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Nov 22, 2013, 01:29 PM
RC beginner
yes, as mentioned in post #69. im going to put up more details on my 2.4ghz version so we can see exactly whats involved.
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Apr 02, 2014, 10:56 PM
Did you ever get around to taking some photos of the 2.4ghz version? Looks like this could be good to get a bit more range out of the diyFlysky rx.
Apr 04, 2014, 09:47 AM
RC beginner
i will try to get some pics and more info on the 2.4ghz version but remember rx need LNA to increase range not power amp. preamp and antenna upgrade are not only more effective but cheaper and actually legal. ive made considerable progress in that area recently so really need to get a thread going for it. problem is my other project threads here just refuse to die off like they are supposed to. BAD project threads... no tv for you tonight!
Apr 04, 2014, 11:29 AM
Stuart
srnet's Avatar
Quote:
Originally Posted by dave1993
i will try to get some pics and more info on the 2.4ghz version but remember rx need LNA to increase range not power amp. preamp and antenna upgrade are not only more effective but cheaper and actually legal. ive made considerable progress in that area recently so really need to get a thread going for it. problem is my other project threads here just refuse to die off like they are supposed to. BAD project threads... no tv for you tonight!
A good LNA can make a big difference to reception of telemetry from RFM22B type transmitters.

Using a standard RFM22B as the receiver with an LNA and just an Omni directional antenna (QF Helix - minimal gain), I have been able to receive telemetry packets from $50SAT (100mW only TX) at between 600-900km, which ain't half bad.
Apr 04, 2014, 12:24 PM
Very cool. I understand that antennas and LNA's are a better route, but I just like building and playing with stuff. Not for anything serious.

Please do make another thread on those subjects and also post a bit of info here! It would be greatly appreciated!
Jun 27, 2017, 08:03 PM
Registered User
Can this rf2126 be use in a 2.4ghz vtx?
Also if use in rfm22b will it be comparable to rfm23bp?
How much should be the input power,any limit?can not find any details for the input power.

Thanks
Jul 17, 2017, 12:48 AM
Registered User
vollrathd's Avatar
Question
Is this legal in the USA for our RC transmitters? For me, I'd prefer that no one in my club uses one of these while I'm flying any of my models.
Jul 18, 2017, 01:46 AM
Stuart
srnet's Avatar
Quote:
Originally Posted by vollrathd
Question
Is this legal in the USA for our RC transmitters? For me, I'd prefer that no one in my club uses one of these while I'm flying any of my models.
Even ignoring legalities, the is the obvious issue that the amplifiier is quite capable of producing significant harmonic interferance, in particular when overdriven.

Of course this type of device is normally built and tested by people who understand such things and have the equipment to check that the amplifier is not causing interfernce to other users of the RF spectrum such as aircraft navigation systems the emergency services etc.
Jul 18, 2017, 01:20 PM
Registered User
vollrathd's Avatar
Quote:
Originally Posted by srnet
Even ignoring legalities, the is the obvious issue that the amplifiier is quite capable of producing significant harmonic interferance, in particular when overdriven.

Of course this type of device is normally built and tested by people who understand such things and have the equipment to check that the amplifier is not causing interfernce to other users of the RF spectrum such as aircraft navigation systems the emergency services etc.
This sort of illegal amplifier thing also hit the CB radios of some years back.
Sep 16, 2018, 09:37 AM
Registered User
anyone able to make it work for 433mhz?
currently searching for 433mhz booster amplifier.
thanks
Sep 16, 2018, 02:10 PM
Registered User
That's amplifier

https://www.minikits.com.au/electron...m-7W-Amplifier
Sep 16, 2018, 06:06 PM
Registered User
vollrathd's Avatar
Quote:
Originally Posted by axljackass
anyone able to make it work for 433mhz?
currently searching for 433mhz booster amplifier.
thanks
From what I've read, you should have a ham radio license for this sort of thing. And equipment to make certain your setup isn't splattering harmonics all over the radio band.
Sep 17, 2018, 04:40 AM
Registered User
hi renatoa,

thanks but 7w is too much dont want to have brain cancer.LOL

looking for at least 2watt PA LNA that i can attach to my Si4432 433mhz.

Im thinking of this Power Mosfet RFM07U7X from RFM23BP but need someone to RF design it also this BLT53A is a good candidate.

If we have RF Engineers to help us it would be great or someone knows how to RF design.
Sep 17, 2018, 07:46 AM
Stuart
srnet's Avatar
Quote:
Originally Posted by axljackass
hi renatoa,

looking for at least 2watt PA LNA that i can attach to my Si4432 433mhz.

If we have RF Engineers to help us it would be great or someone knows how to RF design.
Its not as simple as you might think.

Amplifying the output of the Si4432 is easy enough, the clever bit is building it with filters that are good enough to limit the inevitable harmonics.

And as mentioned each user would need the equipment to measure the harmonics to ensure your setup is not causing widespread disruption to users in other parts of the RF spectrum.

Using such an amplifier for RC would be illegal in a lot of places, including the US, so understandable perhaps that there is not a lot of interest.
Sep 17, 2018, 08:52 AM
Registered User
vollrathd's Avatar
Quote:
Originally Posted by srnet
Its not as simple as you might think.

Amplifying the output of the Si4432 is easy enough, the clever bit is building it with filters that are good enough to limit the inevitable harmonics.

And as mentioned each user would need the equipment to measure the harmonics to ensure your setup is not causing widespread disruption to users in other parts of the RF spectrum.

Using such an amplifier for RC would be illegal in a lot of places, including the US, so understandable perhaps that there is not a lot of interest.
As a minimum, what ever design you come up with needs to be checked out with a quality spectrum analyzer. Those things are not cheap, with prices starting at around $3000.

430 mHz RF designs are far more complex than audio frequencies. It would be very easy to design a 433 mHz amplifier that transmits on every frequency except 433 mHz!
Last edited by vollrathd; Sep 19, 2018 at 01:05 AM. Reason: 433 MegaHertz, not KiloHertz


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