost? i dunno. i figure if you can afford one, good. then you can spend
more time on the robotics and weaponry.

if you can use these, the question becomes a matter of whether you can
retrofit one of these in time. i'm not ready to look into using them yet
and therefore haven't gotten into the details. so i don't know what
you'd have to do to get a PWM signal in and out, but since they handle a
higher data rate (1 Mbps) than std R/C PWM, you could bust the PWM
signal up into little "chips" and reconstruct it on the receiving end.
maybe an integrator/LPF would be all you need. on the other hand, maybe
you can just send" the PWM directly. I'm sure the applications engineers
could help.

hope this helps.

mike

sorry, i did mean PPM, not PWM

a link was provided earlier. might be this, or it may link to this.

there're links to radios for robot wars. according to this page there
are 2 bands allowed, so maybe those 2.4GHz radios are verbotten. that
sucks! it's a robot competition, not a ham competition.

http://homepages.which.net/~paul.hills/Radio/Radio.html

mike

sorry, i did mean PPM, not PWM

a link was provided earlier. might be this, or it may link to this.

there're links to radios for robot wars. according to this page there
are 2 bands allowed, so maybe those 2.4GHz radios are verbotten. that
sucks! it's a robot competition, not a ham competition.

http://homepages.which.net/~paul.hills/Radio/Radio.html

mike

On Thu, 31 Jul 2003 06:48:57 GMT, (John Crighton)
wrote:

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?

Thanks again for your input, John.
I only have these two r/c model transmitters to test against
themselves. It would be a remarkable coincidence if *both* were
defective to the same degree. I can, however, confirm that they both
put out almost exactly the same power as each other. I infer from that
that there is no problem with either.

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?

Yes.

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?

Yes.

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?

Ah, well I haven't tried that one. Good suggestion. I'll do so as soon
as I have a colleague handy to assist!

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?

No one's permitted to carry out such tests at the venue. As soon as
each competitor arrives, all transmitters are immediately impounded
and only released on a book-out/book-in basis under supervision of one
of the organisers' technical bods and only then if no one else is
using that frequency elsewhere in the building at the time.

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

It's a very common problem indeed, yes.

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?

It's a pity I sold my last spectrum analyser about the same time as I
started this lark! Big mistake, that. :-( However, I'm given to
understand the studio people have one and keep an eye open for any
such 'irregularities'.

[other valid points noted and snipped]

Things are looking very much better this time than last. I've
discovered a good many possible causes of the problems we had last
time out and have remedied all those I've found. I've also carried out
improvements suggested here by your good self and others. I'm leaving
nothing to chance this time!

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

So will I.
--

"I believe history will be kind to me, since I intend
to write it." - Winston Churchill