I'm a very long time PICAXE Forum member,although these days rarely contribute due to other activities.
PICAXE based wireless data however still grabs my attention - as in your case. Herewith some thoughts that both I (& probably others !) would appreciate your responses to-
* Guess you mean -ah- 25 mW (milliWatts) transmitter POWER rather than 25 mA (milliAmps) CURRENT ? Irrespective such flea power is hardly going to cook your finals with poor SWR (Standing Wave Ratio)!
* EXACTLY what are your control/data needs ?
* EXACTLY what 433 MHz modules are you using (some now are pretty hopeless) ?
* Local UHF RF and physical environment ?
* Does your setup have scope for diverse antenna ?
* Most PICAXE 433 MHz ASK data links are good for only a few 100 m, so do you wish more reliable comms OR better range ??
* Do you realise 433 MHz ISM regulations usually allow only
receiver gain antenna ?
* Are you after omnidirectional coverage or directional point to point?
*
As 433 MHz setups usually involve control of both the Transmitter (Tx) & nearby receiver (Rx) you can hence probably readily monitor antenna tweaks at the RECEIVER end. Is this your case?
* Does your
RX module offer RSSI (Received Strength Signal) info to allow monitoring ? Otherwise -
* Do you have available a 433 MHz scanner of general coverage UHF receiver that'd show signal strength ?
* Do you have a helper who can inform of antenna tweak effects by arm waving, shouting, cell phone or 2 way radio etc?
FWIW - If 433 MHz data
transceiver modules (such as the esteemed HC-12) are used, suitable code perhaps could maybe even inform you back at the Tx end of antenna change benefits.
Stan. in New Zealand (Radio ham ZL2APS - since 1967)