Long Range UHF RC system now avail on STOCK - Page 4 - RC Groups
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Aug 10, 2008, 02:45 PM
I'd rather be flying...
djdaveq's Avatar
whats the range with and without this 7 booster ? will this work with futaba radio 9chp?
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Aug 10, 2008, 02:58 PM
albertocvr's Avatar
Thomas :
Any chance to see rssi info in Db via your ifosd ? .
Itīs spead spectrum and frecuency hopping ( like futabas fasst 2,4 ), so does not lock in a frequency like spektrums 2,4 , right?
Aug 10, 2008, 03:16 PM
Registered User
thomasscherrer's Avatar
alberto, read the thread, RSSI is allready explained.

djdaveg, range is also explained on page 2-3
range is hard to promisse anything about, but the 500mW version
with little (bad whip) should give you at least 2-4km range even in city with tons of noise on the band.
the 7w booster will give you at least 6-12km,
better TX antenna can easily double those figures again,
if no noise and if perfect line of sight, 50-100km range should be possible in therory
and that is even with 500mW ! but I normally dont thrust PC simulation when it comes to range, real field experiance is much better, and the results will be much different from site to site exactly as we see with all other radio equipment and the achived range.

my first version was with only 100mW and using a receiver with only -100dBm sensitivity, I flew that one 2-4 km away several times,
this new system have 10db better receiver, and diversity !
and 7 dB more transmitter power as standard, so with a link budget with over 20 dB gained the range should be 6 times as good, that is 12-24km (with 500mW)
why I say such a wide range 12-24 ?? that is due to all the things that normally interfer with the optimal: like how is the installation in plane ?
both antennas angle to the TX, noise from plane, noise from other transmitters,
things in the way ? atmospheric interferences ? transmitter antenna used ?
Aug 10, 2008, 03:32 PM
fmkit's Avatar
thomas, transmitting video in 70cm band is legal in US. Imagine range using your 7w booster - this would be practical design.
I'm using UHF for control and learned in the past year that 200mw is all that one needs to fly further than horizon. Only need for more power if controlling RC truck or from inside a building or from underground
also I want to note that $10 FRS radio such as Motorola FV300 few times more sensitive.
Aug 10, 2008, 03:58 PM
Registered User
thomasscherrer's Avatar
yes it is also legal here for radio amateurs, but with a more narrow bw,
the 7W booster is for sale as a stand alone unit,
remowing the case and connectors and fan might even get you info flight weight :-) so go for it. removing the input attenuator will give usefull output from 20-50mW input, nice.

yes I simply suggest more power to give people better margin to noise
and to be sure they are happy with the range.

yes I also have radios like the FV300 here
we normally pay about double that price, but then we get rechargeable batteries in both units and also a nice docking station with charger !
have you measured their BW and Sensitivity ?
you know you cant compare radioes sensitivity as long as they use different modulation bandwitdh.

it's like our wideband video receivers have like -85dBm if they are the good types,
that sounds like pure crap compared to narrow band FM radioes.
but it is actually not, if you look at the signal bw of 6-10MHz

take a prof SSB or CW receiver they can hear -130dBm in a much smaller bw
Aug 10, 2008, 04:27 PM
fmkit's Avatar
I'm just saying nothing beats UHF in range,
200mW is already overkill for aircraft control

here is FV300 installed on Kyosho mini inferno,
even w/ 1" antenna range limited only by video link

not as pretty as your system but receiver sensivity is incredible .. as expected from dual conversion RX with SAW and crystal filters.
Aug 11, 2008, 01:33 AM
I'd rather be flying...
djdaveq's Avatar
amazing dude
Aug 11, 2008, 09:04 AM
Registered User
thomasscherrer's Avatar
about 2.4GHz video tx and this UHF RC receiver:
I just got a mail from a customer, he took off the RC TX antenna
and noted the RC range, then tried to jamm his UHF RC receiver with his 500mW 2.4GHz video TX, not at all possible ! even when the two antennas directly on top of each other he said no change in range at all, so the filters must perform as expected :-)
Aug 13, 2008, 05:48 AM
Registered User
thomasscherrer's Avatar
latest news to all customers that are waiting paitient:
the last parts (radio modules) are now confirmed to be delivered 19th of August,
I am preparing as much as possible of all the other things to save time.

new customers are welcome to contact me, I have prepared a few more units to help out new customers also.
Aug 13, 2008, 06:12 AM
Registered User

I do not have time to sent Fuataba trainer Cable to you yet.
Do not ship my 7w.
Wait for the cable to arrive, after you success to modify it then you can sent it together with my 7w, is that OK?
Aug 13, 2008, 06:27 AM
Registered User
thomasscherrer's Avatar
yes that is perfect, I have yesterday made a new version of the 7W booster,
and slightly improved the low pass filter, more will come on this page asap:

I had arranged a meeting this weekend with a few Futaba owners of my local club,
i have to delay that now I see, but ok, will look forward to see your cable and make real life tests with different Futaba, I also see some other Futaba units uses the round DIN style connector, that is easy and cheap to get arround here.
Aug 14, 2008, 01:34 PM
Registered User
thomasscherrer's Avatar
more results from customers:
my UHF RC system is fully compatible with Futaba T7CAP/FF7 he said,
the protection diode inside the transmitter gets darn hot, so simply short it
will also give you a bit higher voltage and less power loss.
I also got warned about the Futaba square 6 pin connector !
it is full of loose connections unless it is pressed in to the max !
Aug 14, 2008, 01:56 PM
FPV Flyer
wavess's Avatar
Originally Posted by thomasscherrer
I also got warned about the Futaba square 6 pin connector !
it is full of loose connections unless it is pressed in to the max !
Iīve never had an issue with futaba square connector. BTW conectors are made for fit in each other always to the max
Aug 14, 2008, 02:18 PM
Registered User
thomasscherrer's Avatar
I dont have experiance my self with Futaba and specially not with this connector,
I just translated and forwarded to you what my customer said:
he is not specially happy about this connector, and had some bad connections
when he is not extra carefullt to press it in all he can,
I use another brand (Multiplex) and I am super happy about that connector they use,
I feel I can thrust my 2000$ FPV plane on this connector, and that is how it is ment to work for me.

I hope it will be perfect all the way for you, just be sure it is pressed in,
and dont pull the wire so it gets loose. I think that is what me ment the warning was about.

and also: maybe some cheap un-original copy trainer plugs
maybe not fit perfectly ? and gets loose if not carefull ?
is that a chance ?
Aug 14, 2008, 02:52 PM
Registered User
tychoc's Avatar

I notice that in your starter pack you included two receivers. Would you consider selling a package containing only one RX? If so, what would the price be?



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