1. Yes.  A 100uf cap on the power supply rails helped it work better. =20
Not sure if more will help.

2. Logic analyzer on the serial lines showed nothing during dev.  My=20
scope won't measure the 433 Mhz side.

3. 69.2-cm wavelength means one sixth =3D ~11.5 cm.  The IPEX-to-SMA=20
interfaces I have are 15cm.  If going to 10cm cables would help, I can=20
definitely order some.  I *can* do away with the connectors, but would=20
prefer to do that as a last step before making any permanent cuts etc.

4.  Hmmm... good thought, but need to find one that will measure RF.

5 and 6.  Greek.  I'll research what these antennas are.

These are the modules...
https://www.amazon.com/Wireless-Transceiver-Module-433MHz-antenna/dp/B010ON=
WKE6

These are the interface cables...
https://www.amazon.com/gp/product/B00UTT8842/ref=3Doh_aui_detailpage_o05_s0=
0?ie=3DUTF8&psc=3D1

These are the antennas...
http://microcontrollershop.com/product_info.php?products_id=3D7268

Cheers,
-Neil.



On 8/4/2016 1:26 AM, James Cameron wrote:
> G'day Neil,
>
> I'm also experimenting with 433 MHz modules at the moment; not serial
> modules, but radio modules.
>
> Techniques to suggest;
>
> 1.  make sure the receiver module power supply is clean and well
> filtered,
>
> 2.  capture the receiver data waveform and compare it to the
> transmitter data waveform, in case you have some source of noise,
>
> 3.  mount the transmitter module to the base of the antenna and keep
> the transmission line under one sixth of the wavelength, and if
> possible do away with connectors,
>
> 4.  use a frequency counter or other instrument to verify the
> transmitter frequency; at least to get some more significant digits,
>
> 5.  try a slim jim or j-pole antenna [A] at 433 MHz using television
> ribbon cable (balanced feeder), then tune it, (for me, this can give
> about 500 metres range in the open),
>
> 6.  try a yagi [B].
>
> I've also had some problems with 151 MHz modules that turned out to be
> my misread of datasheet; data input needed a series resistor to ensure
> FM deviation was in spec.
>
> I've also had spurious transmitters nearby at 433 MHz.  In one case a
> weather station outside transmitter that was continually transmitting,
> bringing range of other devices down to a metre or so.  A Spectrum
> Analyser can help with this.
>
> Got references for those modules?
>
> References:
>
> A.  calculator for lengths and cut points,
>      https://m0ukd.com/calculators/slim-jim-and-j-pole-calculator/
>
> B.  calculator for three element yagi,
>      http://www.csgnetwork.com/antennae3ycalc.html
>

--=20
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