The internet is world-wide.
I’m in the USA and it doesn’t work for me, either. I tried looking at their Manuals page, and looking in their catalog but perhaps it’s too new or it’s discontinued?
Google found the manual on someone else’s website:
TechEdu.com
Those ICs used appear to be pin for pin compatible with the TX2 and RX2 chips.
Ohms law won’t help you figure out the output power. The circuit must be designed to be no more than the maximum allowed for this type of unlicensed transmitter. The easiest way to boost range is to increase voltage to the transmitter’s output transistor (while keeping it the same at the IC) but then you are likely to be over the legal power limit.
Another easy way is, if it is a 27MHz as this one is, put a CB Radio antenna on the transmitter. And check receiver antenna length It isn’t as critical but should be as long as you can make it up to 9 feet. ;’)
You may also find your range is being shortened by interference. The receiver is using a simple design that is very sensitive with few parts, but is by nature wideband and very much subject to interference. That’s why you can’t run two cars on 27MHz even if they are on different frequencies. So you could replace the front end with a superheterodyne receiver. It’ll take more parts.
Maybe a tuned front end, with mixer followed by 455KHz ceramic filter IF and an MK484 as a 455KHz IF amp/detector. Yes, I’ve thought about this and have some of those ICs already. You must get a crystal for the receiver then, one that is 455KHz off from the transmitter crystal.
Hmmm…. just did a search, here’s a circuit tailor made! Leave off the LM386, use the output from the ZN415 pin 7, run into Pin 14 of your receiver IC AF2311.
Superheterodyne Receiver
Now- why do you need more range? You are likely to be interfering with other RC cars if you are racing others, and how far do you think you’ll be from your car?
