For best efficiency and amplifier performance: use a resistor as the RF load.
Kevin - if you try to keep things legal you will get a lot better help here. There are folks here who know how to get 200-500 feet range without breaking the law. If this device has a commercial purpose, apply for an experimenter's permit. I's nearly free, and lasts 2 years
- form 442 with the FCC ... assuming you are in the USA.
Frank Raffaeli
Hi all, I have a VCO set to 106Mhz with the VCO feeding into a CC buffer amplifier. The buffer amp then feeds into a CE amplifier the active device here being the BFG97. This then feeds into a class C amplifier again the active device being a BFG97. On the CRO I'm seeing a Vout of 21volts RF the Vcc being 12v.
The antenna is a 50ohm telescopic whip. The thing is I'm not getting much range with this setup maybe 30 meters.
I know the antenna isn't great. I have to get around to designing a hi gain antenna in the comming weeks. The Ptot of the BFG97 is 1 watt so do i chain a couple of class c amps to get a hi power output?
How do I get a good efficiency from the amplifier stages?
Any thoughs welcome. Kevin.
It looks like he's in Ireland.
Graham
And that was even before I noticed his surname - lmao ! A sure give away.
Graham
And where are you from Pooh Bear?
There's this book written by A.A.Milne.....
Graham
Did M. Milne also write the one called, "The Tao of Pooh"?
I found that one to be pretty cool. %-}
Cheers! Rich
with 21V RF you should be doing km not meters; something is oscillating on totally different frequency, or output stage is overdriven.
IMHO on 106MHz to reach 30 meters is enough just a VCO & the following amplifieing stage ...
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