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UHF RC system version 3 booster 7W V3.33 Latest New Version

Booster V3.10 Old version
see also 30W PA stage for ultra long range
see also old version 2, we have test flown V2 for over 1yrs now
see also version 3 rc system

Here is the NEW PA Booster version 3.33 with improved and bigger heatsink
See size compare from old to new heatsink pic 1 pic 2

This tiny PA booster is designed to get 500mW input from the V3 RC system
Boosting 0.5W to 7W will increase the range by at least a factor 3 !
The PA module consume about 2A at 7.2V and give 7 to 8 Watt out of pure long distance RF power
I use a big heatsink so it can be opperated 24hr if needed.
The PA booster box is a small metal case 58mm wide, 72 mm long,27 mm height

The output filter response performance is mesured on network-analyzer,
0.3dB insertion loss, and about 30dB attenuation allrady on the first harmonic

Inside the booster version 3.33 note the end plate connector PCB's

this extra PCB makes it faster to assemble, and lower loss.
The new booster have a little bit better specifications.

Booster Specifications:
Vin, Current in, RF Power Out, Efficiency:
8V   2.3A        9.1W          45.5%
7V   2.0A        7.6W          51.7%
6V   1.8A        5.2W          48.2%
5V   1.6A        3.1W          38.7%
4V   1.2A        1.5W          31.2%
3V   0.7A        0.7W          33.3%
2V   0.2A        34 mili Watt  NA
1V   0.0A        6 micro Watt  NA
So it is possible to change RF power by simply using powersupply voltage adjust.
a 6 cell NIMH battery and a rotary switch (brake before make) can be used.

RF cable
The BNC - BNC cable you need to use from standard 500mW tx unit to your booster (is not supplied)
use any 50 ohm impedance cable with loss from 0dB to 6dB at 500MHz.
network cables with BNC 10base-2 are 50 ohm, cheap and available world wide.
Different cable types have different loss, here is the max length allowed using different cables:
RG-58CU 18meters (59ft)
RG-223 17meters (55ft)
RG213U 37meters (121ft)
Ecoflex10 67meters (219ft)

install and use
It is recommended to place this booster with antenna as far away from ground station video receivers
as needed, to achive full video range ! this must be checked with booster on/off.
mount booster with antenna as hight and free as possible to achive as good range as possible.
Directional antennas will give you futher range, a gain of 10dB = 3 x the range !
ham radio beam antennas for the 70cm band are cheap and easy to get worldwide.

old 3xx rx firmware:
The ultra sensitive receiver will be blocked/jammed if distance to booster antenna is under 10-20meters so avoid that !
no permanent harm to the receiver, only RC lock up -> failsafe, but can be harmfull to plane !
With no booster (500mW standard) avoid distance to receiver under 2-3 meters !

NEW 307-308 or higher RX firmware:
No more blocking problems, an RX can be as close as 25cm (10 inch) from a booster at 7W before minor blocking is detected.

Temperature Check your booster is not running too hot, a heatsink temperature of 50C (122F) is maximum allowed !
50C is arround that temperature it is impossible to touch the heatsink for 3sec !

Power supply MAX is 8.4V, max supply current 2.5A, newer ever exceed that.
Use 6 cell NIMH battery or 2 series LIPO cell.
Do NOT reverse voltage polarity, a fuse inside the Booster wil blow if reversed and if lucky the amplifier is possible to repair cheap
Do NOT opperate this PA without output antenna connected.

High / low power
see on the supply voltage chart you can use supply voltage to adjust the watt out,
and then also the range, the idea is to use as little as possible power, seek far away, looking for range problems,
when you get problems you can switch up the power and continue your mission or return home safely.

here the normal 8V supply from 2S lipo, and via the switch 3.6V will give you 1W

This is a more safe way to do it, you can change lo / hi on the switch.
And, when lipo is empty the nimh pack will save your plane.
you can use other cell counts to fit your needs, for the low power section, maybe use 4 or even 5 NIMH cells
sorry about the ugly pictures, they where made in 15 sec :-)

-Thomas Scherrer OZ2CPU (active with this from 2006-2009) this page was last updated November 17, 2009